Question

How do vapour pressures of substances like dry ice, and water, and mercury, relate to boiling point?

Answer 1

Does a vapour pressure exist for dry ice?

Explanation:

I think it does, given that dry ice sublimes.........but under standard conditions it SUBLIMES, and DOES NOT exist in the liquid state.

And certainly a vapour pressure exists for water, and this, the so-called saturated vapour pressure is extensively tabulated. Mercury expresses a MUCH LOWER vapour pressure. Why should this be so?

As always, the boiling point of a substance is the temperature at which the vapour pressure 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, and thus also the vapour pressure of the BOILING LIQUID, is `"1 atmosphere"`.