Question

The mol fraction of benzene in a solution in Toluene is 0.50. calculate the weight percent of benzene in solution.

Answer 1

Let, mole fraction of benzene is X1 and that of toluene is X2

We know that, in a solution X1 + X2 =1

As X1 = 0.1 so mole fraction of toluene will be 0.5

So, each mole of the solution will have 0.5 moles of benzene and 0.5 moles of toluene.

Now, we have, 1 mole of benzene (C6H6) = 78 gm

so, 0.5 mole of benzene = 78 x 0.5 = 39 gm

Similarly 0.5 moles of toluene (C6H5CH3) will be = 92 x 0.5 =46 gm

Now we know that weight % = mass of component / total mass of solution x 100

Hence weight %age of benzene = 39/ (39 + 46) x100 = 39/85 x 100 = 45.88 %