how much heat (in joules) must be added to change 20.0 g of H2O (s) at -10.0 ? Cto steam at 110.0 ? C? the specific heat of H2O(s) is 2.09 J/g ?C, of H2O (l) is 4.184 J/g ?C, and of H2O (g) is 1.84 J/g ? C. The heat of fusion of water is 334.7 J/g and the heat of vaporization is 2259.4 J/g.