Exercise 10 | Colligative Properties of Solutions

Henry’s Law:

Solubility of a gas is proportional to the pressure of the gas
 

Let’s determine the Henry’s law constant for dioxygen:

k = $\frac{{\mathrm{P}}_{\mathrm{O}2}}{M_{O2}}$

P_O2 = 750 mmHg = 0.987 atm

⇒ k = 7.65 x 10²

Solubility of dioxygen gas at 25°C and a pressure of 1150 mmHg:

M_O2 = $\frac{{\mathrm{P}}_{\mathrm{O}2}}{\mathrm{k}}$

P_O2 = 1150 mmHg = 1.513 atm

⇒ M_O2 = $\frac{1.513}{7.65 \times {10}^2}$ = 1.97 x 10^-3 mol.L^-1

Solubility (in g.mL^-1) = M_O2 (in mol.mL^-1) x M_O2 (in g.mol^-1) = 1.97 x 10^-6 x 32.0 = 6.33 x 10^-5 g.mL^-1