Example Questions based on Mole Fraction Formula
Find the mole fraction of Methanol CH3
OH and water in a solution prepared by dissolving 4.5 g of alcohol in 40 g of H2
Molar Mass of H2
O is 18gm/mole and Molar mass of CH3
OH is 32gm/mole
Moles of CH3
OH = 4.5 / 32 = 0.14 mole
Moles of H2
O = 40 / 18 = 2.2 moles
Therefore, according to the equation
Mole fraction of CH3
OH = 0.14 / 2.2 + 0.14
Mole fraction of H2
O. = 2.2 / 2.2 + 0.14
Calculate the mole fraction of HCl and H2
O in a solution of hydrochloric acid in water, containing 30% HCl by weight.
The solution contains 30 grams of Hydrochloric acid and 70 grams of water. Also,
of HCl is 36.5 grams/mole.
Molar mass of water is 18 grams/mole.
Moles of HCl = 30/36.5 = .821 moles of HCl
Moles of water = 70/18 = 3.88 moles of H2O.
Mole fraction of HCl = .821/(.821 + 3.88) = .174
Mole fraction of H2O = 3.88/(.821 + 3.88) = .825
In a solution , we have 1 mole ofA , 1 mole ofB and 2 mole of C. Find the mole fraction of each of them
This is an extension of two component solution which we discussed above
Mole fraction will be defined as
χA = nA / (nA + nB + nC ) = 1/(1+1+2) =.25
χB = nB / (nA + nB + nC ) = 1/(1+1+2) =.25
χC = nC / (nA + nB + nC ) = 2/(1+1+2) =.5
χA + χB + χC =1