Question

Use the standard half-cell potentials listed below to determine which the following metals will dissolve in hydrochloric acid. Cl2(g) + 2e -- 2014(aq); E° = 1.36 V 2H+(aq) + 2e - H2(g); E° = 0.00 V OPt; E°(P+2+/Pt) = +1.19V O Ag; E°(Ag+/Ag) = +0.80V O Au; EⓇ(Au3+/Au) = +1.50V O Al; E(A13+/Al) = -1.66V O Cu; E(Cu2+/Cu) = +0.34V

Answer 1

We know from the fact of electrochemical series that, more positive half-cell potential, stronger Oxidising agent the metal ion is! That means as the electrode potential becomes more positive, the metal ion tends to get reduced more readily.

Now, to get dissolved into HCl, we would only consider the $E^{0}$ value of $H^{+}$ ions as the chloride ions are spectator ions here. Now, only the has less $E^{0}$ value than the $H^{+}$ ions. This means only can reduce the
H /H
system and get itself oxidized to $Al^{3+}$ ions and come to the solution (means get dissolved!)-

These are the species we are starting with This is more negative, so the equilibrium moves to the LEFT AL30 + 3 = Ales) Eº = -1.66V) Coq) 210 20 = H2 cq] E° = 0.00 V coqy This is more positive, so the equilibrium moves to RIGHT

Hence, only Al will get dissolved in HCl.

Option IV is correct.