To calculate the vapor pressure of the solution, we can use the formula:
P_solution = P_water * X_water
Where P_solution is the vapor pressure of the solution, P_water is the vapor pressure of pure water, and X_water is the mole fraction of water in the solution.
First, let's calculate the number of moles of each component in the solution, which involves finding the molar mass of urea.
Urea (NH2)2CO has the following molecular composition: 1 Carbon, 4 Hydrogen, 2 Nitrogen, and 1 Oxygen.
C: 12.01 g/mol
H: 1.01 g/mol
N: 14.01 g/mol
O: 16.00 g/mol
Molar mass of urea = (1 × 12.01) + (4 × 1.01) + (2 × 14.01) + (16.00)
= 12.01 + 4.04 + 28.02 + 16.00
= 60.07 g/mol
Now, we can calculate the number of moles of urea and water in the solution.
Moles of urea = mass (g) / molar mass (g/mol) = 35.0 g / 60.07 g/mol = 0.582 moles
Moles of water = mass (g) / molar mass (g/mol) = 75.0 g / 18.02 g/mol = 4.16 moles
Next, we can find the mole fraction of water in the solution.
X_water = moles of water / (moles of water + moles of urea) = 4.16 / (4.16 + 0.582) = 4.16 / 4.742 = 0.877
Now, we can use the formula to find the vapor pressure of the solution.
P_solution = P_water * X_water
= 23.8 torr * 0.877
= 20.87 torr
Thus, the vapor pressure of the solution is approximately 20.87 torr at 25°C.
The vapor pressure of water at 25 oC is 23.8 torr. Calculate the vapor pressure of a solution prepared by dissolving 35.0 g of urea [(NH2)2CO] in 75.0 g of water at 25 oC.
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