Problem 3-19 described four different adiabatic mixing processes, and the relevant data presented was that the enthalpy of fusion of water is 333.55 J/g, the heat capacity of ice is constant at 2.11 J/g · K, and the heat capacity of liquid water is constant at 4.19 J/g · K. Find the change in entropy of the universe resulting from each of these processes, and comment on whether each result is consistent with whether the process appears to be reversible or irreversible.

A. 100 g of liquid water at 50°C is mixed with 50 g of liquid water at 0°C.

B. 100 g of liquid water at 50°C is mixed with 50 g of ice at 0°C.C. 50 g of liquid water at 0°C is mixed with 50 g of ice at 0°C.

D. 50 g of liquid water at 20°C is mixed with 50 g of ice at –20°C.

Problem 3-19

This problem examines the effect of mixing water at two different temperatures and/or two different phases, such as dropping ice cubes into warm water. Assume that ΔH_fus 5 333.55 J/g, that C_P for ice is con stant at 2.11 J/g · K, and that C_P for liquid water is constant at 4.19 J/g · K. For each the following cases, assume the mixing is adiabatic and carried out at atmospheric pressure. For each case, determine the temperature and phase of the water when the mixing is complete. If there are two phases in equilibrium, determine the mass of each phase.