急F.4 Specific latent heat 計算一題

Yunnan Guoquao-mixian is a famous Chinese food. In preparing the food, the first step is to cook a pot of chicken soup: A pot of water containing chickens is heated over a high flame until it boils. A low flame is then used to keep thesoup boiling for 3 hours.

The power output of the low flame is 300 W. If 70% of the energy supplied is lost to the surroundings, caculate the mass of the soup that would be vaporized after being heated for 3 hours. Assume the specific heat latent heat of vaporization of the soup is 2.26 X 10^6 J kg^-1