Question

An aqueous solution containing $1M$ each of $A{u}^{3+}$ , $C{u}^{2+}$ , $A{g}^{+}$ , $L{i}^{+}$ is being electrolyzed by using inert electrodes. The value of standard potentials are
$E_{A{g}^{+}/Ag}^{{}^{\circ }}=0.80V,E_{C{u}^{+}/Cu}^{{}^{\circ }}=0.34V,$ $E_{A{u}^{3+}/Au}^{{}^{\circ }}=1.50V,E_{L{i}^{+}/Li}^{{}^{\circ }}=-3.03V$
With increasing voltage, the sequence of deposition of metals on the cathode will be

• A. $Li,Cu,Ag,Au$
• B. $Cu,Ag,Au$
• C. $Au,Ag,Cu$
• D. $Au,Ag,Cu,Li$

Answer 1

Answer: (C)

The most unreactive metal that the ion which has the most positive reduction potential will be released to first. Further $L{i}^{+}$ has a very negative reduction potential hence it will not be released in aqueous medium.