The freezing temperature of water depends on several factors, including the pressure and purity of the water. The freezing point of pure water is 0 degrees Celsius (32 degrees Fahrenheit), but it will freeze at lower temperatures if it contains impurities.

Pure water freezes at 0 degrees Celsius because that’s the temperature at which the liquid and solid phases become equal in energy. It’s impossible for a substance to exist as both a liquid and a solid at the same time. When you cool down pure water below 0 degrees Celsius, its molecules slow down until they have zero kinetic energy, which means they can’t move anymore. That’s when they transform into ice crystals and form ice cubes.

When you cool down impure water below 0 degrees Celsius, some of its molecules will turn into ice crystals while others remain in the liquid phase. This means that not all of the impurities are frozen in place with each other within an ice cube — instead, they’re floating around freely in the liquid phase while they cool down to 0 degrees Celsius. This is why some types of impurities make ice melt more quickly than pure water does: because some of them can exist as both a liquid and solid phase at room temperature, which means there are.

Last modified: September 4, 2022