What would happen to the boiling point of a substance if the elevation were to rise?

1 Answer
anor277
Jul 14, 2017

The boiling point of the substance would reduce.......

Explanation:

By definition, the boiling point of a liquid is the temperature at which the vapour pressure of the liquid is equal to the ambient pressure, and bubbles of vapour form directly in the liquid. The normal boiling point is specified when the ambient pressure is 1⋅atm, and thus the vapour pressure of the liquid is 1⋅atm at its boiling point.

I do acknowledge that this definition is wordy, and it is the level of knowledge expected of a 1st year undergraduate chemist........ But this principle underlies vacuum distillation, where we can boil an otherwise involatile liquid by reducing the ambient pressure (by applying a vacuum) and reducing the temperature at which the vapour pressure of the liquid is equal to the ambient pressure.

The highest altitude city to which I have been was Denver, Colorado, approx. 1500 m above sea level. The boiling point of water is approx. 95 ∘C here. What would you surmise with regard to atmospheric pressure in Denver? The boiling point of water on top of Mount Everest is apparently 72 ∘C (almost cold enuff to bath in-not that I would want to have bath on a snow-capped mountain). Are these facts consistent with what we have argued?

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