3.3
3.3
3.3.1
Phase change
Latent heat of fusion
Latent heat of vapourisation
Use latent heats in an energy calculation
3.3.2
With the current fashion in wood fuelled stoves perhaps you have noticed logs piled up outside a house.
This video provides some surprising results about heating with wood fuel and how important it is to dry the wood before burning
3.3.3
The video suggested that dry wood contains 45% more energy than wet wood! Can this be true?
To understand this we need to learn more about the energy required to change the phase of a substance.
![]()
The energy required to change a solid into a liquid
The energy required to change a liquid into a vapour
We will discover the concept of latent heat and will learn why so-called ‘condensing’ gas boilers are more efficient than traditional designs.
3.3.4
In this unit we will again look at the transition from one phase to another, paying particular attention to the amount of energy required to change from a solid to a liquid and finally to a gas. We will review the concept of phase change and explore the energy required for phase change to occur. We will conclude by investigating a practical, real world consequence.