Question

3.795 g of sulphur is dissolved in 100 g of CS₂. This solution boils at 319.81 K. What is the molecular formula of sulphur in solution? The boiling point of CS₂ is 319.45 K. (Given that K_b for CS₂ = 2.42 K kg mol^-1 and atomic mass of S = 32.)

Answer 1

Given : 

W₂ = 3.795 g; 

W₁ = 100 g CS₂ 

T_b = 319.81 K; 

T₀ = 319.45 K 

K_b = 2.42 K kg mol^-1 

M₂ = ? 

ΔT_b = T_b – T₀ 

= 319.81 – 319.45 

= 0.36 K

Number of S atoms in molecule = \(\frac{255.1}{32}\)

= 7.972

≅ 8

∴ Formula of sulphur in CS₂ solution = S₈