Question

Calculate the mole fraction of ethyl acetate, in a toluene-ethyl acetate mixture if you mix 1 mL of ethyl acetate and 1 mL of toluene. The density of ethyl acetate (C4H8O2) is 0.898 g/mL; the density of toluene (C7H8) is 0.867 g/mL.

Answer 1

First you need the molar mass (MM) of each chemical in the mixture:
MM of ethyl acetate - 88.105g/mol
MM of Toluene - 92.14g/mol

No of moles = Mass/ Molar Mass
Mass = Volume x Density

Mass of ethyl acetate = 1ml x 0.898g/ml = 0.898g
Mass of Toluene = 1ml x 0.867 = 0.867g

Therefore, No. of moles of ethyl acetate in mixture = 0.898g / 88.105g/mol = 0.010192mol
and No of moles of toluene in mixture = 0.867g / 92.14g/mol = 0.00941

Total number of moles in this mixture = 0.010192 + 0.00941 = 0.019602 moles

Therefore the mole fraction of ethyl acetate in the mixture is = No of moles of ethy acetate / Total number of moles in mixture

Answer = 0.010192 / 0.019602 = 0.5199

expressed as percentage = 0.5199 x 100% = 51.99%