Energy Foundations

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ENERGY FOUNDATIONSfor High School Chemistry

A projec o he American Chemical Sociey Educaion Divisionmade possible by generous unding om BP


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2 Energy Foundations for High School Chemistry 2013 American Chemical Society

American Chemical Sociey

Energy Foundaions for High School Chemisry

Copyrigh 2013 by he American Chemical Sociey. All righs reserved.

Permission is graned in advance or reproducion or classroom use.Please include Reprined wih permission romEnergy Foundaions orHigh School Chemisry, Copyrigh 2013, American Chemical Sociey.

Te aciviies described in his book are inended or sudens under he direc supervisiono eachers. Te American Chemical Sociey canno be held responsible or any accidens or

injuries ha migh resul rom conducing he aciviies wihou proper supervision, rom nospecifically ollowing direcions, or rom ignoring he cauions conained in he ex.

American Chemical Sociey Saff

AuhorsMichael J. innesand

Erica JacobsenMelanie Rock

Adam M. Boyd

Educaion Division Direcor, Mary Kirchhoff

Assisan Direcor o K12 Educaion, erri aylorConen Reviewer,Dr. Jerry BellCopy Edior, Kelley Carpener

Saey Review, David Kaz


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2013 American Chemical Society Energy Foundations for High School Chemistry 3

SAFETYImportant Notice

Energy Foundaions or High School Chemisryis inended or use by high school sudens in heclassroom laboraory under he direc supervision o a qualified chemisry eacher. Te experi-

mens described in his book involve subsances ha may be harmul i hey are misused or i heprocedures described are no ollowed. Read cauions careully and ollow all direcions. Do nouse or combine any subsances or maerials no specifically called or in carrying ou invesiga-ions. Oher subsances are menioned or educaional purposes only and should no be used bysudens unless he insrucions specifically so indicae.

Te maerials, saey inormaion, and procedures conained in his book are believed o be reli-able. Te inormaion and hese procedures should serve only as a saring poin or good labo-raory pracices, and hey do no purpor o speciy minimal legal sandards or o represen hepolicy o he American Chemical Sociey. No warrany, guaranee, or represenaion is made byhe American Chemical Sociey as o he accuracy or specificiy o he inormaion conainedherein, and he American Chemical Sociey assumes no responsibiliy in connecion herewih.Te added saey inormaion is inended o provide basic guidelines or sae pracices. I canno

be assumed ha all necessary warnings and precauionary measures are conained in he docu-men or ha oher addiional inormaion and measures may no be required.

Safety and Laboratory Activity

InEnergy Foundaions or High School Chemisry, you will requenly complee he laboraory

invesigaions. While no human aciviy is compleely risk-ree, i you use common sense, as wellas chemical sense, and ollow he rules o laboraory saey, you should encouner no problems.Chemical sense is jus an exension o common sense. Sensible laboraory conduc won happen

by memorizing a lis o rules, any more han a perec score on a writen drivers es ensures anexcellen driving record. Te rue drivers es o chemical sense is your acual conduc in helaboraory.

Sudens will see he goggle icon (a righ) when hey should be wearing hem.Sudens should coninue o wear goggles as hey work hrough an invesigaionand unil hey are compleely finished in he laboraory. Te erm goggles usedin he saey secion o each lesson reers o chemical splash goggles as shown inhe icon accompanying every aciviy in he lessons.

Sudens will see he red cauion icon (a righ) when here are subsances orprocedures requiring special care. I is especially imporan or he insrucor osupervise he usage o maerials or execuion o procedures noed wih his icon.


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ABOUT THIS TEXT

The Energy Foundations Project

Energy Foundaions or High School Chemisryis a collecion o resources ha you can use o each

he big ideas abou energy in your high school chemisry classroom. Feauring lab invesigaions,demos, suden readings, and mulimedia, i provides educaional pieces ha will suppor yourexising curriculum.

Alhough he resources are organized ino our secions (lised on page 6), his is only one sug-gesed way o sepping hrough he conen. Please be encouraged o skip around and choose hepieces rom each secion ha bes mee he educaional needs o your specific classroom.

Likewise, he organizaion o resources wihin a secion is mean only as a guide. aken ogeher,every piece o conen is inended o be used la care, wih sufficien flexibiliy o accommodae

varying approaches and needs.

The Authors

Energy Foundaionswas developed and writen by Michael J. innesand, Erica Jacobsen, MelanieRock, and Educaion Division saff a he American Chemical Sociey. Michael, Erica, and Mela-nie have decades o experience in chemisry eaching and science educaion consuling. You canfind more resources rom he ACS Educaion Division a www.acs.org/educaion.

The SponsorAll o he resources romEnergy Foundaionsare made possible by generous unding rom BP.


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WELCOME FROM THE AUTHORS

Dear Fellow Educaors,

Welcome o he new High School Energy Module rom he American Chemical Sociey! In

his bookle and is companion websiehighschoolenergy.acs.orgyou will find conen orhigh school chemisry eachers, including animaions, videos, and aricles ha each conceps oenergy in he conex o laboraory invesigaions.

Te idea or his projec sared wih a gran rom BP and included eacher surveys and iner-views. eachers were asked abou which opics and conen ypes would be mos beneficial.

Using his inpu, our curriculum developers came up wih aciviies divided ino our areas:

Wha is Energy? (ypes o energy and how we experience hem)1.

How Do We Use Energy? (Te energy in chemical processes and everyday lie)2.

How Can Energy Change? (Conservaion o energy and energy ranser)3.

Wha Teories Explain Energy? (Termodynamicshe heory o energy)4.

For each o hese areas, we developed a se o lab invesigaions, videos, demonsraions, andbackground reading maerials.

In order o make hese maerials as widelyuseul as possible, we sough o align hem

wih he Nex Generaion Science Sandards,which were based on he Naional ResearchCouncils Framework or K12 Science Educa-ion. Alhough weve presened our ideas in aslighly differen order and descripion, hereis a close mach beween he ACS High SchoolEnergy Module and he NGSS.

Each o he elemens o he module can be

used alone or as a complee se o aciviies,depending on your curriculum needs. In addiion, many o he aciviies are presened in aorma ha can be downloaded and modified o mee your specific requiremens.

We are confiden you will find hese maerials useul, and we hope you enjoy using hem. I youhave any commens abou hese maerials, please eel ree o conac us a [email protected].

Cheers!Michael

Michael J. innesand, lead curriciulum developer


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TABLE OF CONTENTS

What is Energy?1.

Types of energy and how we experience them

Lab InvesigaionExploring Energy .............................................................................. 8VideoWha is Energy? .................................................................................................. 19VideoTe Energy o oys ............................................................................................ 22ChemMaters ReadingTe Amazing Drinking Bird! ............................................... 25ChemMaters ReadingTermomeers ....................................................................... 27

How Do We Use Energy?2.

The energy in chemical processes and everyday life

Lab InvesigaionCombusion & Burning ................................................................ 32 DemoSoda Can Seam Engine ................................................................................... 43Lab InvesigaionPreparaion & Combusion o Biodiesel ................................... 46DemoElecrolysis o Waer .......................................................................................... 57

Videoemperaure & Energy ...................................................................................... 61ChemMaters ReadingTe Explosive Hisory o Nirogen ..................................... 64

How Can Energy Change?3.

Conservation of energy and energy transfer

Lab InvesigaionTe Energy o Evaporaion ........................................................... 68Lab InvesigaionTe Energy Efficiency o Heaing Waer ................................... 78Lab InvesigaionExohermic, Endohermic, & Chemical Change ..................... 91

VideoExohermic & Endohermic Reacions ........................................................ 115VideoMee a BP chemis ........................................................................................... 118

What Theories Explain Energy?4.

Thermodynamicsthe theory of energy

Lab InvesigaionEnropy & Enhalpy Changes .................................................... 121Lab InvesigaionEnergy & Enropy o a Sreched Rubber Band .................... 142ChemMaters ReadingWhy Cold Doesn Exis ..................................................... 151


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What is Energy?

Wha is energy? Mos o us have a eeling ha we undersand energy and recognize iwhen we see i, bu coming up wih a ormal definiion migh be harder or us o do. Inhis secion we inroduce he concep o energy by having sudens invesigae a variey ooys. Tey are given a lis o he various caegories and ypes o energy and are asked oorm a working definiion o wha energy means. A series o videos and reading selecions

help hem solidiy heir definiion ino an auhoriaive version.

Lab InvesigaionExploring EnergyVideoWha is Energy?VideoTe Energy o oysChemMaters ReadingTe Amazing Drinking BirdChemMaters ReadingTermomeers


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Exploring Energy | A Lab Investigation

Summary

Energy as a concep is boh amiliar and vague. Mos sudens have a good operaional definiiono energy, bu may no be able o verbalize a good ormal definiion. Te purpose o his lab is o

solidiy suden ideas o energy by providing several examples o objecs whose use or operaioninvolve energy and provide clear definiions ha describe wha energy is and is no.

