OCR A GCSE Physics: P1.2 Changes of State

From PMT

What are the 5 main ways that a substance can change state?

Melt, Freeze, Evaporate, Condense, Sublimate

What is sublimation?

When a substance transitions from a solid straight to a gas without transitioning into a liquid in between.

What is always conserved when a substance changes state?

Mass

How does a change of state differ from a chemical change?

In a change of state, the material can return to having its previous properties if the change is reversed.

What two things can heating a substance do?

Raise its temperature, Change the state of the substance

Define specific heat capacity.

The amount of energy needed to increase the temperature of 1kg of a substance by 1°C.

What can be said about a material if it has a higher specific heat capacity?

For a constant mass, the material will need more energy to achieve a given temperature change.

Define specific latent heat.

The amount of energy needed to change the state of 1kg of a substance with no change in temperature.

State the equation for the energy required to change state. Give appropriate units.

E = mL. Energy to change state = mass x specific latent heat. Energy (J), Mass (kg), Specific latent heat (J/kg)

What is the internal energy of a substance?

The energy stored by the particles. The sum of the total kinetic and potential energies that make up the sys