Question

The solubility constant for CO2 in water at 25 celsius is 3.40 x 10-2 M/atm. The solubility of CO2 is 35.158 mM in water that is exposed to a gas mixture in which the mole fraction of CO2 is 0.67. What is the total pressure of this gas mixture? Express your answer in units of atmospheres using at least three significant figures.

Answer 1

Solubility constant (K_h) = 3.40 x 10^-2 M/atm

Solubility of CO₂ = 35.158 x 10^-3 M

Calculate partial pressure of CO₂ from Henry's law:

Solubility = K_h * partial pressure

35.158 x 10^-3 M = (3.40 x 10^-2 M/atm) x partial pressure

Partial pressure = (35.158 x 10^-3 M) / (3.40 x 10^-2 M/atm)

= 1.034 atm

Now, partial pressure of CO₂ = mole fraction * total pressure

1.034 atm = 0.67 * total pressure

Total pressure = 1.034 atm/0.67 = 1.543 atm

Answer: Total pressure of gas mixture is 1.54 atm.