Question

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

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

Answer 1

Answer: (C)

3.2 hours

Answer 2

$B _{2} H _{6}+3 O _{2} \longrightarrow B _{2} O _{3}+3 H _{2} O$
$27.66$ 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

$6 H _{2} O \longrightarrow 6 H _{2}+3 O _{2}$ (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