Physics AQA Topic 3 (Internal energy and transfers)

4.3.2

What is internal energy of a substance

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

How does heating affect the energy of a substance

Heating transfers energy to the substance and increases the energy of the particles that make up the substance

What two things can heating a substance do

Raise its temperature and change the state of the substance

What three factors determine the temperature change of a system

Mass of a substance being heated, type of material (specific heat capacity) and the energy inputted into the system

State the equation used to calculate the temperature change when a substance is heated

∆E = mc∆θ (Change in energy = mass x specific heat capacity x change in temperature)

What are the units for the equation used to calculate the temperature change

Change in thermal energy = joules (J), mass = kilograms (kg), specific heat capacity = joules per kilogram degree Celsius (J/kg^C), temperature change = degrees Celsius (^C)

Define specific heat capacity

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

Describe how the internal energy and temperature of a substance changes when a change of state occurs

The internal energy of the substance will be increased or decreased - the temperature of the substance will remain constant

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

E = mL (energy to change state = mass x specific latent heat)

Give the units for the equation for the energy required to change state

Energy = joules (J), mass = kilogram (kg), specific latent heat (J/kg)

What is the specific latent heat of fusion

The energy required to change 1kg of a substance from solid state to liquid state without a change in temperature

What is the specific latent heat of vaporisation

The energy required to change 1kg of a substance from liquid state to gas state without a change in temperature