Introductory Chemistry , 3 rd Edition Nivaldo Tro

Roy KennedyMassachusetts Bay Community College

Wellesley Hills, MA

Introductory Chemistry, 3rd EditionNivaldo Tro

Chapter 3Matter and Energy

2009, Prentice Hall

Are matter & energy related• Matter is any particle with mass and volume

• Energy is simply matter that is moving

• 0 Kelvin is defined as the temperature when matter does not moving

• So temperature is related to moving mass

• Or temperature and mass are related to energy of particles

• That’s why any chemistry or physics equation with energy must relate mass and temperature.

Tro's "Introductory Chemistry", Chapter 3

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Around you

• Everything you can see, touch, smell or taste in your room is made of matter.


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What Is Matter?• Matter is anything with

mass.• Typically, we think of tiny

little pieces of mass as atoms and molecules because those 117 elements behave Newtonian. There are over 200 smaller particles that behave Quantunian.

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Energy: it’s just Mass and Velocity• Electrical

Kinetic energy associated with the flow of electrical charge.

• Heat or Thermal EnergyKinetic energy associated with molecular motion.

• Light or Radiant EnergyKinetic energy associated with energy transitions in an atom.

• NuclearPotential energy in the nucleus of atoms.

• ChemicalPotential energy in the attachment of atoms or because of their

position.


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Atoms and Molecules

• Atoms are the tiny particles that make up all matter.

• In most substances, the atoms are joined together in units called molecules.The atoms are joined in

specific geometric arrangements.

Any matter can exist in one of 3 States

• Solid

• Liquid

• Gas


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Structure Determines Properties• The atoms or molecules have different

structures in solids, liquids, and gases − leading to different properties.


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Solids• The particles in a solid are packed

close together and are fixed in position.Although they may vibrate.

• The close packing of the particles results in solids being incompressible.

• The inability of the particles to move around results in solids retaining their shape and volume when placed in a new container and prevents the particles from flowing.


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Solids, Continued• Some solids have their particles

arranged in an orderly geometric pattern—we call these crystalline solids.Salt and diamonds.

• Other solids have particles that do not show a regular geometric pattern over a long range—we call these amorphous solids.Plastic and glass.


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Liquids• The particles in a liquid are closely packed,

but they have some ability to move around. • The close packing results in liquids being

incompressible.• The ability of the particles to move allows

liquids to take the shape of their container and to flow. However, they don’t have enough freedom to escape and expand to fill the container.


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Gases

• In the gas state, the particles have complete freedom from each other.

• The particles are constantly flying around, bumping into each other and the container.

• In the gas state, there is a lot of empty space between the particles.On average.


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Gases, Continued• Because there is a lot of empty

space, the particles can be squeezed closer together. Therefore, gases are compressible.

• Because the particles are not held in close contact and are moving freely, gases expand to fill and take the shape of their container, and will flow.


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Matter: is it pure or impure

• Pure Substance = All samples are made of the same pieces in the same percentages. Salt

• Mixtures = Different samples may have the same pieces in different percentages. Salt water

Pure SubstanceConstant Composition

Homogeneous

MixtureVariable Composition

Matter

Heterogeneous


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Mixtures

1. Made of multiple substances, but appears to be one substance.

2. All portions of a sample have the same composition and properties.

1. Made of multiple substances, whose presence can be seen.

2. Portions of a sample have different composition and properties.

Heterogeneous Homogeneous

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Matter Summary


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Matter has Properties• Physical Properties are the characteristics of matter

that can be changed without changing its composition.Characteristics that are directly observable.

• Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy. Characteristics that describe the behavior of matter.

Chapter One 19

H2O Physical verses H2O Chemical


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Physical Properties

Melting Point Boiling Point

Electrical Conductivity

Thermal Conductivity

Magnetism

Malleability Ductility Specific Heat

Color Order Taste

Solid Liquid Gas


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Some Physical Properties of Iron• Iron is a silvery solid at room temperature with a metallic taste

and smooth texture.• Iron melts at 1538 °C and boils at 4428 °C.• Iron’s density is 7.87 g/cm3.• Iron can be magnetized.• Iron conducts electricity, but not as well as most other common

metals.• Iron’s ductility and thermal conductivity are about average for a

metal.• It requires 0.45 J of heat energy to raise the temperature of one

gram of iron by 1°C.


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Chemical Properties

Acidity Basicity

Inertness Explosiveness

Inflammable Flammable

Oxidizing Reducing


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Some Chemical Properties of Iron

• Iron is easily oxidized in moist air to form rust.

