# Why is freezing an exothermic process?

Mar 16, 2014

In this process of freezing, water loses heat to the surroundings, so it is an exothermic process.

#### Explanation:

Freezing is a process of liquid changing its state to solid. Let's scrutinize the process closely.

Let's start with water. A cup of water contains a large amount of tiny $\text{H"_2"O}$ molecules. Each tiny molecule is moving and has some amount of energy. When the water is placed in a freezer, the water slowly loses heat to the surrounding cold air. The water molecules on losing energy begin to move slowly, come closer and pack close enough to change to ice.

In this process, the water releases heat to the surroundings, so it is an exothermic process.

When water lose energy, the individual molecules move slower (decreased kinetic energy). Eventually the water molecules will become locked in place (freeze) as they maximize the number of hydrogen bonds they form with other water molecules.