Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 °C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure (in torr) of a solution made from dissolving 16.6 g of biphenyl in 26.0 g of benzene?

vapor pressure is dependent on the mole ratios.

vapor pressusre=100.84*Molebenzene/total moles

moles benzene=26/molmassBenzene

moles biphenyl=16.6/molmassBiphenyl

total moles add those two.

To find the vapor pressure of a solution made by dissolving biphenyl in benzene, we need to apply Raoult's Law, which states that the vapor pressure of a solvent above a solution is directly proportional to the mole fraction of the solvent in the solution.

1. Convert the given masses of biphenyl and benzene to moles.
- Biphenyl (C12H10):
- Mass = 16.6 g
- Molar mass = 12*12.01 g/mol (carbon) + 10*1.01 g/mol (hydrogen)
- Moles = 16.6 g / molar mass of biphenyl

- Benzene (C6H6):
- Mass = 26.0 g
- Molar mass = 6*12.01 g/mol (carbon) + 6*1.01 g/mol (hydrogen)
- Moles = 26.0 g / molar mass of benzene

2. Calculate the mole fraction of benzene (solvent) in the solution.
- Mole fraction of benzene = moles of benzene / (moles of biphenyl + moles of benzene)

3. Calculate the vapor pressure of the solution using Raoult's Law.
- Vapor pressure of the solution = mole fraction of benzene * vapor pressure of benzene.

Let's calculate the values step by step.

1. Moles of biphenyl:
- Molar mass of biphenyl = (12 * 12.01) + (10 * 1.01) = 154.23 g/mol
- Moles = 16.6 g / 154.23 g/mol

2. Moles of benzene:
- Molar mass of benzene = (6 * 12.01) + (6 * 1.01) = 78.11 g/mol
- Moles = 26.0 g / 78.11 g/mol

3. Mole fraction of benzene:
- Mole fraction of benzene = moles of benzene / (moles of biphenyl + moles of benzene)

4. Vapor pressure of the solution:
- Vapor pressure of the solution = mole fraction of benzene * vapor pressure of benzene

Using the given vapor pressure of pure benzene at 25 °C (100.84 torr), we can substitute the values and calculate the vapor pressure of the solution.