9 Safrole is used as a topical antiseptic Calculate the vapo

9. Safrole is used as a topical antiseptic. Calculate the vapor pressure of a solution prepared by dissolving

0.75 mol of safrole in 950 g of ethanol (46.07 g/mol). P

Solution

No . of moles of ethanol , n = mass / Molar mass
= 950 g / 46.07 g / mol
= 20.62 mol
No . of moles of safrole , n\' = 0.75 mol
Total no . of moles , N = n + n\' = 21.37 mol
Mole fraction of safrole , X = n\' / N
= 0.0351
According to Raoult\'s law
relative lowering of vapour pressure = mole fraction of solute
( po - p ) / po = X
Where po = vapour pressure of pure ethanol = 50.0 torr
p = vapour pressure of the solution = ?
Plug the values we get ( 50 - p ) / 50 = 0.0351
50 - p = 1.755
p = 48.2 torr