# Raoult's Law graphs

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#### unsung

##### Full Member
15+ Year Member
Can someone explain the Raoult's Law graphs to me. I don't understand the graphs of the deviations- i.e. when the curve is below the line, when the curve is above the line.

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When the vapor pressure lines of the individual substances the graph is showing negative deviation. When this occurs there is a greater interaction between the different liquids than there is with the same liquid. So in a mixture of X and Y, the X-Y interaction is greater than the X-X and Y-Y interaction.

Positive deviation is seen when the lines are above the theoretical line. This happens when X-X or Y-Y interactions are stronger than X-Y interactions. In ideal solutions the interactions are all equal: X-X = X-Y = Y-Y.

Wow do I love that site. Thanks a lot!

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Thanks for the site. It really simplifies the concept!!