How can vapor pressure be lowered?

1 Answer
anor277
Jul 16, 2018

Just to retire this question, we can restrict the discussion to #"the saturated vapour pressure..."#, i.e. we consider the vapour pressure exerted by WATER only...

Explanation:

Now #P_"SVP"# is a function of TEMPERATURE. Of course, when water (when any liquid) boils it has a vapour pressure EQUAL to the ambient pressure, and bubbles of water vapour form directly in the liquid. And so at #100# #""^@C#, #P_"SVP"=1*atm# OR #760*mm*Hg#.

At OTHER temperatures, the vapour pressure of the water changes. Ice certainly exerts a vapour pressure. And tables of saturated vapour pressure are usually reported in #mm*Hg#. At #298*K#, liquid water exerts a vapour pressure of #24*mm*Hg#...and usually we have to account for the vapour pressures when gases (say) are collected under water. And so to reduce the vapour pressure we simply LOWER the temperature....

Now it is a fact that OTHER liquids exert a measurable vapour pressure. With respect to water, ethanol, and mercury, can you rank the vapour pressures at say laboratory temperatures....?

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