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Chapter 6Energy and States of Matter

States of Matter

Melting and Freezing

Boiling and Condensation

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States of Matter

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What are the three states of matter?

solid liquid gas

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Solids

Definite shape

Definite volume

Particles close together, fixed

Particles move very slowly

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Liquids

Indefinite shape, definite volume

Take the shape of container

Particles are close together, but mobile

Particles move slowly

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Gases

Indefinite shape

Indefinite volume

Take the shape and volume of container

Particles are far apart

Particles move fast

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Learning Check S1

Match: (1) solid, (2) liquid, or (3) gas.

____ A. Has a definite volume, but shape of the container.

____ B. Its particles are moving rapidly.

____ C. Fills the volume of a container.

____ D. Particles are in a fixed structure.

____ E. Particles are close together, but mobile.

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Solution S1

Match: (1) solid, (2) liquid, or (3) gas.

_2_ A. Has a definite volume, but shape of the container.

_3_ B. Its particles are moving rapidly.

_3_ C. Fills the volume of a container.

_1_ D. Particles are in a fixed structure.

_2_ E. Particles are close together, but mobile.

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Heat Calculation for Fusion

Heat = g water x 80. J g water

How much heat in calories is needed to melt 15.0 g of water?

15.0 g water x 80. cal = 1200 cal

1 g water

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Changes of State

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Learning Check CS2

A. Why does the temperature of ice

stay at 0°C while the ice melts?

B. How much heat in joules is needed to melt 1.00 g of ice of 0°C?

1) 1.00 J 2) 100 J 3) 334 J

C. How many joules of heat are released when 100.0 g of water at 0°C freezes (0°C)?

1) 3.34 J 2) 3340 J 3) 33,400 J

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Solution CS2

A. Why does the temperature of ice

stay at 0°C while the ice melts? Energy goes into the change of state.

B. How much heat in joules is needed to melt 1.00 g of ice of 0°C?

3) 334 J

C. How many joules of heat are released when 100.0 g of water at 0°C freezes (0°C)?

3) 33,400 J

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Heat of Vaporization

Amount of heat needed to change 1 gram of liquid to gas at its boiling point

Boiling (Condensing) Point of Water = 100°C

Heat of Vaporization (water) = 2260 J/g

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Learning Check CS3

Water boils at 100°C when a low flame is used. Why does it still boil at 100°C when a high flame is used?

Why is water sprayed on orange trees when the temperature is going to drop to freezing?

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Solution CS3

Water boils at 100°C when a low flame is used. Why does it still boil at 100°C when a high flame is used?

At 100°C liquid molecules acquire the energy needed to break away from the liquid as gas molecules

Why is water sprayed on orange trees when the temperature is going to drop to freezing?

Freezing is exothermic. Heat is released and keeps the temperature around the trees above freezing.

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Learning Check CS4

A. Ice cubes in a warm drink will

1) melt 2) freeze 3) not change

B. The liquid drink _________ energy.

1) loses 2) gains 3) does not change

C. The ice ___________energy.

1) loses 2) gains 3) does not change

D. The final temperature of the ice and liquid is

1) the same 2) different

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Solution CS4

A. Ice cubes in a warm drink will 1) melt

B. The liquid drink 1) loses energy.

C. The ice 2) gains energy.

D. The final temperature of the ice and liquid is 1) the same