Question

Which is a practical application of boiling-point elevation?

A. Cooling a supersaturated sugar-and-water solution to form rock candy.

B. Burning coal to make the steam that powers a steam engine.

C. Adding antifreeze to water in a car radiator in summer to raise the boiling point.

D. Boiling sea water to recover the salt it contains.

Answer 1

Boiling-point is the point of a pure liquid matter starts to evaporate and change into gaseous phase. It is where the set of conditions such as the pressure and temperature enough to do so. Boiling-point elevation, on the other hand, is the phenomenon of which the boiling point of a pure liquid matter is elevated because of the dissolved substances. A great example would be the boiling point of a distilled water (pure water) which is lesser than the boiling point of a sea water because of the dissolved salts. A pure water boils at 100°C at atmospheric pressure while a salt water boils at higher temperature than 100°C at the same pressure. Thus, the answer is D.