Objective

Sudens will explore he definiion o energy by making careul observaions abou simple oysha illusrae basic principles o energy.

Safety

Goggles or saey glasses should be worn when working wih any maerials ha can spill

or splash or hose ha can pop or jump wih any orce.Do no cu or ear open ligh sicks, chemical hand warmers, or cold packs. I any maeri-als leak rom hese iems, clean up spills wih waer. Wash any chemicals rom your skin

wih waer.Jumping discs and poppers can reac wih significan orce o cause injury o he ace andeyes. Keep your ace away rom hese objecs.

Materials for Each Group

Here is a sample lis. Collec your own devices based on wha you have available and your bud-ge. Consider asking sudens o bring in a household device ha involves energy.

Batery-operaed flashlighClock wih glow in he dark aceSmall mechanical oy (like a wind-up car)Drinking bird oyChemiluminescen glow or ligh sickChemical hand-warmerEmergency cold packs

Bi-meallic jumping discsPolymer or poppers oy

A hand-wound or spring-operaed music box

Time Required

One class period, approximaely 4550 minues.


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Lab Tips

A number o household objecs and oys have been suggesed or use in his invesigaion, bu hefinal selecion can be modified o whaever you have on hand. ry o choose objecs ha displaya variey o orms o energy. Since his is a ormaive ype o invesigaion, i is no criical hasudens are perec in heir assessmens o he ype o energy presen or he ransiions ha ake

place. Raher, use heir observaions and class discussion o clariy heir undersanding o heconcep.

Pre-Lab Discussion

Tis lab is basically an inormal ormaive assessmen o wha sudens know abou energy. I is agood chance o clariy suden ideas abou energy by ideniying wha is and wha is no consid-ered o be energy.

Integrating into the Curriculum

Tis invesigaion could fi ino a uni on hermochemisry.


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PREPARING TO INVESTIGATE

Wha is energy? Mos o us have a eeling ha we undersand energy and recognize i when wesee i, bu coming up wih a ormal definiion migh be harder or us o do. Here are some o he

basic conceps associaed wih a definiion o energy:

Energy is required o make hings change.Energy is he abiliy o do work. Te kind o work we are alking abou is no like going oa job or doing chores. We are alking abou work as defined in he physical sciences.

Work is he applicaion o a orce o move an objec in he direcion o he orce, such aswhen you pedal a bicycle or an elecric moor lifs an elevaor.A orce is an influence ha can cause an objec o move or sop an objec ha is alreadymoving. Tink abou how brakes mus be applied o slow an auomobile, or how youhrow a ball hard o ge i o go as ar as possible.Moion is a change in disance over ime.

One o he easies ways o recognize energy is o know he various orms i can ake.All energy alls ino wo caegories, kineic and poenial energy. Kineic energy is he energy omoion. Tink abou he energy in a brick. Which has more energy, a brick lying on your oo,or a brick dropped on your oo? Te dropped brick has more kineic energy.

Energy is no an objec in iself, raher, energy refers o a condiion or sae of an objec.

Te main ypes o kineic energy are:

Elecrical Energy Te energy associaed wih he movemen o elecrons. When elec-rons flow hrough wires, we call i elecriciy.Termal Energy Te energy ha resuls rom he movemen o aoms and moleculesand is relaed o heir emperaure. Te aser he paricles move, he greaer he amoun oenergy and he higher he emperaure.Movemen Energy When objecs or maerials flow or move rom one place o anoherhey produce energy, such as waer flowing hrough a dam.Sound Energy Produced by he periodic movemen o mater in a medium. Sound can

ravel hrough air, solids and liquids, bu no hrough a vacuum, because here is no materhere.Radian Energy A ype o kineic energy ha includes ligh rays, X-rays, radio waves,microwaves, and any oher par o he elecromagneic specrum. Elecromagneic wavesare a resul o he vibraion o charged paricles such as elecrons. Microwave ovens useradian energy o hea ood by causing he waer molecules in he ood o vibrae.


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Poenial Energy is energy ha is sored. In he example above, beore i ell on your oo, heraised brick had poenial energy because o is posiion. When i ell, his energy was converedo kineic energy o moion.

Here are he main ypes o poenial energy:

Chemical Energy Chemical bonds hold aoms ogeher. I akes energy o break hesebonds, and energy is released when new bonds orm.Mechanical Energy Examples include a clock ha is powered by a wound-up spring, oran arrow sho rom a bow. Wih his ype, energy is sored in he mechanical device by heapplicaion o a orce, such as when we wind he clock or pull he bow back.Nuclear Energy When he nucleus o an aom splis or is used o anoher nucleus,energy can be released. I is he ype o energy ha powers our sun and is ound in nucle-ar power plans.Graviaional Energy Tis is he energy associaed wih an objecs posiion in a gravi-aional field. A ball resing a he op o a ramp has higher poenial energy han when ihas rolled o he botom. Waer behind a dam has higher poenial energy han when i hasflowed o he river below. In each case he poenial energy is due o relaive posiion inhe graviaional field.

GATHERING EVIDENCE

You will be provided wih a number o oys and oher common householdobjecs. Te objecs can include a flashligh, a clock wih a glow in he dark

ace, a small mechanical oy, a drinking bird, a ligh sick, a hand-warmer or emer-gency cold packs, poppers, or a music box, among ohers. Your eacher may ask

you o bring in a household objec ha involves energy.

For each o our objecs, operae he device and wrie a complee descripion abou wha youobserve. Be sure o include deails such as sounds, movemens, iming, and any changes younoice. I you are unclear abou how o operae any o he objecs, ask your eacher o show youhow. Your eacher may choose o demonsrae some o he examples or he enire class.


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Name of objec Descripion of operaion

1.

2.

3.

4.


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ANALYZING EVIDENCE

o analyze wha you saw or each o he objecs, you need o consider wha kinds o energy wereinvolved. Using he ypes o energy lised in he Preparing o Invesigae secion on page 10, lisall he kinds o energy you believe are involved in he operaion o each o he objecs.

Your eacher may ask you o work in small, collaboraive groups o complee his secion.

Name of objec Kind(s) of energy involved

1.

2.

3.

4.


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INTERPRETING EVIDENCE

Alhough some o he oys or objecs may have appeared o run ou o energy, one o he basicrules o science is ha energy canno be creaed or desroyed. I only changes rom one ormo anoher. Tink back o your observaions and analysis o he household iems and speculaeabou how energy changed in each o he objecs. In some cases here may have been muliple

ransiions.

Name of objec Describe he kinds of energy ransiions you observe

1.

2.

3.

4.


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REFLECTING ON THE INVESTIGATION

How did you deec he ypes o energy you observed in his invesigaion? Which ypes1.did you eel? Which ypes did you hear? Which ypes did you see? Lis any oher ways

you deeced energy.

One definiion o energy given in his lab was energy is he abiliy o do work. Consider-2.ing all he objecs you observed in his lab, record any examples o work ha was done.

Given he definiion o orce (an influence ha can cause an objec o move or sop mov-3.ing) ideniy some examples o where orce was applied in his invesigaion.

Based on your experience, wrie a definiion o energy in your own words. Also include4.some examples o hings ha are NO energy.

Saring wih he sun and ending wih you making a piece o oas a home, wrie down as5.many ypes o energy and energy ransiions as you can ha go ino your abiliy o have a

piece o bread and oas i.Ofen when he word energy is used, i reers o commercial producion o help power6.our homes. Lis he major ypes o energy used in commercial power plans.


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TEACHERS KEY

Gathering Evidence

Only one sample is given o demonsrae ypical answers. Te resuls will vary, based on hecollecion o objecs you provide o he class.

Name of objec Descripion of operaion

Bi-meallic jumping disc

Te jumping disc is a shallow dome made om a specialbi-meallic piece o meal, like he mechanism o many her-mosas. When i is warmed o abou body emperaure, youcan click i ino is loaded posiion (dome invered) and hencareully place i on a hard surace. When i cools down oroom emperaure, i suddenly snaps back ino he old posi-

ion, and simulaneously jumps high up in he air.

Analyzing Evidence

Name of objec Wha kind(s) of energy do you observe?


Termal energy is ranserred o he cool disc as i is warmedby my humb and fingers unil i is warmed o abou bodyemperaure. I observed mechanical energy as I snap he

disc ino is loaded posiion and hen careully place i on ahard surace.

When i cools down o room emperaure, i suddenly releasesis sored poenial energy and snaps back ino he old posi-ion, and simulaneously jumps high up in he air. I jumpsseveral hundred imes is own heigh, and I observed kineicor moion energy.


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Interpreting Evidence

Name of objec Describe he kinds of energy ransiions you observe


I observed chemical energy om my meabolism creaing her-mal energy, which was ranserred o he disc. I used mechani-

cal energy o click he disc ino is loaded posiion, creaingpoenial energy. As he disc popped i convered poenialenergy ino kineic energy as i jumped off he desk. When hedisc ell back o he desk i ranserred is kineic energy inohermal energy by slighly warming up he deskop (alhoughhis is difficul o observe, I assumed i occurred).

