Salt at boiling point of water:
How much of a difference does salt make when cooking food in water, i.e. spaghetti, potatoes, rice etc.? The answer is: very little. In order for salt to make a significant difference to the boiling point of water you would have to add as much as 1 gallon of water with about twenty percent of salt. Cooked side by side with a gallon of pure water, the saltwater would boil first.
Since water has a very high heat capacity it takes a lot of energy to heat it up. This is what makes water such a great heat sink and it also helps to regulate the earth's temperature. But saltwater has a lower heat capacity than pure water, so it will take less energy to heat saltwater by one degree vs pure water. So the saltwater will naturally reach its boiling point fastest.
If you want to know the reason for the effect of salt at boiling point of water and why it has less heat capacity than pure water you need to look at its properties: one hundred grams of pure water will contain one hundred percent water, whereas the equal amount of saltwater can contain about eighty percent water and twenty percent of dissolved salt. And since dissolved salt has practically no heat capacity, you are only left with eighty grams that are made up of pure water. Thus, a twenty percent saltwater solution has only eighty percent of the heat capacity of pure water and will heat up roughly twenty three percent quicker than pure water.
Submitted by: Randy
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