Answer to Question #120010 in Physics for Susan Williams

Question

Explain why it is better to use ice at 00C than an equal mass of water at 00C to cool warm water

Answer 1

When cold water at 00C is added to the warm water, some energy is passed from the warm to the cold water. As a result, the temperature of both amounts of water starts to change immediately and eventually becomes the same.

On the contrary, in case of adding the same amount of ice at 00C, some energy must be spend to melt the ice first. During the melting, the temperature of the ice remains the same – 00C, while the temperature of the hot water decreases. When all ice is melted away, we have the same amount of cold water at 00C remains as at the start of the previous case. But now the temperature of the surrounding warm water becomes less, for some heat energy has been already consumed by the ice.

Thus, is better to use ice because it can consume more heat energy then the equal mass of water at 00C.