So, I am taking my first chemistry class and I started learning about Raoult's Law and it states that, when a non volatile solute is added to a solvent, the vapor pressure of the solvent decreases in proportion to the concentration of the solute. One consequence of this is an increase of boiling point.

So, my question is, what are the applications of this in a real-world lab setting? Genuinely asking, why do we care about decreasing vapor pressure and increasing the boiling point in a lab environment?

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    $\begingroup$ Review the guide How to ask and Asking FAQs to prevent clarification requests, objections, downvoting or closure. $\endgroup$
    – Poutnik
    Nov 13, 2023 at 4:27

1 Answer 1


I can think of one right away, that is estimating molecular masses of solutes. Further, making fractional distillation requires mole fractions in the gas phase to be different those in the solution phase, otherwise the solution forms an azeotrope which cannot be separated via fractional distillation. Moreover, Raoult law helps in understanding the bonding between solute and solvent. Deviation from the law also help in understanding our system well.

For large scale applications, and accurate lab experiments, $\Delta_\text{mix}H$ and $\Delta_\text{mix}V$ can have serious implications. Did you know that immiscibility of liquids can be explained based on large deviations from the law?

  • $\begingroup$ For further reading, you may refer to Atkin's Physical Chemistry $\endgroup$
    – ananta
    Nov 13, 2023 at 3:01

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