Question

A galvanic cell is set up from a zinc bar weighing $100g$ and $1.0$ litre of $1.0MCu$SO_4$solution.Howlongwouldthecellrunifitisassumedtodeliverasteadycurrentof$1.0$ampere?(Atomicmassof$Zn = 65$)

• A. 1.1 hr
• B. 46 hr
• C. 53.6 hr
• D. 24.00 hr

Answer 1

Answer: (C)

$100g$ of $Zn=\frac{100}{65}$ mol. Thus, according to reaction,
$Zn+C{u}^{2+}\to Z{n}^{2+}+Cu,C{u}^{2+}$ ions are limiting reagents.
Now, charge flowing for reduction of $1$ mole of $C{u}^{2+}$ ions
$=2\times 96500C$
If $1$ ampere of current is to be delivered for $t$ hours,
the quantity of electricity is $3600tC$.
Now $3600t=2\times 96500$
$t=\frac{2\times 96500}{3600}=53.61hr$