Question

mole fraction of ethanol-water system is 0.25. what is the percent concentration of ethanol by weight the solution.

Answer 1

Given that the mole fraction of ethanol-water system is 0.25

i.e. solution contains 0.25 mol EtOH and 0.75 mol H₂O

Mol wt of EtOH is 46.06 g/mol Therefore 0.25 mol = 11.515 g of EtOH

Mol wt of H₂O is 18.01528 g/mol There fore 0.75 mol = 13.51 g of H₂O

Total weight = 25.02646 gms

Wt % of EtOH is 11.515 / 25.02646 x 100 = 46.011 %