Question

How long (approximate) should water be electrolysed by passing through $100$ amperes current so that the oxygen released can completely burn $27.66g$ of diborane ? (Atomic weight of $B=10.8u$ )

• A. 6.4 hours
• B. 0.8 hours
• C. 3.2 hours
• D. 1.6 hours

Answer 1

Answer: (C)

$B_2{H}_6+3O_2⟶B_2{O}_3+3H_{2}O$

$27.66$ of $B_2{H}_6=1$ mole of $B_2{H}_6$ which requires three moles of oxygen $\left(O_2\right)$ for complete burning

$6H_{2}O⟶6H_2+3O_2$ (On electrolysis)

Number of faradays $=12=$ Amount of charge

$12\times 96500=i\times t$

$12\times 96500=100\times t$

$t=\frac{12\times 96500}{100}$ second

$t=\frac{12\times 96500}{100\times 3600}$ hour

$t=3.2$ hours