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Unit I: Matter & Energy
Textbook Chapters 1,2,11 & 12
What is Chemistry?Concerned with the properties of chemicals and the changes chemicals can undergo
Physical vs. Chemical Changes
• Physical Change change in appearance but the substance itself is not changed.
• Chemical Change produces new substances with different properties.
• Aka Chemical Reaction
Image taken from http://www.chem4kids.com/files/art/matter_intro_2_240.gif on 8/11/11.
H2O (l) H2O (s)
H2O + ½O2 H2O2
Paper Demo
Evidence of a Chemical Change/Reaction
1. Evolution of a Gas
2. Formation of a Precipitate
3. Release or Absorption of Energy
4. Color Change in the Reaction System
Image taken from http://toastyscience.edublogs.org/2011/02/02/1para-reactions-lab-1/ on 8/11/11.
Properties of Matter• Physical property
– Can be recognized without changing the substance to anything else.
– Examples: color, odor, density, melting pt.
• Chemical property– Describes how a substance reacts to form a
new substance.– Examples: stable, reactive, flammable, inert
Image taken from warningsignsdirect.co.uk on 8/11/11.
Common States (Phases) of Matter
• Solid
• Liquid
• Gas
• Plasma
Image taken from http://ds9.ssl.berkeley.edu/themis/mission_sunearth_closeup1.html on 8/11/11.
Solids• Particles close together• Particles vibrate but do not move• Strong attractive forces between particles• Crystalline structure (regular geometric pattern) • Definite shape• Definite volume• Lowest PE
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
Liquids
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
•Particles still close together.
•Particles vibrate and rotate allowing for movement.
•Weaker attractive forces between particles
•No regular pattern of particles
•Take shape of container
•Definite Volume
Gases
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
•Particles are very far apart and move all over.
•Particles vibrate, rotate and translate (move from place to place).
•Weakest attractive forces between particles.
•Take shape and volume of container.
•Greatest disorder
•Highest PE
Phase Changes• Types of Physical Change• Melting• Freezing (Solidification)• Vaporization (Boiling)• Condensation• Sublimation• Deposition
Image taken from http://www.splung.com/heat/images/phases/phasediagram.png on 8/11/11.
Sublimation of Iodine
{Change in Position of Particles (PE)}
•Triple point•At this temperature and pressure, substance can exist as a solid, liquid or gas.
•Under higher pressure, harder for a solid to melt or a liquid to boil.•Under lower pressure, melting and boiling points lower (easier to change).
Exception is water: increasing pressure, lowers freezing/melting point (think ice skating).
Endothermic vs. Exothermic• Endothermic
– Heat energy is absorbed.– Chemical Bonds broken in chemical rxn.
– 6 kcal + H2 + I2 2HI
• Exothermic– Excess heat is given off (released).– Chemical Bonds formed in chemical rxn.
– CaO(s) + H2O(l) Ca(OH)2(s) + 986 kJ/mol
Images taken from uline.com and en.wikipedia.org on 8/11/11.
Demo• Is this reaction exothermic or endothermic?
• Ba(OH)2.8H2O + 2NH4NO3+ 170kj/mol Ba(NO3)2 + 2NH3 + 10 H2O
Heating Curves• Endothermic or exothermic?
• Be able to label all phases, phase changes, changes in temperature, PE and KE.
Animated Heat Curve
Cooling Curves• Endothermic or
exothermic?
• Be able to label all phases, phase changes, changes in temperature, PE and KE.
2 Factors Affecting Phase of a Material
• Temperature
• Pressure
Image taken from http://invsee.asu.edu/srinivas/liquidmod/states.html on 8/11/11.
n.f.p.= solid-liquid equilibrium point
n.b.p.= liquid-gas equilibrium point
Vapor Pressure• Evaporation
• LG that takes place at the surface of the liquid and occurs at all temp’s.
• From evaporation, vaporization & boiling, the gas (vapor) produced exerts a pressure called vapor pressure.
• ↑Temp of liquid, ↑vapor pressure• Each substance has its own vapor pressure at
differing temperatures.• Ref Table H
Image taken from http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/imgkin/vapp2.gif on 8/11/11.