• When iron is added to hydrochloric acid, it produces a solution of ferric chloride and hydrogen gas.

• Iron is more reactive than silver, but less reactive than magnesium.

Quiz: is it a Physical or Chemical Property

• Salt is a white, granular solid = physical.• Salt melts at 801 °C = physical.• Salt is stable at room temperature, it does not decompose

= chemical.• 36 g of salt will dissolve in 100 g of water = physical.• When a clear, colorless solution of silver nitrate is added

to a salt solution, a white solid forms = chemical.


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Matter has Properties, Matter can also go through Changes

• Changes that alter the state or appearance of the matter without altering the composition are called physical changes.

• Changes that alter the composition of the matter are called chemical changes.

During the chemical change, the atoms that are present rearrange into new molecules, but all of the original atoms are still present.


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Is it a Physical or Chemical Change?• A physical change results in a different form of

the same substance.The kinds of molecules don’t change.

• A chemical change results in one or more completely new substances.Also called chemical reactions.

The new substances have different molecules than the original substances.

You will observe different physical properties because the new substances have their own physical properties.


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Phase Changes ArePhysical Changes

• Boiling = liquid to gas.• Melting = solid to liquid.• Subliming = solid to gas.• Freezing = liquid to solid.• Condensing = gas to liquid.• Deposition = gas to solid.• State changes require heating or cooling the substance.

Evaporation is not a simple phase change, it is a solution process.

• Evaporation of rubbing alcohol = physical.• Sugar turning black when heated = chemical.• An egg splitting open and spilling out =

physical.• Sugar fermenting into alcohol = chemical.• Bubbles escaping from soda = physical. • Bubbles that form when hydrogen peroxide is

mixed with blood = chemical.Tro's "Introductory Chemistry",

Chapter 328

Quiz: is it a Physical or Chemical change


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Separation of Mixtures• Separate mixtures based on different

physical properties of the components.Physical change.

Centrifugation and

decanting

Density

EvaporationVolatility

ChromatographyAdherence to a surface

FiltrationState of matter (solid/liquid/gas)

DistillationBoiling point

TechniqueDifferent Physical Property


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Distillation: different boiling points

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Filtration: different solubility's

Summary• Moving Matter has Energy. Motion is

related to temperature. All energy formulas are relations between mass and temperature

• Matter has 3 states

• Matter has properties

• Matter can change


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States/Properties/Changeare all related to temperatureand how much you have


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Law of Conservation of Mass• Antoine Lavoisier

• “Matter is neither created nor destroyed in a chemical reaction.”

• The total amount of matter present before a chemical reaction is always the same as the total amount after.

• butane + oxygen carbon dioxide + water 58 grams + 208 grams 176 grams + 90 grams

266 grams = 266 grams


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Law of Conservation of Energy

• “Energy can neither be created nor destroyed.”

• The total amount of energy in the universe is constant. There is no process that can increase or decrease that amount.

• Note: neither Mass nor Energy are ever destroyed


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Energy• The Fundamental Principle of the Universe is

Energy• From the Greeks to Newton to Quantum

Mechanics Energy is known as the capacity to do work and is simply calculated by knowing the mass and velocity of a particle.

• The harder you swing an ax the faster you can fall a tree.

• Guess what happens when you walk into a wall .005 mph or 500 mph

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Energy: it’s just Mass and Velocity• Electrical

Kinetic energy associated with the flow of electrical charge.

• Heat or Thermal EnergyKinetic energy associated with molecular motion.

• Light or Radiant EnergyKinetic energy associated with energy transitions in an atom.

• NuclearPotential energy in the nucleus of atoms.

• ChemicalPotential energy in the attachment of atoms or because of their

position.

• You take slow moving particles and make them move faster

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To get Energy (electrical, thermal, light, nuclear, chemical)

As slow moving water falls, gravity pulls it faster. The water falls on top of a turbine, which moves a coil in a magnet to generate electricity.


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Binding energy is simply the amount of energy (and mass) released, when free nucleonsjoin to form a nucleus; a gluon is released or absorbedEinstein's mass-energy equivalence formula E = mc² can be used to compute the binding energy


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Kinds of EnergyKinetic and Potential

• Potential energy is energy that is stored; slow moving Water flows because gravity pulls it

downstream. However, the dam won’t allow it to

move, so it has to store that energy.• Kinetic energy is energy of motion,

or energy that is being transferred from one object to another; fast moving. When the water flows over the dam,

some of its potential energy is converted to kinetic energy of motion.


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There’s No Such Thing as a Free Ride

When atoms contact each other, frictions is produced. You will often notice friction as sound or heat. So instead of useful energy, “anti-energy” friction slows your car down.


