I don't know how to calculate the number of moles from the mole fraction.
This is the problem: What is the concentration of solute in an aqueous solution whose vapor pressure , at 20 degree Celsius, is 17.0 mm Hg? the vapor pressure of water, at 20 degree Celsius, is 17.4 mm Hg.
I used this formula: deltaP = xPsolvent; x is the mole fraction of solute. I calculated the x and from there I don't know how to solve the number of moles of the solute, since I don't know the number of moles of water.
Thank you for anyone who can help.