Freezing water is an exothermic process. This might seem counterintuitive at first, but let’s break it down.
When water freezes, it changes from a liquid to a solid state. During this transition, the water molecules lose energy and come closer together to form ice. As the molecules slow down and arrange themselves into a solid structure, they release energy in the form of heat into the surrounding environment.
This release of heat is what makes the freezing process exothermic. Essentially, the water is expelling energy as it transitions to a lower energy state (ice). You can observe this phenomenon if you put a container of water in a freezer; the area around it may get colder because the water releases heat to its surroundings as it freezes.
In summary, since energy is released when water freezes, freezing is classified as an exothermic process.