Final answer:
The temperature of a glass of pure ice water with ice cubes floating in it would be 0 degrees Celsius, as it is in thermal equilibrium with the melting ice maintaining a constant temperature until all the ice has melted.
Step-by-step explanation:
If you have a pure glass of ice water, consisting of ice cubes floating in water, the temperature of the mixture would be 0 degrees Celsius. When ice is at the melting point, it begins to change into liquid water at the same temperature, maintaining equilibrium.
This is due to the fact that as long as there is ice present in the water, the combination of ice and liquid water are in a state of thermal equilibrium, meaning no net change in state occurs until either all the ice melts or additional heat is added to the system. As heat enters the glass, it is used to slowly melt the ice rather than increase the temperature of the water until all the ice has melted.
This thermal property is due to the enthalpy of fusion of ice, which is the energy required to cause a phase change at constant temperature. Additionally, the density of ice is lower than water, causing the ice to float, which is related to its molecular structure and hydrogen bonding. Only when all the ice is melted will the water temperature start to rise.