You may have heard this and wondered if it was true. Here is a look at the science behind salt and boiling water.
It is not a scientific fact that adding salt to water lowers its boiling point. Actually, the opposite is true. Adding salt to water results in a phenomenon called boiling point elevation. The boiling point of water is increased slightly, but not enough that you would notice the temperature difference. The usual boiling point of water is 100°C or 212° F at 1 atmosphere of pressure, which is the pressure at sea level.
To raise the boiling point of a litre of water by one half of a degree Celsius ( ½°C), you would have to add 58 grams of salt – that is slightly more than half the content of a 100g sachet of Annapurna salt. Basically, the amount of salt people add to water for cooking doesn’t affect the boiling point at all.
Some Quick Facts
- Salt, known chemically as sodium chloride, is an ionic compound that breaks apart into its component ions (Na+ Cl-) in water. These ions affect how water molecules (H+ O2-) interact with each other, yet this effect on water molecules is not restricted to salt alone. Adding any other compound to water, or any liquid for that matter – increases its boiling point.
- If you add salt to water, be sure to add it before boiling the water. Adding salt to water that is already boiling may cause the water to splash up and boil more vigorously for a few seconds.