What happens when a cup of water goes in the freezer?

When a cup of water is placed in the freezer, several physical and chemical changes occur as the water cools and freezes. Here's what happens:

Cooling:

As the cup enters the freezer, the cold air inside begins to extract heat from the water. The water molecules slow down in their motion, and their kinetic energy decreases. The temperature of the water starts to drop.

Supercooling:

In some cases, water can undergo a phenomenon called "supercooling." When water is cooled below its freezing point (0 degrees Celsius or 32 degrees Fahrenheit) without forming ice crystals, it is said to be supercooled. This can happen if there are no nucleation sites, such as dust particles or scratches on the container, where ice crystals can start to grow.

Nucleation:

Eventually, nucleation occurs, and tiny ice crystals form around nucleation sites in the water. The initial ice crystals can be very small, like microscopic needles or grains. Their formation releases latent heat of fusion, which is the energy that was required to break the bonds between water molecules in the liquid state.

Crystal Growth:

As more ice crystals form, they continue to grow through a process called "crystal growth." The water molecules next to the ice crystals are attracted to their orderly structure and join the growing ice lattice, releasing more latent heat. This growth process continues until a significant portion of the water transforms into solid ice.

Phase Transition:

As more and more water molecules are incorporated into the ice crystals, the phase transition from liquid water to solid ice progresses. The freezing point of water can vary slightly based on environmental conditions like air pressure and impurities, but typically this transition occurs around the freezing point (0 degrees Celsius or 32 degrees Fahrenheit).

Expansion:

An interesting property of water is that its density decreases as it freezes. This means that ice is less dense than liquid water. As water turns into ice, it undergoes a slight expansion in volume, about 9% increase compared to its liquid state. This is often the reason behind burst water pipes or cracked outdoor containers during freezing conditions.

The final state of the cup of water is a mixture of ice crystals and remaining liquid water if not all of the water has frozen solid. The amount of ice formed depends on how long the water is left in the freezer and the temperature settings.

Note: The cooling rate and the specific conditions within the freezer, such as air circulation and freezer temperature stability, can influence the appearance and structure of the ice formed.