Vp animation
Boiling Point• Liquid will boil at temperature at which vapor
pressure = pressure on liquid.• Point of equilibrium between gas and liquid
• If vapor pressure = 1 atm (std pressure) then called the normal boiling point.
• Ref Table H
Image taken from http://images.tutorvista.com/content/solutions/manometer-vapour-pressure.jpeg on 8/11/11.
Low pressure lowers b.p. demo
7 Diatomics• Di = 2
• Atomic = atoms
• 7 elements that exist in nature as paired atoms in a molecule.
•To identify them, go to PT start with element #7 and make the shape of a #7 • N2,O2,F2,Cl2,Br2,I2
•Missing one? Whose #1?
• H2
Image taken from http://ths.talawanda.net/~BrambleN/classroom/Pictures/periodictablediatomic.JPG on 8/11/11.
Temperature vs. Heat• Which one has more heat, a pot of boiling water
or the Arctic Ocean?• Describe the temperature and heat of a 4th of
July sparkler.
SparklersSparklers
Temperature• Measure of the
average kinetic energy (KE) of the particles of a substance.
• Instrument• thermometer
• Units• Fahrenheit (o F)• Celsius (o C)• Kelvin (K) (SI Unit)
• Ref Table T
Image taken from http://www.visionlearning.com/library/module_viewer.php?mid=48 on 8/11/11.
Δ of 1oC= Δ of 1K
Temperature AnimationAnimated Temp Movie
Heat• Energy transferred
between objects that are at different temperatures.
• Energy always flows from source to sink.
• Instrument• calorimeter
• Units• Calories• Joules (SI Unit)
Image taken from http://www.g9toengineering.com/resources/heattransfer.jpg on 8/11/11.
Source ↑(Temp)
Sink ↓(Temp)
Specific Heat• Amount of heat energy required to raise the
temperature of 1 gram of a material 1oC
• What is the specific heat capacity of water?• Ref Table B
4.18 J/goC or 4.18 J/gK
• Equal to 1 calorie/goC
Image taken from http://media.web.britannica.com/eb-media/54/7054-004-8062DB49.gif on 8/11/11.
ESCI connection metals vs. water
Boiling water in a paper cup
Using a bomb calorimeter to determine calories of an almond (4min)
3 Heat Formulas (Ref Table T)
• Q=mHf
• Q=mHv
• Q=mcΔT
• Try examples!
• Ref Table B
Animated Heating CurveEm Cee Delta Tee video
Energy Conversion• Energy
– Ability to do work or transfer heat
• Law of Conservation of Energy
• Energy can not be created nor destroyed, just converted from one form to another.
• 2 Types of Energy• Kinetic and Potential
• Forms of Energy• Kinetic (motion, electrical,
sound, radiant, thermal)• Potential (chemical,
nuclear, gravitational, stored mechanical)
Image taken from http://www.ngdir.ir/sitelinks/kids/html/energy_mfahem_science_forms%20of%20energy.html.htm on 8/11/11.
Classifying Matter• Matter
– Anything that has mass and volume.
• Should remember terms mass, weight, volume and density (Ref Table T) from esci. [Text 1-2]
Image taken from http://www.meta-synthesis.com/webbook/31_matter/matter2.jpg on 8/11/11.
Elements• Substances that can not be broken down into
simpler substances by chemical means.• Each element is composed of one type of atom.
Examples:
Image taken from http://www.starkeith.net/coredump/wp-content/uploads//2008/06/the-elements.jpg on 8/11/11.
Review diatomics. allotropes
Compounds• 2 or more different elements chemically
combined in a definite ratio• Can be decomposed chemically into elements.
Image taken from http://wiki.district87.org/images/9/91/Compounds.jpg on 8/11/11.
Pure Substances• A sample of matter that has definite chemical
and physical properties.• All samples of a single pure substance are
identical in their properties.• Examples:
– elements & – compounds
Image taken from http://www.m2c3.com/chemistry/VLI/M1_Topic2/la_01_02.jpg on 8/11/11.
Mixtures• 2 or more substances physically combined with
no definite proportions.• In a mixture, each substance retains its own
properties.• Homogeneous or Heterogeneous
Image taken from http://www.m2c3.com/chemistry/VLI/M1_Topic2/la_01_02.jpg on 8/11/11.
