Question

The weight of glucose dissolved in $100gm$ of water produce same lowering of vapour pressure as $1\,gm$ urea dissolved in $50\,gm$ of water at same temperature is

Answer 1

Since same lowering in vapour pressure. Mole fractions of solutes should be equal.
$ X _{\text {urea }}= X _{\text {glucose }}$
$\frac{\frac{1}{60}}{\frac{1}{60}+\frac{50}{18}}=\frac{\frac{w}{180}}{\frac{w}{180}+\frac{100}{18}}$
$\Rightarrow \frac{\frac{1}{60}}{\frac{50}{18}}=\frac{\frac{w}{180}}{\frac{100}{18}}$
For dilute solution $\Rightarrow w =6\,$ gm of glucose