Question

The enthaply of fusion of ice is 334 J/g. The heat capacity of liquid water is 4.18 j/gxC. What is the smallest number of ice cubes at 0C, each containing one mole of water necessary to cool 500 g of liquid water intially at 20 C to 0 C?

Answer 1

molar mass of water = 18g/mole

no of moles of H2O = W/G.M.Wt

                                  = 500/18   = 27.8 moles

27.8 moles of water cool to 20C to 0C

heat capacity of water = 75.4J/mole-C⁰

   q   = n*C*T

         = 27.8*75.4*(20-0)

        = 41922.4 J   = 41.9224kj

Enthalpy of fusion of ice 6.02KJ/mole-C⁰

no of moles of ice cubes = 41.9224/6.02   = 7 moles of ice cubes