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 of a solution made from dissolving 10.7 g of biphenyl in 33.9 g of benzene?
moles biphenyl = grams/molar mass
moles benzene = grams/molar mass
mol fraction benzene = Xbenzene = mol benzene/total moles.
partial pressure benzene = Xbenzene*Pnormal v.p.
I did what you said and didn't get the correct answer :(
Post your work and I'll try to find your error.
Can someone confirm the answer for this. I worked it out and got an answer of 85.5 torr. Is this right? Can someone please put the answer to this so I can check. Thanks. That would be helpful.
I worked it and obtained 86.9 torr which is close to your number but not quite the same. I used 154 for the molar mass of biphenyl and I used 78 for the molar mass of benzene.
If you will post your work I'll look at it. Please make a new post of it--this one is getting a little far from the front page.
To determine the vapor pressure of the solution, we can use Raoult's law. Raoult's law states that the vapor pressure of a solution is equal to the mole fraction of the solvent multiplied by the vapor pressure of the pure solvent. The equation can be written as follows:
P_solution = X_solvent * P_solvent
First, we need to calculate the mole fraction of benzene in the solution. The mole fraction (X) is the ratio of moles of benzene to the total moles of both solute and solvent. We can calculate moles using the equation:
moles = mass / molar mass
For benzene:
moles of benzene = 33.9 g / 78.11 g/mol
Next, we calculate the mole fraction:
X_benzene = moles of benzene / (moles of biphenyl + moles of benzene)
Now, we need to calculate the vapor pressure of benzene in the solution. We already know that the vapor pressure of pure benzene is 100.84 torr.
Finally, we can determine the vapor pressure of the solution by substituting the values into the Raoult's law equation:
P_solution = X_benzene * P_benzene
Calculating each component and substituting the values into the equation, we can determine the vapor pressure of the solution.