1. The problem statement, all variables and given/known data What mass of steam at 100 degree celsius must be passed into 5.4 kg of water at 30 degree celsius to raise temperature of water to 80 degree celsius? 2. Relevant equations C(water)=4.2 J/(g C) L(steam)=2268 J/g 3. The attempt at a solution Assuming no heat loss, Heat gained by water=Heat given by steam by changing to water+ heat released by water so formed to fall from 100 degree to 80 degree 5.4*50*4200=m*2268000+m*4200*20 1134000=m(2352000) m=0.482142857 Kg My book gives me the answer as 0.5 Kg. It neglects the heat given by water formed from steam, it seems. why?????