Question

Why do pieces of ice add to a drink, rather than water at 0°C, so as to cool it?

Answer 1

Ice cools a drink more effectively than water at 0°C because it must first absorb the latent heat of fusion to melt. When 1 kg of ice at 0°C melts, it absorbs 336000 J of heat energy without any rise in temperature. This heat is taken from the drink, causing extra cooling. After melting, the water formed is at 0°C and further absorbs sensible heat as it warms up. Water at 0°C, by contrast, can only absorb sensible heat as it warms up; it provides no latent heat effect. Thus, ice removes more heat from the drink per unit mass than water at 0°C, so it cools the drink faster and more effectively.