Reflecting on the Investigation

How did you deec he ypes o energy you observed in his invesigaion? Which ypes1.did you eel? Which ypes did you hear? Which ypes did you see? Lis any oher ways

you deeced energy.

Sudens will likely repor examples o all he ypes o energy lised above, including nuclearenergy (some glowing clock aces use riium or promehium o creae he glow).

One definiion o energy given in his lab was energy is he abiliy o do work. Consider-2.ing all he objecs you observed in his lab, record any examples o work ha was done.

Work is any orce applied over a disance. In chemical sysems i involves elecrical work (mov-ing elecrons in a wire as by a batery) or work o expansion (volume expanding as a resul o achemical reacion, as when bubbles are ormed in a reacion o baking soda and acid).

Given he definiion o orce (an influence ha can cause an objec o move or sop mov-3.ing) ideniy some examples o where orce was applied in his invesigaion.

Many examples are presened, such as he spring driving he mechanical oy, using your fingerso snap he popper ino is loaded posiion, and so on.

Based on your experience, wrie a definiion o energy in your own words.4.

Suden answers will likely echo he definiions given in he firs par o his lab. Encourage su-dens o pu he ideas in heir own words.

Saring wih he sun and ending wih you making a piece o oas a home, wrie down as5.many ypes o energy and energy ransiions as you can, ha go ino your abiliy o makeoas.

Te sun provides radian energy or whea plans o grow, and he whea plan sores he solar


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energy in seeds via phoosynhesis o creae chemical poenial energy. Radian solar energypowers he waer cycle, giving rivers ha can urn he kineic energy o moving waer ino elecri-cal energy. Household elecrical energy moves hrough high-resisance heaing elemens in heoaser and is convered ino hermal energy.

Ofen when he word energy is used, i reers o commercial producion o help power6.

our homes. Lis he major ypes o energy used in commercial power plans.Te main sources o our elecriciy are:

Coal and naural gasHydroelecric dams

NuclearWindSolar

Post-Lab Discussion

Use he pos-lab discussion o lisen o suden observaions and use a group discussion o clariyany misconcepions abou energy.

Additional Resources

Termodynamics, Real-Lie Applicaionshtp://bi.ly/highschoolnrg1

U.S. Deparmen o Energy, Secondary Energy Inobook, Aciviies and Background orHigh School Sudenshtp://bi.ly/highschoolnrg2

Noe: Even in some o hese official websies, here is a endency o misrepresen hea as some-hing ha is conained by an objec and flows beween one objec and anoher.

Objecs/sysems do no conain hea. Te moion o molecules is no hea. Te erm heaconen is hisoric and archaic (even hough i unorunaely coninues in use) and comes roma ime when hea was visualized as a fluid called caloric.

As a corollary, hea does no flow. Hea is a measure o he energy ha is ranserred rom oneobjec o anoher due o a difference in heir emperaures. Te energy ranserred is ofen calledhermal energy, since i is dependen on here being a emperaure difference. Te orm o heranser is conducion and radiaion. Is okay o call he amoun o energy ranserred heaas long as we are clear ha hea is a number (wih unis) ha is no ound wihin he objecshemselves, bu is a measure o a process. Is bes o call atenion o he process by using heaas a verb insead o a noun, as in When I heaed he soup, i go hoter; is emperaure wen up.


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What is Energy?| A Video

Tis video defines energy and explores some o is mos common orms. I can be used as a supplemeno an invesigaion, or may sand on is own o inroduce a lesson or exend suden learning.

highschoolenergy.acs.org/wha-is-energy/wha-is-energy.hml

Video Transcript

Britny

Wha is energy? Mos o probably undersand he concep o energy, or a leas we can recognizei when we see i.

Chris

Here are some basic conceps ha will help us define energy. Firs, energy is required o makehings change. For example, o change his No. 2 pencil rom one useul wriing uensil ino woless useul pieces, we need o use energy.

Britny

Energy is he abiliy o do work. Bu were no alking abou going o work or doing your chores,were alking abou work as defined in he physical sciences. Work is he applicaion o a orce omove an objec in he direcion o he orce. Like, when you pedal a bicycle, or when an elecric


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moor lifs an elevaor. Energy is conserved. So, wha does ha mean? I means ha one orm oenergy may be ransormed ino anoher orm, bu he oal amoun o energy remains he same.In oher words, energy canno be creaed, nor can i be desroyed.

Chris

One o he easies ways o recognize energy is o know he differen orms i can ake. All energyalls ino wo caegories: poenial and kineic energy. Poenial energy depends on he posiiono an objec or he arrangeme o is consiuen pars. Kineic energy is he energy o moion.Tink abou he energy o a brick resing on your oo compared o a brick being dropped on

your oo. Te moving brick has more kineic energy, which you become painully aware o wheni ransers some o ha energy ono your oo. When boh bricks are resing on your oo, heyhave he same poenial energy.

Britny

Tere are our main ypes o poenial energy. Firs, we have chemical energy. Chemical bondsholds aoms ogeher. I akes energy o break hese bonds and o move aoms urher apar.Energy is released when new bonds orm and aoms come closer ogeher. Chemical energy is

where he energy in our ood comes rom. Our body digess ood, like his sandwich, and useshe energy o do hings.

Anoher ype o poenial energy is mechanical energy. Mechanical energy is sored in a deviceby he applicaion o a orce, like he sored energy in a pulled bowsring. Once i is released,sored energy is convered ino kineic energy.

wo oher ypes o poenial energy include nuclear energy and graviaional energy. Gravia-ional energy is relaed o an objecs posiion in a graviaional field. Tis ennis ball has a higherpoenial energy up here han when i alls o earh.

Chris

OK, enough abou poenial energy. Les alk abou kineic energy. Firs o all, heres hydro orwind energy. All objecs in moion have kineic energy ha can be ranserred o oher objecsby collisions. For example, he movemen o air can urn windmills o pump waer or produceelecriciy.

Speaking o elecriciy, heres also elecrical energy. Elecrical energy is he energy associaedwih he movemen o ions and elecrons. When elecrons flow hrough wires, we call i elecric-iy. In addiion, heres radian energy, which comes rom ligh waves, x-rays, and microwaves, andis all around us.

And hen, heres hermal energy. Termal energy is he energy ha resuls rom he movemeno aoms and molecules and is relaed o heir emperaure. Te aser he paricles move, hegreaer he amoun o energy, and he higher he emperaure.


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Sound energy is produced by he periodic movemen o mater in a medium. Sound can ravelhrough gases, solids, and liquids. Prety much any mater, bu no hrough he vacuum o space,

because heres no mater here. So you know ha old sci-fi movie line abou how in space, noone can hear you scream? oally rue. And a litle erriying.

So here you have i, he main ypes o poenial and kineic energy. All his alk abou energymakes me wan o absorb some.

Britny

Is ha my sandwich?!

Chris

Uhh ... poenially ...


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The Energy of Toys| A Video

Tis video explores he chemisry behind simple oys ha showcase energy changes. I can supplemenan invesigaion, or may sand on is own o inroduce a lesson or exend suden learning.

highschoolenergy.acs.org/wha-is-energy/wha-is-energy.hml

Video Transcript

Wha, exacly, is energy? Because we can see i, coming up wih a ormal definiion or energycan be ough. However, we can see how energy is ranserred rom one orm o anoher. Forexample, pu a batery in a flashligh and soon we ge ligh ou he oher end.

Energy is he abiliy o do work and make hings change.

Bes o all, we can undersand energy by playing wih some classic oys.

Mee my riend revor, he amazing drinking bird. Te amazing drinking bird is a oy ha hasbeen around or over 50 years. I looks like a bird, and will bob up and down and appears odrink ou o a cup o waer placed in ron o i.

Bu how does i work?


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Well, he amazing drinking bird is made ou o glass and conains a red liquid. Te head and ailare bulbs conneced by a narrow glass ube. Te only way or liquid o move beween he headand he ail is hrough his narrow ube. A el-like uzzy maerial covers he head and beak.

Te red liquid inside he bird is acually mehylene chloride, also known as CH2Cl2. Mehylenechloride is a very volaile liquid, which means i evaporaes easilyeasier han waer. Mos o heair has been removed rom he inside o he bird beore he liquid is added, making i even easieror he liquid o vaporize.

Weting he head o he bird sars he acion. Afer weting he head, he red liquid inside hebird slowly begins o rise rom he botom bulb up o he head. Tis changes he cener o graviyand he bird begins o ip down ino he cup o waer. As he bird ips over, he liquid hen flows

back ino he botom bulb, lowering he cener o graviy and he bird sands uprigh. Ten heprocess repeas.

So, wheres he chemisry here?

