Question 1
The vapour pressures of ethanol and propanol are 17000Pa and 15450Pa respectively. An ideal solution is formed by mixing 24g of ethanol with 35g of propanol. Calculate the vapour pressure of each component and thus the mole fraction of the two components in the vapour phase.
ethanol: 0..496, propanol: 0.504 Working
Question 2
What is the vapour pressure at 298K of a 20% solution of KNO3 by mass. Vapour pressure of water at 298K is 3.2kPa.
Answer: 3.37kPa (Working)
Question 3
At a given temperature, the vapour pressure of heptane is 1500 Pa and that of octane is 860 Pa. Assuming ideal behaviour, and that the vapour contains 3 times as many moles of octane as heptane, what is the mole fraction of the heptane in the liquid phase?
Answer: mfheptane = 0.160 (Working)
Question 4
What is the vapor pressure when 56.7 g of CuSO4 are added to 700 mL of H2O at 330K.
The vapor pressure of pure H2O at 330K is 14kPa
The density of H2O at 330K is 1.00 g/mL.
Answer: 13.92kPa (Working)
Question 5
Aspirin is very soluble in ether. If 0.372g of aspirin are dissolved in 2.97g of diethyl ether, the vapor pressure of the ether lowers from 0.631 to 0.601 atm at 23oC. What is the molecular weight of the aspirin?
RMM aspirin = 150.1g (Working)
Question 6
The vapour pressure of an aqueous solution of glucose at 373K is 0.96 atm. Calculate the molarity of the solution.
Concentration: 1.852 mol dm-3 (Working)
Question 7
A solution is prepared by mixing 30.0 mL of butane (C4H10, d = 0.600 g/mL) with 65.0 mL of octane (C8H18, d = 0.700 g/mL). Assuming the volumes add in mixing, calculate the mass percentage of butane in the vapour phase.
Question 8
A solution contains A and B. If their vapour pressure is 1.6atm and 0.6 atm respectively, and the mole fraction in the vapour phase is equimolar, what is the mole fraction of A in the liquid phase?
Harder Question
Question 9
The vapour pressure of benzene is 1.1atm whilst the vapour pressure of toluene is 0.7atm.
What is the % by mass of benzene in the vapour phase if the total pressure is 0.83atm.
Question 10
A mixture of benzene (Vapour Pressure 1.1 atm) and toluene (Vapour Pressure 0.7 atm) is prepared. The mole fraction of benzene in the vapour phase is 0.65. Assuming ideal behaviour, calculate the mole fraction of toluene in the liquid phase.
Question 11
At 298K, methanol has a vapor pressure of 16.9kPa and ethanol has a vapor pressure of 7.83kPa. If the vapour pressure of methanol above the mixture is 0.35, calculate the mole fraction of ethanol in the mixture.
Answer: 0.800 (Working)