Question

The volume (in litres) of hydrogen gas at $273$ K and $1$ atm pressure that will be consumed in obtaining $21.6$ g of elemental boron (atomic mass $=10.8$ amu) from reduction of boron trichloride by hydrogen gas is : (as nearest integer)

Answer 1

The reduction reaction of boron trichloride by hydrogen is as follows:

$2BC{l}_3+3H_2\to 2B+6HCl$

Mass of $2$ moles of $B=10.8\times 2=21.6$ g

According to equation given above:

$3$ moles of $H_2$ gas at STP reacts with $BC{l}_3$ to give $21.6$ g of boron.

Now, $1$ mole of $H_2$ at STP occupies a volume of $22.4$ L.

Therefore, $3$ moles will occupy $=22.4\times 3=67.2$ L

Hence, the volume consumed is $67.2$ L.

The answer in the nearest integer is $67$.