Well, when he birds beak ges we, i causes he inside o he head bulb o cool. As he inside ohe head cools, he mehylene chloride in he head changes rom a gas o a liquid, lowering he

vapor pressure inside he head. Because he vapor pressure in he ail bulb is now greaer han hevapor pressure in he head bulb, he liquid is pushed up ino he head bulb.

Anoher nea oy ha can each us abou energy is called a jumping disc.

Te disc is abou an inch in diameer and made o hin layers o wo differen ypes o meals. Iis slighly concave. o make i jump, he disc is aken in he hand and rubbed beween he humband fingers. Tis warms he disc and makes i click ino a convex shape.

When he disc is hen placed on he able, i is sill or a momen, hen i jumps ino he air a ooor more.

So where does he energy come rom o make he disc jump?

Tese discs are made rom wo differen ypes o meal, sandwiched ogeher ino a very hinlayer. One o he layer ends o expand when is emperaure increases while he oher layer doesno. As he disc is warmed, he emperaure sensiive srip o meal grows slighly larger whichcauses he disc o snap rom a concave shape o a convex shape.

When he disc is placed on he slighly cooler counerop, his same layer begins o conrac, andhe disc snaps back ino is original shape. Te orce o his ransormaion launches he disc inohe air.


24/152


So how is energy involved in his oy?

Termal energy is ranserred rom your warm hand o he cooler disc. Tis warms he mealsrips in he disc isel. As he emperaure increases, he aoms in he meal move aser andspread urher apar. Te iner layer resiss change, due o he way is aoms are arranged.

So, when he warm disc changes is shape, i has a higher poenial energy. When i snaps back ois original shape, his poenial energy is convered ino kineic energy and he disc jumps.

Alhough were more likely o ocus on he bateries in our smar phones, hese simple oys are aun reminder ha energy is all around us.

Isn ha righ, revor?


25/152


Chapter 1, Student Reading 1: The Amazing Drinking Bird

Energy as a concep is boh amiliar and vague. Mos sudens have a good operaional definiiono energy, bu may no be able o verbalize a good ormal definiion.

he drinking bird is a mesmerizing little

science toy that has fascinated young

and old for more than 50 years. It is

also known as the happy bird, the

dippy bird, the happy dippy bird, and

other variations on this same theme. It

looks like a bird and will bob up and

down as it appears to drink out of a glass ofwater. As long as it can reach the water, it will

bob up and down indefinitely. The drinking

bird consists of two elongated glass bulbs that

are connected by a straight glass tube extend-

ing well into the interior of the bottom bulb.

The only way any substance can pass between

the two bulbs is through this narrow glass

tube. The top bulb is covered with a porous

feltlike material that also makes up the beak.

On top of the head is a plastic top hat, which is

only for decoration. Taped to the bottom

chamber are tail feathers, which help it to

maintain balance. The whole thing is sus-

pended from plastic legs, with a horizontal

piece of metal that acts as a pivot, allowing it

to bob up and down.

Inside, the drinking bird is a highly

volatile liquid known as methylene chloride

(CH2Cl2). Since methylene chloride is color-

less, coloring must be added to enhance the

visual effect. This liquid is also highly volatile,

meaning it evaporates rapidly due to weak

intermolecular bonds in the liquid state. Its

boiling point is 39.7 C (103.5 F), and its

vapor pressure at room temperature is 46 kilo-pascals (compared to only 3 kPa for water).

Methylene chloride is somewhat toxic, so if a

drinking bird breaks, care must be exercised in

cleaning it up. Methylene chloride is com-

monly used as an industrial cleaner,

degreaser, and paint remover.

After the methylene chloride is added by

the manufacturer, most of the remaining air is

then vacuumed out. Because a near vacuum

now exists within the bird, the highly volatile

liquid readily evaporates until the space above

the liquid is saturated with vapor. At this point,

a dynamic equilibrium is established within thebird between the liquid and the vapor above it.

Once equilibrium is established, anytime a

molecule evaporates, another molecule will

condense, resulting in an overall constant

amount of vapor within the bird as long as the

temperature stays constant.

To activate the drinking bird, his head is

dipped into a glass of water, and he is then set

upright in such a position that when he tips his

beak, he will be able to reach into the glass of

The

AmazingDrinking Bird!

T

By Brian Rohrig


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water. Once the head is wet, a strange thing

immediately begins to happen. Like magic, the

fluid begins to rise upward into the head, until

his head fills with liquid. The head then

becomes top heavy as the center of gravity of

the bird is raised. The bird then topples over,

takes another drink. As the bird tips over, the

liquid flows back to the bottom bulb, restoring

the low center of gravity. The bird resumes itsupright position, beginning the whole process

all over again.

To understand what makes the fluid rise

within the bird, think about what happens

whenever your own head gets wet. As long as

the relative humidity is not 100%, the water

will immediately begin to evaporate. And evap-

oration always causes cooling, because it is an

endothermic process. Thats why you sweat

when you get hot; its not the sweating itself

that cools you, but rather the evaporation of

the sweat from your body. Any phase change

that requires bond breaking will be endother-mic, because energy is required to break

bonds. This energy is drawn from the sur-

roundings, thereby causing the temperature of

the surroundings to decrease.

Because water evaporates from the

head of the bird, the head imme-

diately begins to cool. This is the

most crucial point in understand-

ing how the drinking bird works.

If you could cool the head

another way, the drinking bird

would work just the same. When

the head begins to cool, some of

the vapor within the head will

condense into tiny droplets of liq-

uid. A similar process occurs at

night when water vapor con-

denses out of the air as it cools,

forming dew on the ground.

Because some of the vapor con-

denses within the top chamber of

the bird, there is now less vapor pressure in

the top bulb. Less vapor means less pressure.

But the vapor pressure within the bottom bulb

has not changed. Because the vapor pressurein the bottom bulb is now greater than the

pressure in the top bulb, the liquid is forced

upward into the top chamber. (Dont say the

liquid is sucked up into the top chambersci-

ence never sucks!) Once the bird tips over,

vapor from the bottom travels to the top until

the pressure in both spheres equalizes and the

bird begins the process all over again.

To understand how this pressure differ-

ential can cause the fluid within the bird to

rise, consider what happens when you use an

ordinary drinking straw. When you suck fluid

up into the straw, you are creating a region of

reduced pressure within the straw. Because

outside air pressure is

greater, it pushes

downward on

the surface of

the fluid, forc-ing it up the

straw.

Not only is the drinking bird educational,

but it can also provide hours of entertainment.

Many science museums feature displays of

drinking birds. No science classroom would becomplete without one. The amazing drinking

bird has even appeared in a 1995 episode of

The Simpsons, where Homer positions a

drinking bird in front of his keyboard to help

monitor the controls at the Springfield nuclear

power plant. The artist Daniel Reynolds spent a

small fortune and several years developing an

art exhibit comprising a whole flock of giant 6

1/2 feet tall drinking birds, each weighing

3,000 times more than an original drinking

bird. They had to be made with a special vac-

uum attachment in order to work properly.

There are many variations on the drinking

bird. They come in a variety of styles and sizes.

There is even a drinking giraffe! The very pop-

ular, but falsely named hand-boiler is noth-

ing more than a drinking bird that is

stripped down to the bare essentials. It

works either by cooling the top orwarming the bottom.

The next time you need a

unique gift for the person who

has everything, consider a

drinking bird. A quick

search on the Internet will

reveal a plethora of

sources. They especially

make great gifts for

science teachers!

Brian Rohrigis a chemistry teacher at Jonathan AlderHigh School in Plain City, OH. His article TheresChemistry in Golf Balls! also appears in this issue.

Additionalexperiments you canperform with the

drinking bird:1. Place a gallon-size freezer bag

over an operational drinking bird.He will almost immediately stop

drinking. Can you explain why?2. Have a drinking bird drink hot

water and then ice-cold water.Which will make the bird drinkfaster?

3. Have the bird drink a liquid witha higher evaporation rate thanwater, such as rubbing alcohol.Does the drinking bird drinkfaster?

4. Instead of cooling the head,heat the body, either with yourhand or a heat lamp. Does thedrinking bird work?

5. If you have a spare drinking birdthat you dont mind disfiguring,paint the top bulb silver and thebottom bulb black. Place in asunny windowsill and watch itbob up and down! No waterrequired.

Cool headRed

absorbantmaterial

Goofytop hat

BirdsDrink ofChoice

H2O

Feet forbalance

Feathersfor style

region of

lowerpressure

region ofhigher

pressure

highlyvolatile

liquid


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e have all used a ther-

mometerto check for

a fever, record data dur-

ing a chemistry lab, or to

help us decide how to

dress before leaving for school in the morn-

ing. But have you ever thought about how a

thermometer works? And when you measure

temperature, just what exactly are you

measuring?

