Do You Use Cold Water To Make Ice? That’s Totally Wrong, Apparently

Anyone who can remember even an iota of the Junior Cert Science curriculum will know that water freezes at zero degrees.

So it stands to reason that if you’re making ice at home, you’d use water that’s as cold as possible, to reduce the time it takes to freeze, right?

Wrong, apparently. Next time you’re making ice and want the cubes ready as fast as possible, you should probably use hot water rather than cold.

That’s according to I F***ing Love Science, who refer to something known as the Mpemba effect, or the theory that hotter water freezes faster. While the Mpemba effect has not been definitely proven as truth – sometimes cold water does still freeze faster – it does occur regularly, and scientists have come up with various reasons why.

One of the most widely supported reasons is to do with the chemical bonds that hold water together.

Each molecule of water is made up of two hydrogen atoms bonded to one oxygen atom, hence the name H2O. As well as the strong covalent bonds that hold the atoms together, there are also weaker hydrogen bonds that help the process along.

When water is heated, the weaker hydrogen bonds stretch, causing the stronger covalent bonds to relax, shrink and release their energy. This energy release is essentially what causes the water to cool.

So the stretchier the hydrogen bonds, the more energy released and the faster the water cools. Voilá!

Or, to put things in layman’s terms, it can’t hurt to use hot water next time you’re looking for ice cubes ASAP.

• ice cube
• water