Ncert Exercises & Solutions

2.1 Calculate the mass percentage of benzene (C₆H₆) and carbon tetrachloride (CCl₄) if 22 g of benzene is dissolved in 122 g of carbon tetrachloride.

Mass percentage of C₆H₆ $= \frac{Mass of C_{6} H_{6}}{Total mass of the solution} \times 100$

$= \frac{Mass of C_{6} H_{6}}{Mass of C_{6} H_{6} + Mass of {CCl}_{4}} \times 100$
$= \frac{22}{22 + 122} \times 100$
$= 15.28 %$

Mass percentage of CCl₄ $= \frac{Mass of {CCl}_{4}}{Total mass of the solution} \times 100$
$= \frac{122}{22 + 122} \times 100$
$= 84.72 %$

Alternatively,

Mass percentage of CCl₄ = (100 − 15.28)% = 84.72%