The prefix thermo- refers to heat. Ther-

modynamics is the study of heat. A thermos

either keeps heat in or out. You wear thermal

underwear to prevent body heat from escap-

ing. Despite its name, however, a thermome-

ter does not actually record heat, but rather

temperature. Temperature and heat are two

radically different concepts.Temperature is a measure of the average

kinetic energy of the molecules within a sub-

stance. When you record the temperature of

something, you are making a statement about

how fast the molecules are moving. When you

are waiting for a bus in the morning in the

middle of January, instead of saying, Boy, its

cold out here this morning, it would be more

accurate to say, Boy, the molecules in the air

are moving quite slow this morning!

Heat vs.

temperatureHeat is a little trickier to define. Heat

refers to the movement of energy from a

substance of high temperature to one of low

temperature. Heat always refers to energy in

transit. A substance can have a high temper-

ature, but little heat available to transfer. A

drop of boiling water contains less actual

heat than a bathtub full of water at a lower

temperature. Temperature is a measure of

only the average kinetic energy of molecules,

but because heat depends on the total

energy, there is not a simple, universal rela-

tion between the two.

Heres an everyday example that helps

to illustrate the difference between heat and

temperature. Consider ice: when you cool a

drink using ice, a lot of heat flows from the

drink into the ice (so the drinks temperature

falls). But the temperature of the ice does not

rise, it stays at 0 Cthe heat goes into

breaking the interactions between water mol-

ecules to melt the ice (at 0) to form water

(still at 0). Ice and water at 0 have the

same temperature but very different amounts

of heat.

Temperature scalesIn the United States, most thermomete

for everyday use are calibrated in degrees

Fahrenheit. Most of the rest of the world me

sures temperature in degrees Celsius. At onpoint during the 18th century, there were

nearly 35 different temperature scales in us

Many scientists felt the need to devise a uni

form temperature scale that would meet wid

spread acceptance.

One temperature scale that met with

some success was the Romer scale, which

was first used in 1701. This temperature sc

was invented by Ole Christensen Romer, a

Danish astronomer whose biggest claim to

fame was measuring the speed of light in

1676. His temperature scale set the boiling

point of water at 60 and the freezing point 7.5. The lowest temperature you could

achieve with a mixture of salt and ice was 0

Because most people from that time period

were not too concerned about the temperat

of ice and salt, this scale was destined for th

dustbin of history.

Daniel Gabriel Fahrenheit, a German

physicist, published an alternate scale in

1724. Borrowing from the work of Romer,

WBy Brian Rohrig

You are feeling sick.

You call the doctor and

she wants to know the

average kinetic energy

of your bodys molecules.

What will you do?

JUPITERIMAGES


28/152


he set 0 F as the lowest temperature that

could be achieved with a mixture of salt, ice,

and ammonium chloride. (It is unclear

whether Romer also used ammonium chloride

in his experiments, as many of his records

were destroyed in a fire.) Fahrenheit set the

freezing point of water at 32 and the body

temperature of a person at 96, which he

determined by measuring the temperature

under his wifes armpit. Each degree of hisscale corresponded to one ten-thousandth the

initial volume of mercury used in his ther-

mometer. To this day, there is considerable

controversy as to how Fahrenheit actually

arrived at his temperature scale. He never did

reveal exactly how he arrived at the reference

points for his thermometer, as he did not want

others to construct and sell the thermometers

he had spent much of his life perfecting.

His scale met widespread acceptance

because everyone could relate to it, since 0 F

and 100 F were the lowest and highest tem-

peratures typically experienced on any type of

regular basis in Western Europe. If the tem-

perature rose above 100, you knew it was

really hot. If the temperature dipped below 0,

you knew it was quite cold. Whether these

points were intentionally chosen to represent

these extremes or just happened to work out

this way is still being debated today. The

biggest problem with this scale was the freez-

ing and boiling points of water were set at 32

and 212, not exactly round numbers. This

was an issue not so much with the general

public, but rather with scientists, who tend toobsess over such things. However, others

have postulated that placing 180 degrees

between the freezing and boiling points of

water was not arbitrary but quite rational, as

this number represents the number of

degrees in half a circle.

To counter this problem, Swedish

astronomer Anders Celsius came up with

another scale in 1742, setting

the freezing and boiling points

of water at 0 and 100, with

100 divisions in between.

Hence, it was termed theCentigrade scale, since the

prefix centi- represents one-

hundredth. Celsius had ini-

tially set the freezing point of

water at 100 and the boiling

point at 0. This was later

reversed after his death. Most

countries that have adopted

the metric system of mea-

surement use

this temperature

scale, as it is

conveniently

broken down

into units of 10.

In 1948, the

Centigrade scale

was officially

designated theCelsius scale,

although some

people still use the outdated term.

The most scientific scale in use today is

the Kelvin, or absolute, temperature scale. It

was devised by British scientist William

Thomson (Lord Kelvin), in 1848. Because

temperature is a measure of molecular

motion, it only makes sense

that the zero point of your scale

should be the point where mol-

ecular motion stops. That is

exactly what the Kelvin scaleaccomplishes. 0 Kelvin (K) is

the point at which all molecules

stop moving. 0 K is known as

absolute zero, which has never

actually been reached. In 2003

at MIT, scientists came very

close to reaching absolute zero,

obtaining a frosty temperature

of 4.5 10-9 K.

The Kelvin scale is primarily used in sci-

ence, and temperature must be expressed in

Kelvin when solving many equations involv-

ing temperature, such as the gas laws. But it

tends to be too cumbersome for everyday

use, since the freezing point of water is 273 K

and the boiling point is 373 K.

Types of

thermometersEarly thermometers

The first thermometer in modern times

was a crude water thermometer believed to

have been invented by Galileo Galilei in 1593.

In 1611, Sanctorius Sanctorius, a colleague of

Galileos, numerically calibrated the ther-

mometer. Many of these first thermometers

used wine, as its alcohol content prevented it

from freezing and its red color made it easy to

read. However, these first thermometers were

very sensitive to air pressure, and functioned

as much as a barometer as they did as a ther-mometer. So eventually, all thermometers

were constructed of a sealed glass tube that

had all the air removed. Because

these vacuum tubes

were shut

WWW

.NPS

.GOV

Lord Kelvin

Anders Celsius

370

360

350

340

330

320

310

300

290

280

270

260

250

100

90

80

70

60

50

40

30

20

10

0

-10

-20

32

212

-459.67

100

0

-273.15

273.15

373.15

0

Kelvin Celsius Fahrenheit

Water boils

at sea level

Body temperature

96.6 F, 37 C

Water freezes

at sea level

Absolute zero all

molecular motion STOPS

210

200

190

180

170

160

150

140

130120

100

90

80

70

60

50

40

30

20

10

0

-10

JUPITERIMAGE

A comparison of three temperature scales.

CESA

RCAMINERO


29/152


off from the outside atmosphere, changes in

air pressure would not affect the temperature

reading. In 1709, Fahrenheit invented the alco-

hol thermometer, and in 1714, he invented the

first mercury thermometer. All thermometers

work according to the same basic principle:

objects expand when heated and contract

when cooled.

Bulb thermometersThe most common thermometer is the

bulb thermometer, which comprises a large

bulb filled with a liquid and a narrow glass

tube through which the liquid rises. All liquids

expand when heated and contract when

cooled (with the exception of H2O near its

freezing point; ice-cold H2O at 0 C contracts

until 4 C where it expands like other materi-

als), which explains why the liquid within a

thermometer rises as the temperature

increases and falls when it decreases. Mer-

cury was the liquid of choice for many years,

because it expands and contracts at a very

constant rate, making mercury thermometers

very accurate. However, because of concerns

about mercury toxicity, mercury has often

been replaced with alcohol that is colored red.

Mercury has a silver color. It freezes at

39 C, so it cannot be used if temperatures

get colder than this.

Bimetallic strip

thermometers

Another very commontype of thermometer is the

bimetallic strip ther-

mometer. This ther-

mometer comprises

two different metals,

such as copper and

iron, which are

welded together. Each

of the metals used has

a different coefficient of

linear expansion, or to put it

simply, these metals expand at

different rates. Connected to

this bimetallic strip is a

pointer, which points to the correct tempera-

ture on the face of the thermometer. Because

these metals expand at different rates, when

heated, the welded strip of metal will bend.

When cooled, it will bend in the opposite

direction. A variation of the bimetallic strip

thermometer is the thermostat used in homes

and automobile engines. These thermostats

are made of a thin bimetallic strip, which is

fashioned into a coil, making it more sensitive

to minor temperature fluctuations.

Infrared

thermometersA fascinating thermometer is the

infrared thermometer. This handheld device is

used by simply pushing a button as you point

it toward an object. A digital readout tells you

the temperature. All objects above absolute

zero are emitting

infrared radiation (IR)

an invisible (to

human eyes) form of

electromagnetic energy.

The infrared radiation

we emit is commonly

known as body heat.

The infrared thermome-

ter has a lens thatfocuses the infrared energy into a detector,

which measures the IR intensity and converts

that reading to temperature. Infrared ther-

mometers have a wide variety of applications.

