Question
What volume of hydrogen gas, at $${\text{273}}K$$ and 1 atm. pressure will be consumed in obtaining $$21.6\,g$$ of elemental boron $$\left( {{\text{atomic}}\,{\text{mass = 10}}{\text{.8}}} \right)$$ from the reduction of boron trichloride by hydrogen ?
A.
$$67.2L$$
B.
$$44.8L$$
C.
$$22.4L$$
D.
$$89.6L$$
Answer :
$$67.2L$$
Solution :
$$\eqalign{
& 2BC{l_3} + 3{H_2} \to 2B\, + \,6HCl \cr
& or\,BC{l_3} + \frac{3}{2}{H_2} \to B + 3HCl \cr
& {\text{Now,}}\,{\text{since}}\,{\text{10}}{\text{.8}}\,gm\,{\text{boron}}\,{\text{requires}}\,{\text{hydrogen}} \cr
& {\text{ = }}\frac{3}{2} \times 22.4L\,at\,N.T.P \cr
& {\text{hence}}\,{\text{21}}{\text{.6}}\,gm\,{\text{boron}}\,{\text{requires}}\,{\text{hydrogen}} \cr
& \frac{3}{2} \times \frac{{22.4}}{{10.8}} \times 21.6 = 67.2L\,{\text{at}}\,N.T.P. \cr} $$