Specific Latent heat

Question 1

What is Specific Latent Heat?

Answer 1

The energy needed to change to change the state of a substance.

Question 2

What does a change of state require?

Answer 2

Energy.

Question 3

Why are there flat spots on the heating graph?

Answer 3

Energy is still being transferred by heating (And so increasing the internal energy), but the energy is used for breaking inter molecular bonds, rather than raising the temperature.

Question 4

When a substance is condensing or freezing, what is happening?

Answer 4

Bonds are forming between particles, which releases energy. The flat points on the graph show where the internal energy decreases, but the temperature doesn’t go down, until all the substance has turned to liquid (condensing) or a solid (freezing).

Question 5

The specific latent heat of a substance is …

Answer 5

the AMOUNT OF ENERGY needed to change 1 kg of it FROM ONE STATE TO ANOTHER WITHOUT CHANGING ITS TEMPERATURE. (the flat parts of the graph)

Question 6

The specific LATENT HEAT OF VAPORISATION of a substance is…

Answer 6

The energy needed to change the state of 1 Kg of a substance from liquid to vapour, at its boiling point(without changing its temperature.)

Question 7

The unit of S.L.H of vaporisation is…

Answer 7

J/Kg

Joules per kilogram.