As humans, we tend to take the most important things in life for granted and water makes no exception. Whether you drink it, wash with it or use it for your plants, water use makes a great part of our daily routine. But how much do we really know about water?
Hot water freezes faster than cold water.
Perhaps you have seen some of those videos on Youtube where people throw hot water into the air and it freezes instantly. In the world of science, that is called the Mpemba effect and it basically means that hot water freezes faster than cold water. The effect was named after Erasto Batholomeo Mpemba, a Tanzanian who observed the effect in 1963. While in cookery class, Mpemba noticed that the mixture of ice cream that was hot froze faster than the mixture that was cold.
He later asked physics professor Dr. Denis G. Osborne from the University College of Dar es Salaam about the effect, while participating at his lecture. While, at first, he was laughed at by his teacher, they ended up publishing his findings together in 1969. There have been many theories for the Mpemba effect, but none of them stood, until recently. Most of them, such as water evaporating and reducing volume left to freeze, impurities in the water that change its freezing point or layers of frost insulating the water, have been dismissed by experiments. In 2013, though, a team of researchers from Nanyang Technological University in Singapore published a paper where they proved that the effect was caused by hydrogen bonds being weaker in warm water and allowing it to release energy much faster.