Question #af560

1 Answer
May 2, 2017

It doesn't!


Boiling point is the temperature at which the vapour pressure of a liquid is the same as the external pressure surrounding it. At this temperature the liquid changes to a vapour.

The value of the external pressure affects the boiling point. If external pressure is reduced (e.g. at the top of a mountain) then liquids will boil at lower temperatures. Or if external pressure is increased (e.g. in a pressure cooker) liquids boil at higher temperatures.

However, the way that heat is applied to the liquid has no impact on boiling point. If the source of the heat is some distance from the liquid that is being heated, some of the heat energy will be wasted in warming up the external environment, so it will take longer to reach the boiling point. The boiling point does not change, however.