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Units of Energy

• Calorie (cal) is the amount of energy needed to raise one gram of water by 1 °C.kcal = energy needed to raise 1000 g of water 1 °C.food calories = kcals.

Energy Conversion Factors

1 calorie (cal) = 4.184 joules (J)

1 Calorie (Cal) = 1000 calories (cal)

1 kilowatt-hour (kWh) = 3.60 x 106 joules (J)


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Energy Use 2008

Unit

Energy Required to Raise Temperature of 1 g of Water by 1°C

Energy Required to Light 100-W Bulb for 1 Hour

Energy Used by Average U.S. Citizen in 1 Day

joule (J) 4.18 3.6 x 105 9.0 x 108

calorie (cal) 1.00 8.60 x 104 2.2 x 108

Calorie (Cal) 1.00 x 10-3 86.0 2.2 x 105

kWh 1.1 x 10-6 0.100 2.50 x 102

Example 3.5—Convert 225 Cal to Joules

Units and magnitude are correct.

Check:7. Check.

225 Cal = 9.41 x 105 JRound:6. Significant figures and round.

Solution:5. Follow the solution map to Solve the problem.

Solution Map:

4. Write a Solution Map.

1 Cal = 1000 cal1 cal = 4.184 J

Conversion Factors:

3. Write down the appropriate Conversion Factors.

? JFind:2. Write down the quantity you want to Find and unit.

225 CalGiven:1. Write down the Given quantity and its unit.

Cal

cal 1

J .1844

J 1041.9cal 1

J .1844

Cal 1

cal 1000Cal 252 5

cal J

Cal 1

cal 1000

3 sig figs

3 significant figures


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Chemical Potential Energy• The amount of energy stored in a material is its

chemical potential energy.• The stored energy arises mainly from

the attachments between atoms in the molecules the attractive forces between molecules.


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Exothermic Processes

• When a change results in the release of energy it is called an exothermic process.

• An exothermic chemical reaction occurs when the reactants have more chemical potential energy than the products.

• The excess energy is released into the surrounding materials, adding energy to them.Often the surrounding materials get hotter from the

energy released by the reaction.


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An Exothermic Reaction

Pot

enti

al e

nerg

y

Reactants

Products

Surroundings

reaction

Amount of energy released


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Endothermic Processes

• When a change requires the absorption of energy it is called an endothermic process.

• An endothermic chemical reaction occurs when the products have more chemical potential energy than the reactants.

• The required energy is absorbed from the surrounding materials, taking energy from them.Often the surrounding materials get colder due to the

energy being removed by the reaction.


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An Endothermic Reaction

Pot

enti

al e

nerg

y

Products

Reactants

Surroundings

reaction

Amount of energy absorbed

Temperature Scales

Celsius Kelvin Fahrenheit-273°C-269°C

-183°C

-38.9°C

0°C

100°C

0 K4 K

90 K

234.1 K

273 K

373 K

-459 °F-452°F

-297°F

-38°F

32°F

212°F

Absolute zero

BP helium

Boiling point oxygen

Boiling point mercury

Melting point ice

Boiling point water

0 R7 R

162 R

421 R

459 R

671 R

Rankine

Room temp25°C 298 K 75°F 534 R


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Fahrenheit vs. Celsius

• A Celsius degree is 1.8 times larger than a Fahrenheit degree.

• The standard used for 0° on the Fahrenheit scale is a lower temperature than the standard used for 0° on the Celsius scale.

1.8

32-F C


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The Kelvin Temperature Scale• Both the Celsius and Fahrenheit scales have

negative numbers.Yet, real physical things are always positive amounts!

• The Kelvin scale is an absolute scale, meaning it measures the actual temperature of an object.

• 0 K is called absolute zero, all molecular motion stops.0 K = -273 °C = -459 °F.Absolute zero is a theoretical value obtained by

following patterns mathematically.


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Kelvin vs. Celsius• The size of a “degree” on the Kelvin scale is the

same as on the Celsius scale.Although technically, we don’t call the divisions on the

Kelvin scale degrees; we call them kelvins!That makes 1 K 1.8 times larger than 1 °F.

• The 0 standard on the Kelvin scale is a much lower temperature than on the Celsius scale.

• When converting between kelvins and °C, remember that the kelvin temperature is always the larger number and always positive!

273C K

Example 3.7—Convert –25 °C to Kelvins


Check:7. Check.

258 KRound:6. Significant figures and round.


Solution Map:


Equation:3. Write down the appropriate Equations.

KFind:2. Write down the quantity you want to Find and unit.

