A solution is made by dissolving 26.7 g urea, a nonelectrolyte, in 301 g water. (The vapor pressure of pure water is 23.8 torr at 25°C and 71.9 torr at 45°C.)

Calculate the vapor pressure of this solution at 25°C.

mols urea = grams/molar mass = ?

mols H2O = grams/molar mass = ?
Total mols = sum

mol fraction = XH2O = mos H2O/total mols
pH2O = XH2O*PoH2O.
If you want it at 25 C, use Po at 25 C.

To calculate the vapor pressure of the solution at 25°C, we can use Raoult's law, which states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent present.

The first step is to calculate the mole fraction of water in the solution. The mole fraction (X) is calculated by dividing the moles of water by the total moles of water and urea.

To calculate the moles of water, we need to know the molar mass of water. The molar mass of water is 18.015 g/mol.

Moles of water = mass of water / molar mass of water

Given: mass of water = 301 g
molar mass of water = 18.015 g/mol

Moles of water = 301 g / 18.015 g/mol ≈ 16.7 mol

Next, calculate the moles of urea. The molar mass of urea is 60.06 g/mol.

Moles of urea = mass of urea / molar mass of urea

Given: mass of urea = 26.7 g
molar mass of urea = 60.06 g/mol

Moles of urea = 26.7 g / 60.06 g/mol ≈ 0.445 mol

Now, calculate the mole fraction of water.

Mole fraction of water (X) = moles of water / (moles of water + moles of urea)

Mole fraction of water = 16.7 mol / (16.7 mol + 0.445 mol) ≈ 0.974

Since urea is a nonelectrolyte, it does not dissociate into ions in solution, so the mole fraction of urea can be approximated as 1 - mole fraction of water.

Mole fraction of urea = 1 - mole fraction of water
Mole fraction of urea ≈ 1 - 0.974 ≈ 0.026

According to Raoult's law, the vapor pressure of the solution is equal to the mole fraction of water times the vapor pressure of pure water.

Vapor pressure of the solution = mole fraction of water * vapor pressure of pure water

Given: vapor pressure of pure water at 25°C = 23.8 torr

Vapor pressure of the solution = 0.974 * 23.8 torr ≈ 23.19 torr

Therefore, the vapor pressure of the solution at 25°C is approximately 23.19 torr.