Question

A sample of sulfur weighing 0.210 g was dissolved in 17.8 g of carbon disulfide, CS2 (K_b = 2.43 °C/m). If the boiling point elevation was 0.107 °C, what is the molecular weight of a sulfur molecule in Carbon Disulfide?

Answer 1

$\Delta\>T_b=k_b×M$

$0.107=2.73×M$

$M=4 .4033×10^{-2}$

Amount of the sample in 1kg of $CS_2$

$=\frac{1000}{17.8}×0.210$

$=11.7978g$

Molecular weight of the sulphur sample

$=\frac{1}{4.4033×10^{-2}}×11.7978$

$=267.9g$