Why does the presence of salt higher the boiling point of water?
When salt is added to water, the boiling point of the water rises and the freezing point is lowered. From a molecular standpoint, when water temperature rises, the molecules move faster, collide more frequently, and release more vapor gas molecules. Salt chemical ions take up some space, making for fewer collisions among water molecules, so they do not release as many vapor molecules as pure water would. Thus, more energy is required–a higher temperature–for salty water to start to boil. So, raising the boiling point of 1 liter (34 oz.) of water by 1 degree C (1.8 degrees F) requires about 58 grams (2 oz.) of salt.