Heterogeneous Mixtures• Physical combination of substances that are
NOT uniform in composition throughout.
• Examples: sand & water, tossed salad, milk
Milk under a microscope
Image taken from http://chestofbooks.com/reference/Facts-For-Everybody/images/Milk-474.png on 8/11/11.
Image taken from http://scienceprojectideasforkids.com/wp-content/uploads/2010/06/challenge-1-sep-mix-clue.jpg on 8/11/11.
Homogeneous Mixtures• Physical combination of substances that
are uniform in composition and properties throughout.
• Examples: salt & water, all solutions and alloys
Image taken from http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%20Exam%20Reviews/Exam%201%20Review/salt_in_solution.jpg on 8/11/11.
Separating Mixtures• Because mixtures are not chemically
combined, they can be separated physically.
• Such as….– Filtration– Centrifugation– Chromatography– Magnetism– Distillation Image taken from
http://library.thinkquest.org/11430/research/images/filtration.gif on 8/11/11.
Image taken from http://images.tutorvista.com/content/chemistry-concepts/magnetic-separation-process.jpeg on 8/11/11.
Distillation• Process by which a
mixture of liquids or a liquid and a solid can be separated by different boiling points.
Fractional Distillation of Petroleum
Distillation of Saltwater
Image taken from http://www.energyinst.org.uk/education/coryton/images/column.gif on 8/11/11.
Image taken from http://www.tutorvista.com/content/chemistry/chemistry-iii/organic-compounds/distillation.php on 8/11/11.
Image taken from http://wps.prenhall.com/wps/media/objects/165/169061/GIFS/AAAUASO0.JPG on 8/11/11.
Three Ways Compounds Differ from Mixtures
1. Compounds are chemically combined elements. Mixtures are physically combined substances.
2. Compounds are formed from a definite proportion. Mixtures can have varying proportions. (Compounds have a definite formula or “recipe”.
3. Compounds have different properties than ingredients. Mixtures retain the same properties of the ingredients.
Image taken from http://www.personal.kent.edu/~cearley/ChemWrld/Reaction/H2_O2.gif on 8/11/11.
NaCl (s)
NaCl (aq)
Molecular Models of Matter
Image taken from http://www.yenka.com/activities/Substances_and_Mixtures/attachments/Substances%20and%20Mixtures%20-%20Q2.gif on 8/11/11.
•Can you identify the following pics as …
•element, compound or mixture ???
•solid, liquid or gas???
More visualsOnline practice
Properties of Gases• Fluids
• Low Density
• Highly Compressible
• Completely Fill a ContainerPropane gas can be compressed in tanks for home heating and gas barbeques. It can be so highly compressed it becomes a liquid.
Pressure of Gases• Pressure
• Amount of force exerted per unit area of surface.
• Measured with barometer or manometer.• ex: atmospheric pressure• Units of pressure
– Atmospheres– Pascals– mm of Hg– Torr
Images taken from http://ths.talawanda.net/~BrambleN/classroom/Chemistry/Notes/Section%204A/PressureandTemperature.htm on 8/11/11.
Evangelista Torricelli1606-1647
How a barometer worksHow a manometer works
How Std. Atm. pressure is determined
Demo: pressure breaking stick Demo: Can Crush
STP• Use Reference Table A
• For Gases,• 273K = 0oC• 1atm = 29.92 inHg =
760mmHg = 760 torr = 101.3kPa
• For liquids and solids,• 25oC = ?K• Same pressure
Standard Temperature and Pressure
Image taken from http://www.free-online-private-pilot-ground-school.com/images/standard_sealevel_pressure.gif on 8/11/11.
Graham’s Law of Effusion (Diffusion)• Diffusion- spreading out from area of high to low
density.• Effusion-movement of gas through a small
opening into an evacuated chamber.• The rate of diffusion of a gas is inversely
proportional to the square root of the gas’s density.
Image taken from http://images.tutorvista.com/content/matter-states/diffusion-effusion-process.gif on 8/11/11.
Video
Kinetic Theory of Gasesor
Kinetic Molecular Theory (KMT)1. Gas-composed of individual particles which are
in continuous, random straight line motion2. Not all particles have same KE, avg KE of
particles=temp of gas3. Elastic collisions between particlestransfer of
energy w/ no loss(Total energy stays the same.)4. Volume of gas particles ignored compared to
volume of space in which they contain.5. Gas particlesno attraction to each other
Image taken from http://www.ucolick.org/~bolte/AY4_00/week6/gas_pressure.gif on 8/11/11.
