How much heat must be removed to freeze a tray of ice cubes at 0 C if the water has a mass of 225 g?
Well, if the tray itself has a negligible heat capacity...
...then we ignore it and focus on the ice, which has an unstated enthalpy of fusion of
Hence, the amount of heat that is released at constant pressure is:
#color(blue)(|q_"removed"|) = "6.02 kJ"/cancel"mol" xx cancel"1 mol"/(18.015 cancel"g water") xx 225 cancel"g" = color(blue)"75.2 kJ"#
At constant pressure,
HINT: read the question wording again. Which direction is the heat flowing, and is the ice the system or surroundings?