An ice cube at its freezing point is placed in nested Styrafoam cups which contain 240 g of water at 21.5 °C. If the final equilibrium temperature when the last trace of ice melts is 25.0 °C, what was the mass of the ice cube?

Answer 1

The sum of heats gained is zero.
massice=m
m*Hf+m*c*(25-0)+240*C*(25-21.5)=0
solve for m