A solution contains 5.00 g of urea, CO(NH2)2 (a nonvolatile solute) and 0.100 kg of water. If the vapor
pressure of pure water at 25 °C is 23.7 torr, what is the vapor pressure of the solution assuming ideal
behavior?
How many moles urea? That's moles = g/molar mass.
moles urea = 5.00/molar mass urea = ?
moles H2O = 1000 g/molar mass H2O = ?
Total mols = mols urea + moles water = ?
moled fraction water XH2O = ?
Psolution = XH2O*PoH2O
Substitute and solve. Post your work if you get stuck.
oops. Left out a step.
To get XH2O it is mols H2O/total moles = ?
To find the vapor pressure of the solution, we need to use Raoult's law, which states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent.
First, let's calculate the mole fraction of the water in the solution.
Moles of water = mass of water / molar mass of water
Moles of water = 0.100 kg / 18.015 g/mol
Moles of water = 5.549 mol
Mole fraction of water = moles of water / total moles of solute and solvent
Mole fraction of water = 5.549 mol / (5.549 mol + 0.100 mol)
Mole fraction of water ≈ 0.982
Next, we can use Raoult's law to find the vapor pressure of the solution.
Vapor pressure of the solution = mole fraction of water * vapor pressure of pure water
Vapor pressure of the solution = 0.982 * 23.7 torr
Vapor pressure of the solution ≈ 23.28 torr
Therefore, the vapor pressure of the solution is approximately 23.28 torr assuming ideal behavior.