Chapter 8 - States of Matter

Question 1

What is an endothermic change?

Answer 1

A change of state in which the substance gains energy as it changes state.

Question 2

What is an exothermic change?

Answer 2

A change of state in which the energy is removed from the substance as it changes state.

Question 3

What are some examples of an exothermic change?

Answer 3

1. Freezing

2. Condensation

Question 4

What are some examples of an endothermic change? (3 Things)

Answer 4

1. Melting
2. Evaporation
3. Sublimation

Question 5

What is sublimation?

Answer 5

A change of state in which a substance’s particles go from a solid (particles are moving slowly, being very close together, having a lot of attraction between them) to a gas (particles have no attraction between them, move very quickly, and move independently) very quickly

Question 6

Describe a solid in terms of shape and volume.

Answer 6

Shape: Definite
Volume: Definite

Question 7

Describe a liquid in terms of shape and volume.

Answer 7

Shape: Indefinite; particles slide past each other and take the shape of their container.
Volume: Definite

Question 8

Describe a gas in terms of shape and volume.

Answer 8

Shape: Indefinite - particles take the shape of their container.
Volume: Indefinite - the volume of the same amount of gas can change.

Question 9

Describe a solid in terms of particle movement and energy level.

Answer 9

Solid
Particle movement: Particles do not move fast enough to overcome the attraction between them; particles vibrate and are locked in place
Energy level: Low

Question 10

Describe a liquid in terms of particle movement and energy level.

Answer 10

Liquid
Particle movement: Particles move fast enough to overcome some of the attraction between them; particles are able to slide past each other and take the shape of their container
Energy level: Medium

Question 11

Describe a gas in terms of particle movement and energy level.

Answer 11

Gas
Particle movement: Particle move fast enough to overcome all of the attraction between them; particles are spread out and move independently
Energy level: High

Question 12

What is a crystalline solid?

Answer 12

A solid whose particles are arranged in an orderly, three-dimensional, repeating pattern.

Question 13

What is an amorphous solid?

Answer 13

A solid whose particles do not have a specific pattern or arrangement.

Question 14

What is the viscosity of a liquid?

Answer 14

The ability of a liquid to pour - a measure of how fast a liquid flows

Question 15

What makes a liquid have a high viscosity?

What makes a liquid have a low viscosity?

Answer 15

When its particles have a large amount of attraction between them.

When its particles have a small amount of attraction between them.

Question 16

What is surface tension?

Answer 16

The force acting on the surface of a liquid that forms spherical drops and minimizes its area.

Question 17

Which changes of state make a substance’s particles more ordered?

Answer 17

Exothermic changes(Freezing and Condensation); as energy is removed, the substance’s temperature decreases, which causes the particles of a substance to slow down and have a greater attraction between them. Consequently, the particles become more ordered.

Question 18

Describe freezing (4 things)

Answer 18

1. The change of state from a liquid to a solid
2. Exothermic change - Energy is removed
3. The reverse of melting - a substance has the same melting and freezing points
4. By removing energy from the liquid, its temperature decreases, causing its particles to slow down. The slow movement of the particles prevents them from overcoming some of the attraction between them. Consequently, the particles lock together and vibrate in place, forming a solid.

Question 19

Describe Melting (4 Things)

Answer 19

1. The change of state from a solid to a liquid
2. Endothermic change - energy is gained
3. The reverse of freezing - a substance’s freezing point and melting point are the same.
4. When the solid gains energy, its temperature increases, causing its particles to speed up. The particles are able to move quickly enough to overcome some of the attraction between them. The particles are able to spread out and slide past each other, forming a liquid.

Question 20

Describe Evaporation (4 Things)

Answer 20

1. The change of state from a liquid to a gas
2. Endothermic change - energy is gained
3. The reverse of condensation - a substance’s evaporation point and condensation point are the same.
4. When the liquid gains energy, its temperature increasing, causing its particles to speed up. The particles are able to move quickly enough to overcome all of the attraction between them. The particles are able to spread out and move independently, forming a gas.

Question 21

Describe condensation (4 Things)

Answer 21

1. The change of state from a gas to a liquid.
2. Exothermic change - energy is removed
3. The reverse of evaporation - the boiling (total evaportion) point and condensation point of a substance is the same.
4. When energy is removed from the gas, its temperature decreases, causing its particles to slow down. The particles are not able to overcome all of the attraction between them, so they start to clump together. Eventually, the all of the particles of the gas combine so they can slide past each other, forming a liquid.

Question 22

Describe sublimation (3 Things)

Answer 22

1. The change of state from a solid directly to a gas.
2. Endothermic change - energy is gained.
3. A substance’s particles go from a solid (particles are moving slowly, being very close together, having a lot of attraction between them) to a gas (particles have no attraction between them, move very quickly, and move independently) very quickly

Question 23

What is the pressure of a gas?

Answer 23

A measure of how tightly packed a gas’s particles are. In other words, it is a measure of how often particles collide with the inside walls of the container as they move.

Question 24

What is the temperature of a substance?

Answer 24

A measure of how quickly a substance’s particles move.

Question 25

What is the difference between evaporation and boiling?

Answer 25

Evaporation - the change of state from a liquid to a gas. Evaporation can occur below the boiling point of a substance, in which the particles on the surface of the liquid move fast enough to overcome the attraction between them and become a gas. Boiling - the change of a liquid to a vapor throughout the entire liquid. Boiling is the complete evaporation of a liquid (the entire substance evaporates). Boiling occurs at or above the boiling point of the substance.

Question 26

Why is the melting point of a substance the same as its freezing point?

Answer 26

Because freezing and melting are reverses of each other, they both share the same freezing/melting point. If the temperature of a substance is 0°C, Whether energy is gained or removed determines if the substance will freeze or melt. Freezing point - 0°C and below - If energy is removed from liquid water at 0°C, then the water will freeze. Melting point - 0°C and above - If energy is given to ice at 0°C, then the ice will melt. * Energy can be given to liquid water at 0°C, and no change of state will occur.

Question 27

What does Boyle's Law state?

Answer 27

The volume of a gas is inversely proportional to its pressure when temperature remains constant.

Question 28

What does Charles's Law state?

Answer 28

The temperature of a gas is directly proportional to its volume if pressure is constant.

Question 29

If a balloon is taken out on a cold day, what will happen to the volume of the balloon?

Answer 29

The temperature of the gas decreases, causing its particles to slow down, which decreases the amount of times the particles hit the inside of the balloon, therefore decreasing pressure. Because pressure must remain constant, the volume of the balloon must decrease to increase the amount of times the particles hit the inside of the balloon, therefore increasing the pressure back to the way it was. So, the volume of the balloon will decrease when the temperature decreases according to Charles's Law.

Question 30

If the volume of a gas decreases, then what will happen to its temperature if pressure is constant?

Answer 30

The temperature will also decrease by Charles's Law.

Question 31

If the pressure of a gas decreases, then what will happen to its volume if temperature is constant?

Answer 31

The volume of the gas will increase according to Boyle's Law

Question 32

If the temperature of a gas increase, then what will happen to its volume if pressure is constant?

Answer 32

The volume of the gas will increase according to Charles's Law.

Question 33

If the volume of a gas increases, then what will happen to its pressure if temperature is constant?

Answer 33

The pressure will decrease according to Boyle's Law.