Thermal Properties of Matter

Question 1

Define Heat Capacity (scalar), C

Answer 1

It is the amount of thermal energy required to raise the temperature of a substance by 1K or 1°C.

Question 2

SI unit of Heat Capacity

Answer 2

J/°C or J/K

Question 3

Formula for Heat Capacity

Answer 3

C=Q/change of temperature or C=mc

Question 4

Define Specific Heat Capacity (scalar)

Answer 4

It is the amount of thermal energy required to raise the temperature of 1 kg (unit mass) of a substance by 1 K or 1 °C.

Question 5

SI units of Specific Heat Capacity

Answer 5

J/kg°C or J/kgK

Question 6

Formula for Specific Heat Capacity

Answer 6

c= Q/mass x change in temperature

Question 7

Define Latent Heat of fusion (scalar)

Answer 7

It’s defined as the amount of thermal energy required to change the state of a substance from solid to liquid, or vice versa, without any change of temperature.

Question 8

Define Latent Heat of vaporisation

Answer 8

It’s defined as the amount of thermal energy required to change the state of a substance from liquid to gas, or vice versa, without any change of temperature.

Question 9

SI unit for Latent Heat

Answer 9

J (Joule)

Question 10

Define Specific Latent Heat of Fusion

Answer 10

It’s defined as the amount of thermal energy required to change 1kg of solid to liquid, without any change of temperature.

Question 11

Define Specific Latent Heat of Vaporisation

Answer 11

It is defined as the amount of thermal energy required to change 1kg of liquid to vapour, without any change in temperature.

Question 12

SI unit of Specific Latent Heat (Scalar)

Answer 12

J/kg

Question 13

Formula for Specific Latent Heat (scalar)

Answer 13

ℓ=Q/m

Question 14

Define melting

Answer 14

Process whereby energy is supplied by a source to change the state of a substance from solid to liquid without a change in temperature.

Question 15

Define Freezing

Answer 15

A process whereby energy is absorbed by the surroundings to change the state of a substance from liquid to solid without a change in temperature.

Question 16

Define Boiling

Answer 16

A process whereby energy is supplied to change the state of a substance from liquid to gas without a change in temperature

Question 17

Define Condensation

Answer 17

A process whereby energy is absorbed to change the state of a substance from gas to liquid without a change in temperature.

Question 18

Differences between Boiling and Evaporation (4 differences)

Answer 18

1. Boiling is fast, condensation is slow
2. During Boiling bubbles are formed throughout the liquid, whereas, as evaporation takes place only at the surface, no bubbles are seen in evaporation.
3. Boiling occurs at 1 temperature, the boiling point, whereas evaporation occurs at any temperature between the melting and boiling point.
4. Boiling requires an external heat source, evaporation takes in heat from surrounding.

Question 19

Factors of surrounding air affecting evaporation

Answer 19

1. Temperature of surrounding air
2. Humidity of surrounding air
3. Pressure of surrounding air
4. Motion of air above liquid

Question 20

Factors of liquid affecting evaporation

Answer 20

1. Temperature of liquid.
2. Nature of liquid (volatility)
3. Surface area of liquid