changes of state & specific latent heat

Question 1

what is specific latent heat?

Answer 1

the amount of energy needed to change 1 kg of it from one state to another without changing its temperature

Question 2

when a change in state happens, what does the energy supplied change and what doesn’t it change?

Answer 2

the energy stored (internal energy), but not temp

Question 3

equation

Answer 3

energy for a change in state = mass x latent heat

Question 4

what is the specific latent heat of fusion?

Answer 4

change of state from solid to liquid

Question 5

what is the specific latent heat of vaporisation?

Answer 5

change of state from liquid to
vapour

Question 6

what happens when a substance is melting or boiling to do with energy + heating graphs?

Answer 6

• still putting energy in so increasing internal energy
• but energy is used for breaking bonds between particles rather than raising the temperature
• flat spots on heating graph where energy is being transferred by heating but not being used to change temp

Question 7

what happens when a substance is condensing or freezing to do with energy + cooling graphs?

Answer 7

• bonds are forming between particles, which releases energy
• means internal energy decreases but temp doesn’t decrease until all the substance has turned to liquid or solid
• flat parts of graph show energy transfer