Amateur chefs everywhere seem to swear by it, and some professional chefs do too. You put your spiffy new pot full of water on the stove, fire up the burners, and just as it’s heating up, you toss a pinch of salt in to speed up the process to boil some delicious pasta. But wait a second, will adding salt to boiling water actually make the water boil faster? What does the salt do to the water to allegedly achieve this?
Well, all the pro-salters are out of luck. In fact, adding salt does the very opposite of making water boil faster. Instead, it makes it take longer for the water to boil! The salt actually increases the boiling point of the water, which is when the tendency for the water to evaporate is greater than the tendency for it to remain a liquid on a molecular level.
When the salt is added, a phenomenon known as “boiling point elevation” is put into effect, which involves those old chemistry mainstays—the solute, solvent, and solution. Boiling point elevation happens when a non-volatile solute (or a dissolvable substance—in this case, the salt) is added to a pure solvent (or a substance that dissolves a solute—in this case, the water itself) to create a solution (the salt water).
The salt water requires more exposure to the heat in order to boil than water alone, so the boiling point is elevated and the time it takes to get the water to boil increases. This makes the water hotter (the new boiling point is increased to about 216° F, as opposed to the standard 212° F for unsalted water), but it still doesn’t make it boil faster.
If you want to add some additional flavor or take some extra time to get other prep work done in the kitchen, make sure to throw a dash of salt in there. But if you want your water to boil faster, just leave it as is.