-25 °CGiven:1. Write down the Given quantity and its unit. units place

units place

° C K

273C K

K 258273C) 25(K

K = ° C + 273

Example 3.8—Convert 55° F to Celsius


Check:7. Check.

12.778 °C = 13 °CRound:6. Significant figures and round.


Solution Map:



° CFind:2. Write down the quantity you want to Find and unit.

55 °FGiven:1. Write down the Given quantity and its unit.

units placeand 2 sig figs

units place and 2 sig figs

° F ° C

1.8

32-F C

1.8

32-F C

C 778.12

1.8

32-F 55 C

Example 3.9—Convert 310 K to Fahrenheit


Check:7. Check.

98.6 °F = 99 °FRound:6. Significant figures and round.


Solution Map:



°FFind:2. Write down the quantity you want to Find and unit.

310 KGiven:1. Write down the Given quantity and its unit.

units placeand 3 sig figs

units place and 2 sig figs

1.8

32-F C

32C1.8 F

F 6.9832C 37.81 F

K = °C + 273

°F°CK

°C = K - 273

C 37273310 C


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Practice—Convert 0 °F into Kelvin


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Practice—Convert 0 °F into Kelvin, Continued

°C = 0.556(°F-32)°C = 0.556(0-32)

°C = -18 °C

K = °C + 273K = (-18) + 273

K = 255 K


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Energy and the Temperature of Matter

• The amount the temperature of an object increases depends on the amount of heat energy added (q).If you double the added heat energy the

temperature will increase twice as much.

• The amount the temperature of an object increases depending on its mass.If you double the mass, it will take twice as

much heat energy to raise the temperature the same amount.

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Heat Capacity• Heat capacity is the amount of heat a substance

must absorb to raise its temperature by 1 °C.cal/°C or J/°C.Metals have low heat capacities; insulators have

high heat capacities.• Specific heat = heat capacity of 1 gram of the

substance.cal/g°C or J/g°C.Water’s specific heat = 4.184 J/g°C for liquid.

Or 1.000 cal/g°C.It is less for ice and steam.


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Specific Heat Capacity• Specific heat is the amount of energy required to raise the

temperature of one gram of a substance by 1 °C. • The larger a material’s specific heat is, the more energy it

takes to raise its temperature a given amount.• Like density, specific heat is a property of the type of

matter. It doesn’t matter how much material you have. It can be used to identify the type of matter.

• Water’s high specific heat is the reason it is such a good cooling agent. It absorbs a lot of heat for a relatively small mass.


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Specific Heat CapacitiesSubstance Specific Heat

J/g°C Aluminum 0.903

Carbon (dia) 0.508

Carbon (gra) 0.708

Copper 0.385

Gold 0.128

Iron 0.449

Lead 0.128

Silver 0.235

Ethanol 2.42

Water (l) 4.184

Water (s) 2.03

Water (g) 2.02


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Heat Gain or Loss by an Object

• The amount of heat energy gained or lost by an object depends on 3 factors: how much material there is, what the material is, and how much the temperature changed.

Amount of Heat = Mass x Heat Capacity x Temperature Change

q = m x C x T

J 557.4

C25.0-29.9 0.372g 2.5 Cg

J

q

q

Example 3.10—Calculate Amount of Heat Needed to Raise Temperature of 2.5 g Ga from 25.0 to 29.9 °C


Check:7. Check.

4.557 J = 4.6 JRound:6. Significant figures and round.


Solution Map:



q, JFind:2. Write down the quantity you want to Find and unit.

m = 2.5 g, T1 = 25.0 °C, T2= 29.9 °C, C = 0.372 J/g°C

Given:1. Write down the Given quantity and its unit.

2 significant figures

m, C, T q

TCmq

TCmq


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Practice—Calculate the Amount of Heat Released When 7.40 g of Water Cools from 49° to 29 °C

Practice—Calculate the Amount of Heat Released When 7.40 g of Water Cools from 49° to 29 °C,

Continued

q = m ∙ Cs ∙ T

Cs = 4.18 J/gC (Table 3.4)

The unit and sign are correct.

T1 = 49 °C, T2 = 29 °C, m = 7.40 g

q, J

Check:• Check.

Solution:• Follow the concept plan to solve the problem.

Solution Map:

Relationships:

• Strategize

Given:

Find:

• Sort Information

TC mq s Δ

J 106.2J 64.816

C 02- 4.18g 7.40

Δ

2

CgJ

TCmq s

C 02-

C94 - C 29

12

T

TTT

Cs m, T q

Documents

Introductory Chemistry , 3 rd Edition Nivaldo Tro