Question

What is Raoult’s law?

• A. Partial pressure of solute is constant at given temperature
• B. Partial pressure of any volatile constituent is equal to the product of vapour pressure of pure constituent and the mole fraction of the constituent.
• C. Partial pressure of volatile constituent is directly proportional to pressure applied on the solution.
• D. None of these

Answer 1

The correct option is B Partial pressure of any volatile constituent is equal to the product of vapour pressure of pure constituent and the mole fraction of the constituent.


If two volatile liquids of vapour pressures $P_A^{\circ },P_B^{\circ }$ are mixed together to form a solution,the partial pressure of on component is equal to Vapour pressure of pure component multiplied by mole fraction. According to Raoult’s Law
$P_A=P_A^{\circ }\times \frac{{\eta }_A}{{\eta }_A+{\eta }_B}{P}_B=P_B^{\circ }\times \frac{{\eta }_B}{{\eta }_A+{\eta }_B}$