Question

Which substance has the highest vapor pressure?

KCl, H2S, H2O or CH4

Answer 1

I think its CH4 but am not certain

Answer 2

Vapour pressure is the pressure exerted by the paricles of a gas in an enclosed container. According to the giving chemicals, CH4 is the only gasin normal state, hence this should by the one with the greates vapour pressure.

Answer 3

The way I think about it is that the lower the boiling point (or the easier a substance evaporizes), the higher the vapour pressure. The bond between K and Cl is ionic bond, so it would not evaporate easily. H2O can hydrogen bond with each other, and energy is needed to break the bond before it can evaporate. Both H2S and CH4 can evaporate easily, but H2S is heavier than CH4. So I think CH4 has the highest vapour pressure.