Practice question
Question
A gas has a Henry’s law constant of 350 bar at 25°C. If 0.02 mole of the gas is dissolved in 800 g of water at 7 bar, what is the molality of the solution?
Explanation
Molality = (moles/mass of solvent in kg) = (0.02/0.8) = 0.025 mol/kg . Cross-check: x = (7/350) = 0.02 , slightly off due to approximation, but molality is direct.