Solve problems involving latent heat

Understanding Specific Latent Heat

4.3

Understanding Specific Latent Heat

	Specific latent heat, \(l\) (SLH)
	The heat energy required to change phase of 1kg object at a constant temperature

	SLH of fusion
	The heat energy required to change 1kg of solid to liquid at a constant temperature

	SLH of vaporization
	The heat energy required to change 1kg of liquid to gas at consant temperature

	Formula
	\(Q=ml\), where Q = energy, m = mass, \(l\) = specific latent heat

HEATING

Temperature increase:
- Energy absorbed used to increase the average kinetic energy of molecules.
Temperature constant:
- Energy absorbed is used ot overcome the forces of attraction between molecules. Average kinetic energy of molecules does not change.

COOLING

Temperature decrease:
- Energy released decreses the average kinetic energy of molecules.
Temperature constant:
- Latent heat released to the surrounding, forces of attraction between molecules become stronger. Average kinetic energy of molecules does not change.

	Electrical energy
	\(Q=Pt\), where Q = energy, P = power, t = time

	Conservation of energy
	\(Pt=mc\Delta\theta\) \(Pt=ml\)

Understanding Specific Latent Heat

4.3

Understanding Specific Latent Heat

	Specific latent heat, \(l\) (SLH)
	The heat energy required to change phase of 1kg object at a constant temperature

	SLH of fusion
	The heat energy required to change 1kg of solid to liquid at a constant temperature

	SLH of vaporization
	The heat energy required to change 1kg of liquid to gas at consant temperature

	Formula
	\(Q=ml\), where Q = energy, m = mass, \(l\) = specific latent heat

HEATING

Temperature increase:
- Energy absorbed used to increase the average kinetic energy of molecules.
Temperature constant:
- Energy absorbed is used ot overcome the forces of attraction between molecules. Average kinetic energy of molecules does not change.

COOLING

Temperature decrease:
- Energy released decreses the average kinetic energy of molecules.
Temperature constant:
- Latent heat released to the surrounding, forces of attraction between molecules become stronger. Average kinetic energy of molecules does not change.

	Electrical energy
	\(Q=Pt\), where Q = energy, P = power, t = time

	Conservation of energy
	\(Pt=mc\Delta\theta\) \(Pt=ml\)