They are used by firefighters to detect hot

spots in buildings and in restaurants to

ensure that served food is still warm. Infrared

thermometers are also used for determining

the temperature of a human body, automobile

engines, swimming pools, hot tubs, or when-

ever a quicksurface temperature is needed.

Pop upsYou are cooking

that Thanksgiving

turkey, and you

want to make

sure that the

inside of the

turkey is com-

pletely done. To

ensure that you

are not feasting on

undercooked bird,

you can use an inge-

nious device known

as the pop-up turkey

timer. This instrument is simply

stuck into the turkey, and when

the turkey is done, a red indicator

pops up (A). The little red indica-

tor is spring loaded (B) and is

held in place by a blob of solid

metal (C). When this metal reaches a temper-

ature of 85 C, which is the temperature of a

fully cooked turkey, it melts, causing the red

indicator to pop up.

This technology is similar to that used in

sprinklers found on the ceilings of many

buildings, which actually served as the inspi-

ration for the pop-up turkey timers. When a

certain temperature is reached, a metal com-

ponent within these sprinklers melts, activat-

ing the sprinkler. By mixing together differentmetals, a particular alloy can be created with a

desirable melting point. Pop-up timers can be

purchased for a wide variety of different types

of meat, from ham to hens. You can even buy

a pop-up timer for steak, which pops up in

increments indicating rare to well done.

And now for some-thing completelydifferent

Perhaps the most

unusual thermometerever invented is the

Galileo thermometer,

based on a similar

device invented by

Galileo. This instrument

does not look like a

thermometer at all, as it

is composed of several

glass spheres contain-

ing different colored

liquids that are sus-

pended in a cylindrical

A

B

C

Popup turkey timer

Infrared thermometer

WWW.P

ARANORMALGHOSTSOCIETY.O

RG

Galileo thermometer

GETTY

IMAG

ES

CESARCAMINERO


30/152


column of a clear liquid. Attached to each of

the colored spheres is a little dangling metal

tag with an engraved temperature. The tem-

perature is determined by reading the tag on

the lowest floating sphere. As the temperature

rises, the spheres will begin to fall one by

one. When the temperature falls, the spheres

will then rise one by one.

The liquid within each glass sphere is

composed of either colored water or alcohol.

Each of the spheres is of a slightly different

mass, and thus a slightly different density,

since the volume of each sphere is the same.

Each sphere differs in mass by about 0.006

grams. This difference is accomplished by

making each tag a slightly different mass.

The clear liquid surrounding the spheres is

an inert hydrocarbon-based oil, similar to

mineral oil. When this liquid is heated, it

expands, becoming less dense. Less denseliquids exert a lesser buoyant force, so the

most dense sphere will then sink. If the tem-

perature continues to rise, the molecules of

the surrounding liquid will continue to spread

apart from one another, causing more

spheres to fall. As the liquid cools, its mole-

cules come closer together, exerting a greater

buoyant force, causing the spheres to rise.

The spheres themselves do not expand or

contract nearly as much as the surrounding

liquid when heated or cooled, since they are

composed of glass, which hardly expands at

all when heated.Even though it looks nothing like a con-

ventional thermometer, the Galileo thermome-

ter still functions according to the same basic

principle as most other thermometers: sub-

stances expand when heated and contract

when cooled.

Whats the future for

thermometers?

Technology has come a long way since

Galileos day, but his thermometer to this dayhas a futuristic look to it. Another futuristic

thermometer that is available today is the

CorTemp thermometer. Developed by Dr.

Leonard Keilson of the Applied Physics Labo-

ratory of the Johns Hopkins University in con-

junction with NASA, the CorTemp

thermometer is swallowed, allowing accurate

temperature readings while it travels through,

or is stationed at some particular spot in the

body. The probe is enclosed in a small pill that

is taken internally, while the temperature read-

ings are recorded on a device that is moni-

tored externally.

No matter what device you use to take

your temperature when you have a fever, none

will make you feel better. But in this techno-

logically advanced world today, your choice of

thermometer might bring you a bit of wel-

comed distraction while measuring the aver-

age kinetic energy of your bodys molecules.

REFERENCES

Maddox, B. Nightmare of divided loyalties. Discover. June 2006, pp 2627.

Shactman, T. Absolute Zero and the Conquest of Cold. Houghton Mifflin Company: New York,1999.

INTERNET REFERENCES

Fahrenheit

http://en.wikipedia.org/wiki/Fahrenheit

How Pop-Up Turkey Timers Work

http://home.howstuffworks.com/pop-up-timer.htm/printable

How Thermometers Work

http://home.howstuffworks.com/therm.htm/printable

The History Behind the Thermometer

http://inventors.about.com/library/inventors/blthermometer.htm

Brian Rohrigteaches at Jonathan Alder High School in Plain City, OH. His most recent ChemMattersarticle,Glass: More Than Meets the Eye, appeared in the October 2006 issue.

The CorTemp system can measure and record the bodytemperature and/or heart rate of many athletes on the field duringpractices or competition. Once the probe is inside the gastro-intestinal tract, a crystal sensor vibrates at a frequency relative tothe temperature of the body tissues surrounding it. These data arethen transmitted harmlessly through the body to the monitor.

C O U R T E S Y O F C O R T E M P


31/152


How Do We Use Energy?One o he bes ways o esablish a concep is o provide muliple examples o he concepin acion. In his secion we presen a number o aciviies where sudens invesigaeenergy hrough chemical and physical reacions. Te aciviies presen chemical processesha will be amiliar o sudens hrough heir everyday lives, bu ocus on how energy isinvolved in he changes hey observe. Tese ideas are reinorced wih a chemical demon-

sraion, a video, and an aricle on he chemisry o explosives.Lab InvesigaionCombusion & BurningDemoSoda Can Seam EngineLab InvesigaionPreparaion & Combusion o BiodieselDemoElecrolysis o Waer

Videoemperaure & EnergyChemMaters ReadingTe Explosive Hisory o Nirogen


32/152


Combustion & Burning | A Lab Investigation

Summary

In his invesigaion, sudens are challenged o make careul observaions abou a burningcandle o discover he chemical and physical changes ha make i work.

Objective

Sudens will desribe heir observaions abou a burning candle o discover he chemical andphysical changes ha make i work.

Safety

Be sure o wear saey goggles while making close observaions, ie your hair back i youhave long hair, and always be aware o where he flame is wih respec o your clohingdo no lean over he flame.Burning candles are open flames ha can cause burns. Liquid wax is ho and can cause

burns o he skin.


ea ligh candleMachesSmall beaker or evaporaing dish (such as 50 mL or 100 mL)BalanceRuler or meer sickSring (or measuring circumerence)Sopwach

Time Required

One class period, approximaely 4550 minues.

Lab Tips

ea candles can be purchased in large quaniies, as can apered candles rom hardware sores.Candles o differen colors, sizes, and shapes can enrich he observaions made by he class.


Tis invesigaion could fi ino a uni on chemical reacions.


33/152



We are all amiliar wih burning candles, bu how much have we really seen while looking a one?In his exercise you will be challenged o observe a burning candle hrough he lens o chemisry.

You may be surprised by how much is really happening in wha seems like a amiliar process!

Firs we will ry o observe deails beyond our usual way o looking a a candle, and hen we willlook or evidence o he physical or chemical naure o any changes ha are aking place.ake care in recording your observaionsry o imagine ha you have never seen a burningcandle beore!

GATHERING EVIDENCE

Obain a ea ligh candle, maches, and any measuring equipmen available oyou. Beore lighing he candle, make hree qualiaive observaions and hree

quaniaive observaions o he candle.

Qualiaive observaions describe qualiies or characerisics, quaniaive obser-vaions involve quaniies, or measuremens. You may choose among manyproperies o observe: color, exure, mass, physical dimensions, densiy, aroma or any ohers

you can hink o. Use as many o your physical senses as possible, and be sure o include unis orany o your quaniaive observaions.

Record your observaions below:

Qualiaive observaions Quaniaive observaions

Use a mach o careully ligh he candle.

Repea he process o making qualiaive and quaniaive observaions o he burning candle,his ime making six o each kind o observaion. (Some o your observaions may relae o prop-eries you have already recorded, ha may be changing now ha he candle is burning.) Onceagain use all your senses o make qualiaive observaions. Ask yoursel wha you can measureor he quaniaive observaions.


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For your observaions and measuremens, consider no only he physical candle, bu also con-sider is influence on he air in he space surrounding i. Record your observaions below:


Now skech a deailed drawing o he burning candle, an enlargemen o he porion abou a cen-imeer rom he op o he candle o he opmos ip o he flame:

Label he ollowing regions o he candle in your drawing: solid wax, liquid wax, region o wickwihou flame, region o wick wih flame, and region o he wick ha glows.

Now disinguish as many differen aspecs o he flame isel and label hem in he drawing.When you have compleed recording your observaions and drawings, prepare o blow ou hecandle, and be ready o make urher observaions as you do his!


