Heat and change of physical state - Concept of Freezing (Solidification)

Freezing is when a liquid, like water, turns into a solid, like ice. When you put water in the fridge or on ice, its temperature starts falling, and it becomes cooler. As the water cools down, it reaches a point where it doesn’t get any cooler, but instead, it begins to freeze and turn into ice. This happens at a specific temperature, called the freezing point of water. For pure water, the freezing point is 0°C. At this temperature, water turns into ice.

• Each substance also has a specific melting point (the temperature where it melts) and freezing point (the temperature where it freezes), which are the same. For example, water freezes at 0°C and melts at 0°C.
• For example, when ice gets heat, it melts and turns into liquid water at 0°C.
• Temperatures can go below 0°C. For example, the freezer in a fridge has a temperature of around -18°C. At this low temperature, the water stays frozen as ice.

Every substance has a specific boiling point, which is the temperature at which it changes from liquid to gas. This temperature is the same as its condensation point, where the gas changes back into a liquid. For example, the boiling point of water is 100°C, and the condensation point is also 100°C.