A vapor pressure curve is used to determine the vapor pressure of a liquid at any temperature. This curve has temperature shown on the x axis and the vapor pressure on the y axis. Each liquid has its own vapor pressure curve. For example if you look at vapor pressure curve of water and you want to find the vapor pressure of water at 60 C, then read the vapor pressure on y axis for the temp 60C on the x axis. It shows the vapor pressure as 400 mm Hg.
The vapor pressure curve is also used to find the boiling point of a liquid. For example if you want to find the boiling point of water at 760 mm Hg, you can locate the boiling temperature by going across the 760 mm Hg pressure and find the boiling temp as 100 C. You can also see from the curve that the temperature at which a liquid boils varies with the pressure. So when you specify the boiling point of a liquid, you must also specify the pressure of the liquid.
Dec 5th, 2014
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