How Ice Cubes Cool Your Tea: A Simple Thermodynamics Explanation

When a pitcher of hot tea is poured over ice cubes, the tea’s thermal energy flows into the colder ice. The molecules of the tea slow down while the ice’s molecules speed up, some even leaving the solid to mix with the liquid. The tea loses heat and drops toward 32 °F, the melting point of ice. At that temperature the ice can no longer absorb more energy as a solid; instead, the absorbed heat turns it into 32 °F water. The process continues until the entire mixture reaches the same temperature, simultaneously cooling the drink and diluting it. This illustrates the conservation of energy and the second law of thermodynamics, showing how heat naturally moves from hotter to cooler bodies.