1. The problem statement, all variables and given/known data To help keep his barn warm on cold days, a farmer stores 859 kg of solar-heated water (Lf = 3.35E+5 J/kg) in barrels. For how many hours would a 2.02 kW electric space heater have to operate to provide the same amount of heat as the water does, when it cools from 11.3 to 0 °C and completely freezes? 2. Relevant equations Q=mc(deltaTdegC)+mL 3. The attempt at a solution Q=(859)(4187)(11.3)+(859)(335000) Q=328406952 J 1kW=1000W=1000J/sec 1000t=328406952 J t=328406 secs*1min/60secs*1hour/60mins=91 hours But this is wrong. What am I missing?