How much heat is required to raise the temperature of 45.5 g of water from its melting point to its boiling point?

First, melt the ice, H2O(s): 

45.5gH2O x 333J/1gH2O = 15,152 J 

Next, raise the temperature of the water, H2O(l): 

45.5gH2O x 100degC x 4.184J/1gH2O-1degC = 19,037 J 

Finally, addem all up: 

34,200 J = 34.2 kJ to three significant figures

More information