Question

The mole fraction of benzene in a solution in toluene is 0.50. Calculate the weight per cent of benzene in the solution.

Answer 1

Explanation:

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 = 41.88 %