The relative decrease in vapour pressure of an aqueous solution is observed to be (approx. ). How ma — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

RLVP $= \frac{i \times n}{i \times n + N}$. $NaCl$ yields $i=2$. Moles of water $N = 180/18 = 10$. Thus, $0.167 \approx 1/6 = \frac{2n}{2n + 10}$. Cross multiplying: $6(2n) = 2n + 10 \implies 12n = 2n + 10 \implies 10n = 10 \implies n = 1\text{ mole}$.