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Blow ou he candle and record wo qualiaive and wo quaniaive observaions o he candleimmediaely afer i is exinguished:


INTERPRETING EVIDENCE

Now ha we have paid close atenion o he properies o a burning candle, we can begin o

inerpre wha weve seen in erms o phase changes and chemical reacions.

In a phase change (rom solid o liquid or rom liquid o gas) he paricles o a subsance (in hiscase he molecules o wax) will change he arrangemen hey have wih each oher. As a solidhey will be closely packed ogeher and unable o move reely. In he liquid hey will be able oflow around each oher bu will sill be close ogeher, and as a gas hey will fly reely apar buhey will sill be wax molecules and will have he same srucure hey had as molecules in hesolid and he liquid phases:

In he boxes below, use small, single shapes o represen enire wax molecules, and skech heirarrangemen in he hree physical phases:

Waxes om plans and animals havedifferen srucures. Here is a moleculesimilar o wax, C

18H

38

a maerial

ha is normally a major componen ohe candle wax.


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Based on your observaions o he burning candle, did you find evidence or he change rom hesolid wax phase o he liquid wax phase?

C18

H38

(s) C18

H38

(l)

Describe his evidence as specifically as possible:

Did you find evidence or he change rom he liquid wax phase o he gaseous wax phase?

C18

H38

(l) C18

H38

(g)

Describe his evidence as specifically as possible:

A physical candle is composed o wax surrounding a wick. Look up he definiion o he verb owick, and wrie i below:

Solid Liquid Gas


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Describe he wicking process in he burning candle, and be sure your descripion includes hephysical sae o he wax and he wick:

As a candle burns, he wax gradually disappears rom sigh. Is here a physical change in he waxha would accoun or his disappearance?

I he wax was simply undergoing physical change, would you expec he candle o produce heaand ligh as i does when a candle burns?

Te process o burning (as opposed o evaporaing) is a chemical reacion, a chemical change.Te wax molecules are undergoing a chemical change; hey are changing ino differen molecules

by reacing wih a subsance in he air. Wha is his subsance in he air ha a candle needs oburn?

Ineresingly, a candle releases energy hrough he same kind o reacion ha your body uses oobain energy. Hold your breah or a momen. Wha is your body craving? Tis is he samesubsance he candle needs o burn in a chemical change ha we call combusion.

We can represen he combusion o a candle like his:

2 C18

H38

(s) + 55 O2 (g) 36 CO

2 + 38 H

2O

Complee he ollowing senence ha resaes his equaion:

wo molecules o wax reac wih ____________ molecules o oxygen o produce__________ molecules o _____________________________ and ___________

molecules o __________________.

We are no aware o oxygen in he air because i is an odorless and colorless gas, and a he em-peraure o a burning candle, boh he CO

2and he H

2O are also gases ha are invisible o us.

We can see evidence o chemical change, however, i we resric he amoun o oxygen ha isallowed o reac wih he wax.


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I less oxygen is available, one possible oucome in he combusion o wax is

2 C18

H38

(s) + 37 O2 (g) 18 C (s) + 18 CO

2 (g) + 38 H

2O (g)

Religh he candle and lower he botom o a small beaker or a clear wach glass ino he flameso ha he flame ouches he surace o he glass. Hold i here or a momen (where i resricssome o he air flow o he flame) and hen remove i.

Wha do you observe on he botom o he beaker? Wha could his subsance be and where didi come rom?

How does his provide evidence ha a chemical reacion is aking place?

Wipe he botom o he beaker clean and place an ice cube inside i. Hold he beaker several cen-imeers above (no in) he flame and allow he candle o burn. Can you see a subsance ormingon he botom o he beaker? Wha could his subsance be and where did i come rom? Couldi have come rom he meling ice inside he beaker?

Consider he flame isel. Is he flame a subsance produced by he candle? Wha observaionslead you o hink ha he flame is mater? In wha ways does he flame seem like energy?

Is he ollowing saemen rue or alse: As a candle burns, wax urns ino fire.

I his isn an accurae saemen, can you resae i correcly below?


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Finally, le us consider he physical phase o he wax as i reacs wih he oxygen o produce car-bon dioxide and waer. Prepare o observe careully! Blow ou he candle and very quickly bringa mach close o he wick. ry o noice exacly where he li wooden splin is wih respec o he

wick when he candle reignies.

Do his several imes o see i you observe somehing ineresing. Noe any evidence you haveobserved ha helps o deermine he physical phase o he wax when i reacs wih oxygen.

REFLECTING ON THE INVESTIGATION

Wha phase is he wax in when i mixes wih oxygen in he air and undergoes a chemical1.change?

Based on your observaions, in which phase (solid, liquid, or gas) is he wax mos likely o2.undergo a chemical change?

Explain why his is he case based on your skeches o wax in solid, liquid, and gas phases.3.

How migh his (your answer o quesion 3 above) explain a sign ha says NO SMOK-4.ING near he pumps a a gas saion?

Look back a your diagrams o he candle flame. Can you ideniy he region where he5.wick isel is undergoing combusion? Where is his region?

Wha is fire? Is i mater or is i energy? Explain your answer.6.

In a shor paragraph, summarize he changes ha a candle undergoes when i burns.7.Incorporae he ollowing words ino he paragraph in a meaningul way: wax, wick,phase change, chemical reacion, vaporize, mel, ransorms, solid, liquid, gas, energy,

ligh, and hea.


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Extension

Furher analysis problem using soichiomery:

Given he reacion ha we are using or he combusion o wax:

2 C18H38 (s) + 55 O2 (g) 36 CO2 + 38 H2O

Use soichiomery relaionships o calculae:

Te volume o oxygen gas needed a SP o burn 37.5 g o wax.1.

Te mass o carbon dioxide released when 37.5 g o wax burns.2.


2 C18H38 (s) + 37 O2 (g) 18 C (s) + 18 CO2 (g) + 38 H2O (g)

I his were o happen, wha mass o soo (carbon) is produced or every 1.0 g o wax ha burns?

Can you hink o anoher gas ha could be produced when here is insufficien oxygen oproduce CO

2?

Te ollowing links provide urher inquiry in differen aspecs o burning candles:

Tis sie rom NASA helps sudens gain insigh ino he characerisic shape o a candle flame by observing how a candle burns in zero graviy.htp://bi.ly/highschoolnrg3htp://bi.ly/highschoolnrg4

Diagrams and explanaions o candle combusion rom he Naional Candle Associaion:htp://bi.ly/highschoolnrg5

A Journal o Chemical Educaionaricle on observing candles ha includes a demonsra-

ion o he scorch marks lef on an index card held in a flame:htp://bi.ly/highschoolnrg6


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TEACHERS KEY

Reflecting on the Investigation

Wha phase (solid, liquid, or gas) is he wax in when i mixes wih oxygen in he air and1.undergoes a chemical change?

Gas

Based on your observaions, in which phase (solid, liquid, or gas) is he wax mos likely o2.undergo a chemical change?

In he gas phase surrounding he wick.

Explain why his is he case based on your skeches o wax in solid, liquid, and gas phases.3.

In he gaseous phase he wax molecules have more eedom o mix and collide wih oxygenmolecules in he air, and reac wih hem o produce waer and carbon dioxide.

How migh his (your answer o quesion 3 above) explain a sign ha says NO SMOK-4.ING near he pumps a a gas saion?

Gasoline ha has vaporized near he pumps may reac wih oxygen i exposed o an open flameor a li cigarete.

Look back a your diagrams o he candle flame. Can you ideniy he region where he5.wick isel is undergoing combusion? Where is his region?

A he very ip o he wick, where i is glowing orange, he wick isel is burning, or reacing wihoxygen in he air. Meled wax (in he process o changing ino gaseous wax) coas he res o hewick.

Wha is fire? Is i mater or is i energy? Explain your answer.6.

Boh. Wha we call fire is wha we see and eel when he gaseous reacans and producs o com-busion release energy in he orm o ligh and hermal energy ha heas he surroundings.


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Extension

Furher analysis problem using soichiomery:

Given he reacion ha we are using or he combusion o wax:

2 C18

H38

(s) + 55 O2 (g) 36 CO

2 + 38 H

2O

Use soichiomery relaionships o calculae:

Te volume o oxygen gas needed a SP o burn 37.5 g o wax.1.

90.8 L O2

Te mass o carbon dioxide released when 37.5 g o wax burns.2.117 g CO

2


2 C18

H38

(s) + 37 O2 (g) 18 C (s) + 18 CO

2 (g) + 38 H

2O (g)

I his were o happen, wha mass o soo (carbon) is produced or every 1.0 g o wax ha burns?

0.42 g C

Can you hink o anoher gas ha could be produced when here is insufficien oxygen oproduce CO

2?

CO


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Soda Can Steam Engine| A Demonstration

Summary

In his demonsraion, sudens consider he conceps o energy ransormaions and conserva-ion as hey observe a simple seam engine made rom an aluminum soda can.

