Latent heat

The specific heat capacity of a substance is the amount of energy needed to increase the temperature of 1kg of that substance by 1 degrees Celsius.

Specific heat capacity = change in thermal energy/ (mass (kg) x maximum temp rise)

Change in internal energy = mass x specific heat capacity x temp change

heat capacity is a measure of the energy needed to change the temperature of an object by 1 degree Celsius

Thermal capacity = mass x specific heat capacity

C = m x c

Latent heat is the energy that is transferred to a substance without the substances temperature changing. This happens when a substance is changing state.

when a substance changes state, this energy is absorbed to create or weaken bonds, rather than transfer kinetic energy to a substance’s particles.

The energy is transferred without the temp changing

Specific latent heat is the latent heat per 1kg of mass

when a solid becomes a liquid or liquid becomes a solid, this hidden energy is called the latent heat of fusion.

gas to liquid/ liquid to gas, the hidden energy is called the latent heat of vaporisation

energy = mass x latent heat

mass = kg

energy change = J

latent heat = J/kg

To determine water’s specific latent heat of fusion we use the equation: specific latent heat = energy change/ mass. gently heat ice in a funnel until it melts. then measure the mass of the melted ice. measure the amount of energy supplied by the heater using a joulemeter. calculate specific latent heat.

to determine water’s specific latent heat of vaporisation we use the equation: specific latent heat = energy change/ change in mass. measure the mass of water in a beaker. Boil some water and then measure the mass of the water again. Mass at the start- mass at the end = change in mass. Measure the amount of energy supplied by the heater using a joulemeter. Calculate latent heat of vaporisation.

specific are measured per kg