a) Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 degrees Celcius, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 13.8 g of biphenyl in 32 g of benzene?

Question

b) Express the concentration of a 0.07 M aqueous solution in fluoride, F^-, in mass parts per million. Assume the density of the solution is 1.00 g/mL.

Answer 1

Note the correct spelling of celsius.
psoln = Xbenzene*Pobenzene

You need Xbenzene. Get that from
nbiphenyl = grams/molar mass = ?
nbenzene = grams/molar mass = ?

Xbenzene = nbenzene/total mols.
Then substitute Xbenzene in first equation above and solve for p solution.