Objective

Sudens learn abou energy ransormaions and he concep o conservaion o energy.

Safety

Be sure you and he sudens wear properly fiting goggles.Handle he ho soda can wih ongs. Seam rom he can could scald your hand and skin.

Materials

Unopened 12-oz aluminum soda can (using die soda will help avoid poenial sickiness)Tumback

Access o a sinkWash botleWaer10-mL graduaed cylinderSringRing sandRingBunsen burner or ho plaeongs

Time Required

Par o one class period, approximaely 1015 minues.


Tis demonsraion could fi ino a uni on phase changes, hermochemisry, or echnology.


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PREPARATION

Working over a sink, creae a hole in he middle o he side o an unopened soda can using1.a humback. Coninually shake he can, using he pressure generaed by carbonaion oorce he soda ou hrough he hole.

When he can is empy, creae a second hole on he side opposie he firs.2.

Rinse he can wih a wash botle, squiring waer ino one o he wo holes.3.

Once you have empied and rinsed he can, use he wash botle o add abou 10 mL waer4.(or enough so you hear i sloshing around inside he can).

Use he humback o slan each o he wo holes in he same direcion, angenial o he5.cans surace. Tese holes ac as jes in order o propel he can.

DEMONSTRATION

Shake he can so ha sudens can hear he waer sloshing around inside he can. Allow1.hem o observe ha he pull ab is unopened and ha here are wo holes in opposiesides o he can.

ie a sring o he cans unopened pull ab and secure he can o a ring atached o a ring2.sand a a heigh ha allows a Bunsen burner or ho plae o warm i.

While waiing or he can and waer o hea, ask sudens o predic wha will happen.3.

Genly warm he can and waer. Waer vapor will evenually exi boh holes and should4.resul in a ne orce ha ses he can spinning.

DISCUSSION WITH STUDENTSAsk sudens o describe any energy ransormaions presen in he demonsraion.1.

Challenge sudens o explain why he can behaves as i does. As long as he waer is2.heaed genly, no condensed waer vapor is visible as seam exis he can.

EXPLANATION

Energy may go hrough several conversions beore we acually use i o do work. Energy is noused up in any conversion; i is simply changed rom one orm o anoher. Like mater, he oalenergy is conserved.

Several energy conversions are involved in he demonsraion. Chemical energy rom he uelused in he Bunsen burner or he source ha produced he elecriciy (some possibiliies arehydroelecric, solar, wind, geohermal, nuclear, and peroleum energy sources) powering he hoplae is used o warm he waer and can. Some o he energy goes o overcoming he atracionsamong he liquid waer molecules so hey vaporize o produce warm waer vapor. Te molecules


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o he warm waer vapor have high kineic energy, which increases he pressure inside he canand hus orces some o he gas ou hrough he holes in he sides o he can. As hese jes o gasleave he can, hey push on he air ouside he can and creae an opposie push on he can, whichhen is parially convered o kineic energy as he escaping waer vapor causes he can o roae.Some o he energy rom he escaping waer vapor is also parially convered o poenial energyas he sring atached o he spinning can wiss.

EXTENSIONS

Insrucors may also wish o discuss he idea ha no energy conversion is 100% efficien in rans-orming one orm o energy o anoher desirable orm. Tus, some useul energy is always los

whenever energy is convered rom one orm o anoher. Te energy isel is no desroyed, bubecomes unavailable o do useul work. For example, some o he elecrical energy used in heoperaion o a hair dryer is convered o sound energy, which does no help o perorm he worko drying your hair.

Sudens can invesigae energy conversions in everyday iems. Some suggesions are ligh bulbs,bateries, oys, car engines, ec.

Sudens could research he early seam engine invened by Hero o Alexandria in he firs cen-ury A.D. and compare i o he soda can seam engine.

ADDITIONAL RESOURCE

Demonsraion Idea, Chemisry in he Communiy, 6h ed., eachers ed., New York: W. H.Freeman and Company/BFW, 2012, p 361.


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Preparation & Combustion of Biodiesel| A Lab Investigation

Summary

In his invesigaion, sudens use canola oil, ypically used in he kichen, o produce biodieselby reacing i wih mehanol using a poassium hydroxide caalys. Tey hen burn a sample o

he biodiesel produced. Te sample is placed underneah a soda can ha conains a measuredamoun o cold waer. Te iniial and final emperaures o he waer are recorded. Te colleceddaa is used o calculae he hea o combusion o he biodiesel, which is compared o he heo-reical hea o combusion o diesel uel rom crude oil. Te conceps o renewable and non-renewable uels are also discussed.

Objective

Sudens learn abou a reacion used o produce biodiesel, hea o combusion, and he concepso renewable and non-renewable uels.


25-mL graduaed cylinder10-mL graduaed cylinderCanola oil (25 mL)Mehanol (4 mL)Plasic conainer wih a screw-op lid (needs a capaciy o a leas 50 mL)Dropper9 M poassium hydroxide (KOH) (12.5 g KOH in 25-mL soluion)

Sodium chloride (0.5 g)Large es ube (needs a capaciy o a leas 3035 mL)Cork or sopper o seal large es ubees ube rack12-oz empy, clean aluminum sof drink can wih pull abRing sandRingTermomeerSirring rod

Maches Balanceea ligh candle wih meal cup and wick

Wach glass


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Safety

Be sure you and he sudens wear properly fiting goggles.

Burners mus no be used, since many reagens are flammable.

Mehanol paricularly poses a serious fire hazard, and is flame is almos invisible. Avoid

flames or sparks. Mehanol is also oxic by ingesion. Skin conac causes dermaiis.Work in a well-venilaed area.

When working wih alcohols such as mehanol, he Naional Science eachers Associa-ion recommends ha he primary reagen alcohol conainer be kep in he chemicalsoreroom. Te minimum quaniy o alcohol needed or he experimen should be avail-able o sudens:

htp://bi.ly/highschoolnrg7

Exreme cauion should be used wih 9 M KOH. I is causic and corrosive. Te insruc-or mus dispense drops o he concenraed base direcly ino each groups conainer.9 M poassium hydroxide is causic and corrosive. Avoid skin conac. In he even o skinor eye conac, rinse well wih waer. Have conac area evaluaed by qualified medicalpersonnel.

Insrucors should ollow heir own saes rules or proper disposal o wase. Te waselayer in he invesigaion conains mosly glycerol, excess mehanol, and poenially unre-aced poassium hydroxide. A useul documen is Biodiesel Saey and Bes ManagemenPracices or Small-Scale Noncommercial Use and Producion rom Penn Saes Collegeo Agriculural Sciences:

htp://bi.ly/highschoolnrg8

Time Required

wo class periods, approximaely 4550 minues each. Te biodiesel reacion mixure mus si

or a leas 30 minues or overnigh.

Pre-Lab Discussion

Tis invesigaion inroduces he concep o hea o combusion o a uel. I also highlighs hedifference beween renewable and non-renewable uel sources, in paricular, biodiesel and dieselobained rom crude oil. A discussion o he basic organic srucures presened in he invesiga-ion would be helpul.


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Lab Tips

Insead o shaking he botle wih he reacion mixure or 10 minues, a magneic sir bar appara-us could be used.

One opion or he plasic conainers wih screw-op lids are baby soda botles, also known as

soda botle preorms. Tese are sold by science supply companies and look like large plasic esubes wih 2-lier soda botle screw-op lids.

Te reacion mixure is ranserred o a es ube afer mixing so i is easier o see he wo layersseparaed and o decan he op biodiesel layer. Separaory unnels could be used insead i avail-able. Te ime needed or he invesigaion can be shorened i a cenriuge is available; porionso he reacion mixure can be cenriuged o obain he wo separaed layers raher han leavinghem o separae overnigh.

Chilled waer should be used in he combusion porion o he invesigaion. Ice can be added ocool he waer i needed. However, unmeled ice should be removed rom he waer beore usingi in he sof drink can.

Insrucors may wish o use only a ew 25-mL graduaed cylinders ha would be reserved or hisaciviy, as hey will become coaed wih oil and may be difficul o clean horoughly. Sudengroups can share he cylinders.


Tis invesigaion would fi ino unis on chemical reacions, hermodynamics, combusion, andgreen chemisry.


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How did you ge o school oday? Walk? Ride a bike? Cach a bus? Drive a car? Wha uel pow-ered your mehod o ransporaion? I you walked or biked, he uel migh have been a bowl o

breakas cereal. Many school buses use diesel uel, which is made rom crude oil ha was ormedover an incredibly long ime by he decomposiion o plans and animals. Wha i insead you

could fill your vehicles ank and run i wih recycled cooking oil? Sewage sludge? Pond scum? Isno as crazy as i may a firs sound.

Tese sources o a or plan oil are poenial saring maerials or biodiesel, a ype o renewableuel ha can be used in diesel engines. Renewable energy sou

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Energy Foundations