If an ideal solution contains 3.50 mol of a non-volatile solute and 15.8 mol of solvent, and it has a vapor pressure of 22.6 torr, what is the vapor pressure of the pure solvent (in torr)

The vapor pressure of the solution is 18.5 torr

Explanation:

As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The formula for relative lowering of vapor pressure will be,

where,

= relative lowering in vapor pressure

i = Van'T Hoff factor = 1 (for non electrolytes)

= mole fraction of solute

Given :  moles of solute = 3.50

moles of solvent = 15.8

Total moles = moles of solute  + moles of solvent = 3.50 + 15.8 = 19.3

= mole fraction of solute =

Thus the vapor pressure of the solution is 18.5 torr

the answers would be

the first one and the second one