Start Learning Free

Before You Begin

Question #44314

Difficulty: 8/10 | 🟢 Free

The Question

Consider the standard reduction potentials at 298 K298\text{ K} for Group 14 elements \ce{Sn} and \ce{Pb}: E∘(\ceSn4+/\ceSn2+)=+0.15 VE^\circ(\ce{Sn^{4+}}/\ce{Sn^{2+}}) = +0.15\text{ V} E∘(\cePb4+/\cePb2+)=+1.69 VE^\circ(\ce{Pb^{4+}}/\ce{Pb^{2+}}) = +1.69\text{ V} E∘(\ceSn2+/\ceSn)=−0.14 VE^\circ(\ce{Sn^{2+}}/\ce{Sn}) = -0.14\text{ V} E∘(\cePb2+/\cePb)=−0.13 VE^\circ(\ce{Pb^{2+}}/\ce{Pb}) = -0.13\text{ V}

Two thermodynamic equilibrium constants are defined as follows: K1K_1: Equilibrium constant for the oxidation of \ce{Sn^{2+}(aq)} by \ce{Pb^{4+}(aq)}.. K_2:Theequilibriumconcentrationratio: The equilibrium concentration ratio \frac{[\ce{Sn^{2+}}]}{[\ce{Pb^{2+}}]}$ established when excess finely divided \ce{Sn(s)} and \ce{Pb(s)} metals are added to an aqueous solution containing \ce{Pb^{2+}(aq)} and \ce{Sn^{2+}(aq)} ions.

Assuming 2.303RTF=0.06 V\frac{2.303 RT}{F} = 0.06\text{ V}, calculate the values of K1K_1 and K2K_2 respectively.

Options

  • A.

    10154/310^{154/3} and 101/310^{1/3}

  • B.

    1077/310^{77/3} and 10−1/310^{-1/3}

  • C.

    10154/310^{154/3} and 10−1/310^{-1/3}

  • D.

    1077/310^{77/3} and 101/610^{1/6}

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Exception_Exposure

Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.

Concepts Behind This Question

Inert Pair Effect|Metal Activity Series Logic|E° (M²⁺/M) Anomalies

Why This Question Is Tricky

Common Mistakes

This problem tests the 'Metal Activity Series Logic' trap combined with the 'Inert Pair Effect'.

Students typically assume that metallic character and reactivity increase monotonically down a group, which would imply Pb displaces Sn (leading to a negative E° and K_2 = 10^{-1/3}).

However, the relativistic contraction of the 6s orbital in Pb significantly increases its ionization enthalpy (IE_1 + IE_2) compared to Sn.

This hidden variable makes Pb less reactive than Sn, resulting in a less negative reduction potential for Pb2+/Pb.

The problem forces students to trust the thermodynamic data over naive periodic trends and correctly apply the Nernst equation with n=2 for both the +4/+2 and +2/0 couples.

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterClassification of Elements and Periodicity in Properties - Class 11 Part 1
ConceptInert Pair Effect
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree