Question

A) The solubility of neon gas in water at 25°C is 1.05x10-3 M when the pressure of the Ne above the solution is 1.0 atm. the solubility of Ne (g) is?
B) the vapor pressure of pure ethanol at 60°C is 0.459 atm. Raoult's law predicts that a solution prepared by dissolving 10.0 mmol naphthalene in 90.0 mmol ethanol will have a vapor pressure of?

Answer 1

Solution.

A) To convert the solubility from mol/L to g/L let's suppose that we have 1 L of solution. In this case, the amount of Ne is 1.05x10^-3 mol; 1 mol of Ne weights 20.18 g, therefore we have 20.18*1.05x10^-3 = 0.021 g. The solubility of Ne is 0.021 g/L.

B) According to the Raoult's Law, the partial vapor pressure of a component in a mixture is equal to the vapor pressure of the pure component at that temperature multiplied by its mole fraction in the mixture.The molar fraction of ethanol in this solution is 90.0/(10.0+90.0) = 0.9.

Therefore, the vapor pressure of this solution will be 0.9*0.459 = 0.413 atm.