0.115 kg of water at 81.0o C is poured into an insulated cup containing 0.220 kg of ice initally at 0o. Calculate the mass of liquid when the system reaches thermal equilibrium.

Answer 1

In this case, not all of the ice melts. Let m be the number of grams of ice that melts.
115*81*1.0 = m*80
(80 cal/g is the heat of fusion)
m = 116 g
Note that is less than the amount of ice you started out with. So there is some ice left.
Add that to the 115 g of liquid water you had at the beginning.