Question

Which of the following represents the balanced reduction half-reaction from the redox reaction? (2 points)

Pb + Pd(NO3)2 yields Pb(NO3)2 + Pd


Pb yields Pd2+ + e-

Pd2+ + 2e- yields Pd

Pb + e- yields Pb

2 Pd2+ + 4 e- yields 2 Pd

Answer 1

In general oxidation is defined as gain of oxygen or loss of electron or hydrogen by an atom. Reduction is defined as gain of electron or hydrogen or loss of oxygen by an atom.

In a balanced redox reaction we have two half reactions

a) reduction half reaction : the oxidation number of element decreases

b) oxidation half reaction : the oxidation number of element increases

`Pb(s) + Pd(NO_(3) )_(2)(aq)---> Pb(NO_(3) )_(2)(aq)+ Pd(s)`

The element undergoing reduction is Pd.

the oxidation number of Pd decreases from +2 to 0

Thus the reduction half reaction will be

`Pd^(+2) + 2e- --->Pd(s)`

The Pd (II) ion will take two electrons and will give Pd (0)

Answer is
`Pd^(+2) + 2e- --->Pd(s)`