Thermal Properties of Matter

Question 1

What is heat capacity

Answer 1

Heat capacity is the amount of thermal energy required to raise the temperature of a substance by 1K/degree celsius

Question 2

What is specific heat capacity

Answer 2

Specific heat capacity is the amount of thermal energy required to raise the temperature of a unit mass (e.g. 1kg) of a substance by 1K/degree celsius

Question 3

Energy transfer during melting

Answer 3

-During melting, thermal energy is absorbed to break the strong bonds between the particles of solid ice

-Only the total internal potential energy of the particles is increased

-Since internal kinetic energy does not increase, temperature remains constant

Question 4

Energy transfer during solidification

Answer 4

-During solidification, strong bonds are formed when particles move close together during freezing

-The total internal potential energy of the particles decreases as thermal energy is released and lost to the surroundings

-Since internal kinetic energy does not decrease, temperature remains constant

Question 5

What is boiling

Answer 5

Boiling is the process in which the thermal energy absorbed by a substance changes it from liquid state to gaseous state without a change in temperature

Question 6

What is condensation

Answer 6

Condensation is the process in which the thermal energy taken away from a substance changes it from gaseous state to liquid state without a change in temperature

Question 7

What is latent heat

Answer 7

Latent heat is the energy released or absorbed by a substance during a change of state, without a change in temperature

Question 8

What is latent heat of fusion

Answer 8

Latent heat of fusion is the amount of thermal energy required to change a substance from solid state to liquid state, without a change in temperature

Question 9

What is specific latent heat of fusion

Answer 9

Specific latent heat of fusion of a substance is the amount of thermal energy required to change a unit mass (e.g. 1kg) of the substance from solid stater to liquid state without a change in temperature

Question 10

Formula for latent heat of fusion

Answer 10

L = m/f

latent heat of fusion = mass x specific latent heat

Question 11

What is latent heat of vaporisation

Answer 11

Latent heat of vaporisation is the amount of thermal energy required to change a substance from liquid state to gaseous state without a change in temperature

Question 12

What is specific latent heat of vaporisation

Answer 12

Specific latent heat of vaporisation of a substance is the amount of thermal energy required to change a unit mass (e.g. 1kg) of the substance from liquid state to gaseous state without a change in temperature

Question 13

Formula for latent heat of vaporisation

Answer 13

L = m/v

latent heat of vaporisation = mass x specific latent heat

Question 14

What is evaporation

Answer 14

-Evaporation requires thermal energy from the surroundings

-It absorbs heat from the surroundings to change the state of the substance from liquid to gas

-Evaporation results in cooling

Question 15

How does evaporation occur

Answer 15

1. Molecules in liquid are in constant, random motion
2. The more energetic molecules have sufficient energy to overcome attractive forces due to other molecules to escape from the surface into the atmosphere
3. Less energetic molecules are left behind. The average kinetic energy of the molecules decreases and the temperature decreases

Question 16

Differences between boiling and evaporation

Answer 16

Boiling:
-Occurs at a specific temperature
-Takes place throughout the liquid
-Temperature remains constant

Evaporation:
-Occurs at any temperature
-Takes place at the surface of the liquid
-Temperature may change

Question 17

What affects rate of evaporation

Answer 17

-Temperature
-Pressure
-Movement of air
-Boiling point of liquid
-Surface area
-Humidity

Question 18

In case of change from state to state, use FAMED format (skip to ans)

Answer 18

F - Forces of attraction
A - Arrangement
M - Movement
E - Energy change
D - Distance