Answer:
The vapor pressure of the solution is 23.3 torr
Explanation:
Step 1: Data given
Mass of urea = 5.25 grams
Mass of water = 0.100 kg = 100 grams
Temperature = 25.0 °C
Vapor pressure of water = 23.7 torr
Step 2: Calculate moles of water
Moles H2O = mass H2O / molar mass H2O
Moles H2O = 100 grams / 18.02 g/mol
Moles H2O = 5.55 moles
Step 3: Calculate moles of urea
Moles urea = 5.25 grams / 60.06 g/mol
Moles urea = 0.0874 moles
Step 4: Calculate mol fraction H2O
Mol fraction H2O = 5.55 moles / (5.55 + 0.0874)moles
Mol fraction H2O = 0.984
Step 5: calculate the vapor pressure of the solution
This means that you can use the mole fraction of water and the vapor pressure of pure water at 25°
C to determine the vapor pressure of the solution.
Psol =Xwater * Pwater
⇒Psol = the vapor pressure of the solution
⇒Xwater =the mol fraction of water
⇒Pwater = the vapor pressure of pure water
Psol = 0.984 * 23.7 torr
Psol = 23.3 torr
The vapor pressure of the solution is 23.3 torr
