Matter and Energy Chapter 3

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Matter and Energy

Chapter 3

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Properties

• Characteristics of the substance under observation

• Properties can be either directly observable orthe manner something interacts with other

substances in the universe

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Universe Classified

• Matter is the part of the universe that has mass and volume

• Energy is the part of the universe that has the ability to do work

• Chemistry is the study of matter– The properties of different types of matter– The way matter behaves when influenced

by other matter and/or energy

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Properties of Matter• 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

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Classify Each of the following as Physical or Chemical Properties

The boiling point of ethyl alcohol is 78°C.

Diamond is very hard.

Sugar ferments to form ethyl alcohol.

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Classify Each of the following as Physical or Chemical Properties

The boiling point of ethyl alcohol is 78°C.– Physical property – describes inherent characteristic

of alcohol – boiling pointDiamond is very hard.

– Physical property – describes inherent characteristic of diamond – hardness

Sugar ferments to form ethyl alcohol.– Chemical property – describes behavior of sugar –

forming a new substance (ethyl alcohol)

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• solid, liquid, gas

States of Matter

State Shape Volume Compress FlowSolid Keeps

ShapeKeepsVolume

No No

Liquid TakesShape ofContainer

KeepsVolume

No Yes

Gas TakesShape ofContainer

TakesVolume ofContainer

Yes Yes

Liquid water takes the shape of its container.

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Changes in Matter

• Physical Changes are changes to matter that do not result in a change the fundamental components that make that substance– State Changes – boiling, melting, condensing

• Chemical Changes involve a change in the fundamental components of the substance– Produce a new substance– Chemical reaction– Reactants Products

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Classify Each of the following as Physical or Chemical Changes

Iron metal is melted.

Iron combines with oxygen to form rust.

Sugar ferments to form ethyl alcohol.

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Classify Each of the following as Physical or Chemical Changes

Iron is melted.– Physical change – describes a state change, but the

material is still ironIron combines with oxygen to form rust..

– Chemical change – describes how iron and oxygen react to make a new substance, rust

Sugar ferments to form ethyl alcohol.– Chemical change – describes how sugar forms a new

substance (ethyl alcohol)

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Elements and Compounds

• Substances which can not be broken down into simpler substances by chemical reactions are called elements

• Most substances are chemical combinations of elements. These are called compounds.– Compounds are made of elements– Compounds can be broken down into elements– Properties of the compound not related to the

properties of the elements that compose it– Same chemical composition at all times

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Classification of Matter

• Homogeneous = uniform throughout, appears to be one thing– pure substances– solutions (homogeneous mixtures)

• Heterogeneous = non-uniform, contains regions with different properties than other regions

P u re S ub s ta n ceC o n s tan t C o m p o s it ion

H o m o ge n e o us

M ix tu reV a ria b le C o m p o s ition

M a tte r

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Pure Substances vs. Mixtures• Pure Substances

– All samples have the same physical and chemical properties– Constant Composition all samples have the same

composition– Homogeneous– Separate into components based on chemical properties

• Mixtures– Different samples may show different properties– Variable composition– Homogeneous or Heterogeneous– Separate into components based on physical properties

• All mixtures are made of pure substances

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Identity Each of the following as a Pure Substance, Homogeneous

Mixture or Heterogeneous Mixture

Gasoline

A stream with gravel on the bottom

Copper metal

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Identity Each of the following as a Pure Substance, Homogeneous

Mixture or Heterogeneous Mixture

Gasoline – a homogenous mixture

A stream with gravel on the bottom– a heterogeneous mixture

Copper metal– A pure substance (all elements are pure substances)

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Separation of Mixtures• Separate mixtures based on different physical

properties of the components– Physical change

EvaporationVolatility

ChromatographyAdherence to a Surface

FiltrationState of Matter (solid/liquid/gas)

DistillationBoiling Point

TechniqueDifferent Physical Property

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Energy and Energy Changes

• Capacity to do work– chemical, mechanical, thermal,

electrical, radiant, sound, nuclear• Energy may affect matter

– e.g. raise its temperature, eventually causing a state change

– All physical changes and chemical changes involve energy changes

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Heat• Heat: a flow of energy due to a temperature

difference

1. Exothermic = A process that results in the evolution of heat.• Example: when a match is struck, it is an

exothermic process because energy is produced as heat.

2. Endothermic = A process that absorbs energy.• Example: melting ice to form liquid water is an

endothermic process.

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Units of Energy

• One calorie is the amount of energy needed to raise the temperature of one gram of water by 1°C– kcal = energy needed to raise the temperature of 1000 g

of water 1°C• joule

– 4.184 J = 1 cal• In nutrition, calories are capitalized

– 1 Cal = 1 kcal

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Example - Converting Calories to Joules

251Jcal 1

J 4.184 60.1cal

joules 4.184 cal 1

Convert 60.1 cal to joules

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Energy and the Temperature of Matter

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

temperature will increase twice as much.• The amount the temperature of an object

increases depends 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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Specific Heat Capacity• Specific Heat (s) is the amount of energy

required to raise the temperature of one gram of a substance by one Celsius degree

C gJ 4.184 is water ofheat specific the,definitionBy

Amount of Heat = Specific Heat x Mass x Temperature ChangeQ = s x m x T

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Example – Calculate the amount of heat energy (in joules) needed to raise

the temperature of 7.40 g of water from 29.0°C to 46.0°C

Mass = 7.40 g

Temperature Change = 46.0°C – 29.0°C = 17.0°C

J 526 C17.07.40gC g

J 4.184 Heat

Specific Heat of Water = 4.184 C-g

JC g

J

Q = s x m x T

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Example – A 1.6 g sample of metal that appears to be gold requires 5.8 J to raise

the temperature from 23°C to 41°C. Is the metal pure gold?

C gJ0.20

C18x g 1.6J 5.8 s

C18 C23 - C41 TT m

Q s

Tms Q

Table 3.2 lists the specific heat of gold as 0.13Therefore the metal cannot be pure gold.