A 50g ice cube initially at 0∘C is gently placed on a large, thick metal plate that is uniformly at 25∘C. The plate is so massive that its temperature remains essentially unchanged while the ice melts and the resulting meltwater warms to 25∘C. Ignore any energy exchange with the surrounding air.
(a) Describe the direction of thermal energy transfer between the metal plate and the ice–water mixture while the process occurs.
(b) If the system is defined to be the ice–water mixture only, identify whether the process is heating or cooling for that system. Justify your answer in terms of the sign convention for thermal energy transfer Q.
(c) Redefine the system to be the combination of the ice–water mixture and the portion of the metal plate that cools. For this larger system, state whether heating or cooling occurs and explain your reasoning.
(d) Once the meltwater has reached 25∘C, explain why the system and the plate are said to be in thermal equilibrium.