Ideal Gases• Gases that follow the 5
points of KMT.• Best examples are gases
with small molecular masses like H2 and He.
• Low pressure and high temperature conditions are the best for ideal gases.
Image taken from www.wix.com on 8/11/11.
Real Gases deviate from KMT.• Especially under High pressure and Low
temperatures.
• Can you think of ways gases would deviate (not follow) from KMT?
KMT
Image taken from http://library.thinkquest.org/C006669/media/Chem/img/PV.gif on 8/11/11.
Gas Laws• Boyle’s
• Charles’
• Gay-Lussac
• Combined
• Ideal
Boyles’ Law• At constant temp., volume of a
given mass of gas varies inversely with pressure
• PV=K or V1/V2 = P2/P1
• Example: Robert Boyle (1627-91)
Image taken from http://en.wikipedia.org/wiki/Robert_Boyle on 8/11/11.
Animation
Animation 2 w/ graphing
Charles’ Law• At constant pressure, the volume
of a given mass of gas varies directly with Kelvin temperature.
• V1/V2=T1/T2 or V/T=k
• Example:
Animation
Balloon Demo
Jacques Charles (1746-1823)
Image taken from http://www.scientificamerican.com/article.cfm?id=what-is-charles-lawon 8/11/11.
V
Gay-Lussac• At constant volume, the Kelvin
temperature of a gas is directly related to the pressure.
• P1/T1 = P2/T2
• Example:
Joseph Gay-Lussac (1778-1850)
Image taken from http://www.greatscientists.net/cms/wp-content/uploads/joseph-louis-gay-lussac.jpg on 8/11/11.
Animation
Pressure Cooker
Image taken from toolskitchen.net on 8/11/11.
Combined Gas Law• Changes in volume, pressure and
temperature of a gas often occur simultaneously.
• Combine Boyle’s, Charles’ & Gay-Lussac’s.• Formula on Ref Table T, remember K temp.• Example:
Narrated Animation of all Gas Laws
Examplesa) A sample of 150.0 mL of oxygen gas is under
760.0 mmHg of pressure. What will be the new volume of O2(g) if the pressure is reduced to 750.0 mmHg?
b) A 250.0 mL Helium balloon is at a temperature of -23.0oC. What is the size of the balloon going to be if the system is warmed to 7.00oC?
c) A 175mL sample of gas is at 20.0oC and 1.00 atm. What will the new volume be if the temperature is lowered to 10.0oC and the pressure is raised to 1.50 atm?
Partial Pressures• Pressure exerted by each of the
gases in a gas mixture.• Total P = sum of partial pressures
Image taken from http://apollo.lsc.vsc.edu/classes/met130/notes/chapter4/graphics/parcel2.free.gif on 8/11/11.
Image taken from http://reich-chemistry.wikispaces.com/file/view/P3.JPG on 8/11/11.
solve?solve?
John Dalton (1766-1844)
Image taken from http://www.chemistryexplained.com/images/chfa_02_img0256.jpg on 8/11/11.
Avogadro’s Hypothesis• Equal volumes of gases under the
same conditions of temp. & pressure contain equal numbers of particles.
• Avogadro’s #=1 mole=6.02 X1023
Amedeo Avogadro (1776-1856)
Image taken from http://en.wikipedia.org/wiki/Amedeo_Avogadro on 8/11/11.
Image taken from http://library.thinkquest.org/12596/bonus_avogadro.gif on 8/11/11.
Ideal Gas Law• Includes the number of moles of gas
related to P (atm. or kPa), T (K) &V (L).
• Derived from KMT.
• PV=nRT• Which variables are directly related? Inversely related?
• Example:
n= number of moles of gas
R is the gas constant
R=0.0821 L.atm/mol.K
a) At 5.00 atmospheres pressure and 70.0oC, how many moles are present in 1.50 liters of O2 gas?
R=8.314 L.kPa/mol.K
b) How many moles of gas are contained in 22.41 liters at 101.325 kPa and 0.00oC?