Answered

Given the balanced ionic equation:

3Pb2+ + 2Cr ==> 3Pb + 2Cr3+

What is the number of moles of electrons gained by 3.0 moles of lead ions?

(1) 5.0 mol (3)3.0 mol

(2) 2.0 mol (4) 6.0mol

Verified Answer :

pyromorphite

answer:  6......................

Answer : The correct option is, (4) 6.0 mol

Explanation :

The given balanced ionic equation is,

\(3Pb^{2+}+2Cr\rightarrow 3Pb+2Cr^{3+}\)

In this reaction, lead undergoes reduction and chromium undergoes oxidation.

  • Oxidation reaction : It is the reaction in which a substance looses its electrons. In this oxidation state increases.
  • Reduction reaction : It is the reaction in which a substance gains electrons. In this oxidation state decreases.

Half reactions of oxidation and reduction are :

Oxidation : \(2Cr\rightarrow 2Cr^{3+}+6e^-\)

Reduction : \(3Pb^{2+}+6e^-\rightarrow 3Pb\)

From the reduction reaction, we conclude that 6 moles of electrons gained by the 3 moles of lead ions.

Hence, the correct option is, (4) 6.0 mole

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