Q. What volume of hydrogen gas, at 273 K and 1 atm pressure will be consumed in obtaining 21.6 g of elemental boron (atomic mass = 10.8) from the reduction of boron trichloride by hydrogen?
A) 89.6 L
B) 67.2 L
C) 44.8 L
D) 22.4 L
Explanation
(b)
$2BCl_{3} + 3H_{2} \rightarrow 2B + 6HCl\$
2 mol 3 mol 2 mol
21.6 g=2 mol
21.6 g B= 2 mol B$\equiv$ 3 mol $H_{2}$
$pV = nRT$
$\therefore V = \frac{nRT}{P} = \frac{3 \times 0.0821 \times 273}{1} = 67.2\ L$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.