Density of pure ethyl alcohol is 0.785gcm−3.The density of its solution in water (10% by volume ) is 0.98668 cm3.Calculate the percentage by weight of the solution.

(i) Volume of ethyl alcohol 10 cm3 ; Density =0.785gcm−1∴ Weight of ethyl alcohol = Vol. x Density=10cm3×0.785gcm−3= 7085 g(ii) volume of solution =100cm3 ;Density =0.9866gcm−3∴ Weight of solution = Vol. x Density =100cm3×0.9866gcm−3= 98.66 g Hence, percent by weight = Wt.of ethylalcohol  Wt.of solution ×100=7.8598.66×100=7.95%