Question

Calculate the mole fractio of ethanol in a sample of spirit containing 92% ethanol by mass.

Answer 1

`x_(C_(2)H_(5)OH)=(n_(C_(2)H_(5)OH))/(n_(C_(2)H_(5)OH)+n_(H_(2)O)`
Mass of `C_(2)H_(5)OH=92g,Molar mass of C_(2)H_(5)OH=46g mol^(-1)`
`C_(2)H_(5)OH=((92g))/((46gmol^(-1))=2 mol)`
Mass of `H_(2)O=8g, Molar mass of H_(2)O=189g mol ^(-1), n_(H_(2)O)=((8g))/((18gmol^(-1))=0.44 mol`
`x_(C_(2)H_(5)OH)=((2 mol))/((2mol)+(0.44mol))=0.82`