10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H2O at 18.0oC. If the following reaction occurs, then what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat?
CaO(s) + H2O(l) Ca(OH)2(s), ?Horxn = -64.8 kJ/mol