Question

Which of the following redox reactions do you expect to occur spontaneously in the forward direction under standard conditions?

a. Ni(s)+Zn2+(aq)→Ni2+(aq)+Zn(s)
b. Pb(s)+Mn2+(aq)→Pb2+(aq)+Mn(s)
c. Ni(s)+Pb2+(aq)→Ni2+(aq)+Pb(s)
d. Cr(s)+3Ag+(aq)→Cr3+(aq)+3Ag(s)
e. None of the above

Answer 1

Recalling the chapter on thermodynamics, the spontaneities of the forward and reverse reactions of a reversible process show a reciprocal relationship. The spontaneous oxidation of copper by lead(II) ions is not observed, while the oxidation of lead by copper(II) ions is predicted to occur spontaneously.

Step-by-step explanation:

Recalling the chapter on thermodynamics, the spontaneities of the forward and reverse reactions of a reversible process show a reciprocal relationship: if a process is spontaneous in one direction, it is non-spontaneous in the opposite direction. As an indicator of spontaneity for redox reactions, the potential of a cell reaction shows a consequential relationship in its arithmetic sign. The spontaneous oxidation of copper by lead(II) ions is not observed,

Cu²+ (aq) + Pb(s) → Cu(s) + Pb²+ (non-spontaneous)

and so the reverse reaction, the oxidation of lead by copper(II) ions, is predicted to occur spontaneously:

Pb(s) + Cu²+ (aq) → Pb²+ (aq) + Cu(s) (spontaneous)