P1.2 Changes Of State

Question 1

Difference between energy and temperature

Answer 1

The energy in a thermal store is measured in joules. It depends on the arrangement of the particles and how fast they are moving or vibrating. Temperature tells you about the average kinetic energy of the particles.

Question 2

Specific heat capacity definition and formula

Answer 2

Specific heat capacity is the energy needed to raise the temperature of 1kg of a material by 1K (degree celsius).
Specific heat capacity tells you how resistant a material is to a change in temperature.
E = m x c x delta T

Question 3

Explain the changes on a graph when ice melts and boils

Answer 3

The temperature of ice increases as it is heated up. At 0 degrees celsius it stays the same temperature since the ice is melting. All energy is being used to break the intermolecular forces between the molecules rather than increase the temperature. Once all the ice has melted into water, the energy being put in increases the temperature of the water until it reaches 100 degrees celsius. The temperature now stays the same as the water is being boiled. All energy is being used to break the intermolecular forces between the water molecules. After all the water has boiled, the temperature of water vapour increases again.

Question 4

Specific latent heat of fusion

Answer 4

The specific latent heat of fusion is the energy transferred when 1kg of a substance changes from the solid state into the liquid state, or vice versa.

Question 5

Specific latent heat of vaporisation

Answer 5

The specific latent heat of vaporisation is the energy transferred when 1kg of a substance changes from liquid state to gas state.

Question 6

Formula for specific latent heat

Answer 6

E = m x L