Chemistry - Liquid Solution Question with Solution | TestHub

$$\Delta T_f=K_f\times M\times \frac{W_w\times 1000}{M_{solute}\times W_{solvent}}$$

For XY₂:

$$2.3=5.1\times \frac{1\times 1000}{M_{X{Y}_2}\times 20}$$

$$M_{X{Y}_2}=\frac{5100}{46}=110.87$$

For XY₄:

$$1.3=5.1\times \frac{1000}{M_{X{Y}_4}\times 20}$$

$$M_{X{Y}_4}=\frac{5100}{26}=196.15$$

Let the atomic mass of X be $x$ and Y be $y$.

$$x+2y=110.87$$

$$x+4y=196.15$$

Subtracting the first equation from the second:

$$2y=196.15-110.87=85.28$$

$$y=\frac{85.28}{2}=42.64$$

Therefore, the atomic mass of Y is $42.64$.