Question

Which compounds show negative deviation from Raoult's law?

Answer 1

Raoult's law:

• “Raoult’s law states that for a solution of volatile liquids, the partial vapor pressure of each component of the solution is directly proportional to its mole fraction present in the solution.”
• It can be expressed as:
• $$\begin{gathered} p_{\mathit{1}}\mathit{\propto }{x}_{\mathit{1}} \\ and\mathit{}{p}_{\mathit{1}}\mathit{=}{p_{\mathit{1}}}^{\mathit{0}}{x}_{\mathit{1}} \end{gathered}$$
• Where $p_{\mathit{1}}$ is the partial pressure of the pure component 1 and $x_{\mathit{1}}$ is the mol fraction for component 1 and ${p_{\mathit{1}}}^{\mathit{0}}$ is the vapor pressure of the pure component 1.

Compound that shows a negative deviation from Raoult's law:

• The compounds which show negative deviation from Raoult’s law are a mixture of acetone and chloroform, this results in the formation of the hydrogen bonding between atoms of the molecules.
• There is a decrease in the vapor pressure of the mixture that results in the negative deviation from Raoult's law.