What is the rule about the relationship between phase changes and tempurature? Between phase changes and heat energy??

When you are heating a body which changes phase, the temperature of the body will remain constant until all the changes have been made.

Take for example water boiling at 100 Celsius. At 100 degrees Celsius, the temperature of the water will no longer rise. However, it will turn to steam. When all the water has been converted to steam, then the temperature of the steam will start rising again. The formula for this is:



where Q is the amount of heat in joules
m the mass of the substance
L the specific latent heat of the substance.