Question

Calculate the mole fraction of ethanol and water in a sample of rectified spirit which contains 46% ethanol by mass

Answer 1

Answer:

the question states that the solution has 92% ethanol by mass

so if the solutions weighs 100gms , it contains 92gms of ethanol and 8gms of water

no.of moles of ethanol = weight of ethanol / molecular weight of ethanol

molecular weight of ethanol is 46

no. of moles of ethanol is 92/46 i.e 2

no.of moles of water is 8/18 i.e 0.222

mole fraction of ethanol = no.of moles of ethanol / total number of moles

= 2/2.222

=0.90 (approx)

mole fraction of water =1-mole fraction of ethanol

=1-0.9

=0.1 (approx)