internal energy and energy transfers

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 system

How does heating affect the energy of a substance?

● Heating transfers energy to the

substance

● It increases the energy of the particles that make up the substance

What two things can heating a substance do?

1. Raise its temperature

2. Change the state of the substance

What three factors determine the

temperature change of a system?

1. Mass of substance being heated

2. Type of material (Specific heat

capacity)

3. Energy inputted into the system

State the equation used to calculate the temperature change when a substance is heated. Give appropriate units.

● ΔE = m c Δ𝛉

● Energy (J), Mass (kg), Specific Heat Capacity (J/kg/°C), Temperature (°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. Give

appropriate units.

● Energy to change state = mass x specific latent heat

● Energy (J), Mass (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 (vapour) without a change in temperature.