Quantity of heat energy required for change of phase = (mass) x (heat of fusion or heat of vaporization), or in equation form,
Q=mL
Quantity of heat energy responsible for a temperature change = (mass) x (specific heat) x (change in temperature), or in equation form,
Q=mcΔT
For water, heat of fusion = 80 cal/g; heat of vaporization = 540 cal/g. Calculate the energy released by 20 grams of
100∘C
steam that condenses and then cools to
0∘C.