Science Project: Does Water With Salt Boil Faster Than Plain Water?

Because many pasta and potato recipes call for salt to be added to water before boiling, many people erroneously think that this is intended to make the water boil faster.

Experiment

At home, even with the water and salt measured into exactly equal proportion, it would be difficult to tell for sure which of two pots boiled first. There is also the matter of environmental discrepancies, such as uneven stove burners, pots with bottoms of different thicknesses.

Temperature

The addition of salt to water actually raises its boiling temperature. For every ounce of salt to gallon of boiling water, the boiling temperature of the water is raised about 17 degrees Fahrenheit. In fact, any non-volatile substance raises the boiling point of water—that is why you add ethylene glycol (antifreeze) to car engines in the winter.

Why Salt?

The reason we add salt to boiling water for pasta and potatoes is mainly to add flavor. Technically, if enough salt was added, it could speed up the cooking time of the pasta. However, that would make the pasta too salty to eat.

References

• Department of Energy: Ask a Scientist: Salt and Boiling Water II