Illustrated Glossary of Organic Chemistry

Heat capacity: The amount of energy required to raise the temperature of a substance by a given amount. The International System of Units (SI) unit for heat capacity is joules per kelvin (J K^-1).

The standard heat capacity of ice is 2.03 J K^-1 g^-1. This is the amount of energy it will absorb as it cools the drink. Eventually the entire system (drink diluted with water from melted ice, the glass, and the surrounding air) will reach equilibrium (all will be at the same temperature). Then its time for more ice!