The latent heat of vaporization of steam is equal to its latent heat of condensation. The heat released is given by:
Q = ml
Q = 20 x 2257 joules/gram
Q = 45.14 kJ of heat is removed from the steam
1 calorie = 4.184 kJ
45.14 kJ = 10.8 cal of energy
The energy removed is 10.8 calories
