1. Tardigrade
  2. Question
  3. Chemistry
  4. The vapour pressure of two liquids 'P' and 'Q' are 80 and 60 torr respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mol of Q would be

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Q. The vapour pressure of two liquids $'P'$ and $'Q'$ are $80$ and $60$ torr respectively. The total vapour pressure of solution obtained by mixing $3$ mole of $P$ and $2$ mol of $Q$ would be

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Solution:

Mole fraction of $P=\frac{3}{3+2}=\frac{3}{5}$
Mole fraction of $Q=\frac{2}{3+2}=\frac{2}{5}$
Hence, total vapour pressure $=$ (Mole fraction of $P \times$ Vapour pressure of $P)+($ mole fraction of $Q \times$ Vapour pressure of $Q)$
$=\left(\frac{3}{5} \times 80+\frac{2}{5} \times 60\right)=48+24$
$=72$ torr