The standard reduction potential data at 25- C is given below-E- Fe3-Fe2- 0-77 V- E- Fe2-Fe - - 0-44 V-E- Cu2-Cu- 0-34 V- E-Cu-Cu - - 0-52 V-E- O2 g- 4H- - 4e- - 2H2 O - - 1-23 V-E- O2 g- 2H2 O - 4e- - 4OH- - - 0-40 VE- Cr3-Cr- - 0-74 V- E- Cr2-Cr - - 0-91 VMatch E- of the rebox pair in Column I with the values given in Column II and select the correct answer using the code given below the lists- Column I Column II- P- E- Fe3-Fe 1- -0-18 V- Q-E- 4H2 O - 4H- - 4OH- 2- -0-4 V- R- E- Cu2- - Cu - 2 Cu- 3- -0-04 V- S- E- Cr3-Cr2- 4- -0-83 V- -

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Byju's Answer

Standard XII

Chemistry

Electrochemical Series

The standard ...

Question

The standard reduction potential data at $25^{\circ} C$ is given below.

$E^{\circ} (F e^{3 +} / F e^{2 +}) = 0.77 V; E^{\circ} (F e^{2 +} / F e) = - 0.44 V; E^{\circ} (C u^{2 +} / C u) = 0.34 V; E^{\circ} (C u^{+} / C u) = + 0.52 V; E^{\circ} (O_{2} (g) + 4 H^{+} + 4 e^{-}) \to 2 H_{2} O = + 1.23 V; E^{\circ} (O_{2} (g) + 2 H_{2} O + 4 e^{-}) \to 4 O H^{-} = + 0.40 V E^{\circ} (C r^{3 +} / C r) = - 0.74 V; E^{\circ} (C r^{2 +} / C r) = + 0.91 V$

Match $E^{\circ}$ of the rebox pair in Column I with the values given in Column II and select the correct answer using the code given below the lists.

$\begin{matrix} C o l u m n I & C o l u m n I I P . E^{\circ} (F e^{3 +} / F e) & 1. - 0.18 V Q . E^{\circ} (4 H_{2} O ⇌ 4 H^{+} + 4 O H^{-}) & 2. - 0.4 V R . E^{\circ} (C u^{2 +} + C u \to 2 C u^{+}) & 3. - 0.04 V S . E^{\circ} (C r^{3 +} / C r^{2 +}) & 4. - 0.83 V \end{matrix}$

P - (4) Q - (1) R - (2) S - (3)

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P - (2) Q - (3) R - (4) S - (1)

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P - (1) Q - (2) R - (3) S - (4)

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P - (3) Q - (4) R - (1) S - (2)

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Solution

The correct option is D
P - (3) Q - (4) R - (1) S - (2)

PLAN When different number of electrons are involved in a redox reaction.
$Δ G_{n e t}^{\circ} = Δ G_{1}^{\circ} + Δ G_{2}^{\circ} - n_{3} F E_{3}^{\circ} = - n_{1} F E_{1}^{\circ} - n_{2} F E_{2}^{\circ} ∴ E_{3}^{\circ} = \frac{n_{1} E^{\circ} + n_{2} E_{2}^{\circ}}{n_{3}}$
$(P) E_{3}^{\circ} (F e^{3 +} / F e)$
Net reaction $F e^{3 +} \to F e$
is obtained from
$F e^{3 +} + e^{-} \to F e^{2 +} F e^{2 +} + 2 e^{-} \to F e - ------------------ - ∵ F e^{3 +} + 3 e^{-} \to F e - ------------------ - n E^{\circ} - ----------------- - n_{1} = 1 E_{1}^{o} = 0.77 V n_{2} = 2 E_{2}^{o} = 0.44 V n_{3} = 3 E_{3}^{o} ?$
$E_{3}^{\circ} = \frac{n_{1} E_{1}^{\circ} + n_{2} E_{2}^{\circ}}{n_{3}} = \frac{0.77 + 2 (- 0.44)}{3} = \frac{- 0.11}{3} = - 0.04 V$
Thus, P - (3)
Net reaction
$4 H_{2} O ⇌ 4 H^{+} + 4 H^{+} + 4 O H^{-}$
is obtained from
$2 H_{2} O \to O_{2} + 4 H^{+} + 4 e^{-} 2 H_{2} O + O_{2} + 4 e^{-} \to O H^{-} - --------------------------- - 4 H_{2} O \to 4 H^{+} + 4 e^{-} - -------------------- -$
$n E^{\circ} - --------------- - n_{1} = 4 - 1.23 V n_{2} = 4 + 0.40 V n_{3} = 4 ? E_{3}^{\circ} = \frac{n_{1} E^{\circ} + n_{2} E_{2}^{\circ}}{n_{3}} = E_{1}^{\circ} + E_{2}^{\circ} = - 1.23 + 0.40 = - 0.83 V$
Thus, Q - (4)
$(R) C u^{2 +} + C u \to 2 C u^{+} O x i d a t i o n R e d u c t i o n$
$E^{\circ} o f C u^{2 +} \to C u^{+}$ is also required
$C u^{2 +} + 2 e^{-} \to C u C u \to C u^{+} + e^{-} - ----------------------- - C u^{2 +} + e^{-} \to C u^{+} - ------------------ -$
$n E^{\circ} - ------------------ - 2 0.34 V 1 - 0.52 V E_{3}^{\circ} ? E_{3}^{\circ} = \frac{n_{1} E_{1}^{\circ} + n_{2} E_{2}^{\circ}}{n_{3}} = \frac{2 \times 0.34 + 1 \times (- 0.52)}{1} = 0.16 V$
Also,
$C u \to C u^{+} + e^{-} C u^{2 +} + e^{-} \to C u^{+} - ------------------ - n E^{\circ} - ------------------ - n = 1, 0.52 V n_{2} = 1 - 0.10 V C u^{2 +} + C u \to 2 C u^{+} E^{\circ} = - 0.52 + 0.16 = - 0.36 V$
Thus, (R) - (1)
$(S) C r^{3 +} \to C r^{2 +}$ is obtained from
$C r^{(} 3 +) + 3 e^{-} \to C r C r \to C r^{(} 2 +) + 2 e^{-} - -------------------- - C r^{3 +} + e^{-} \to C r^{2 +} - ------------------- - n E^{\circ} 3 - 0.74 V 2 + 0.91 V 1 ? E_{3}^{\circ} = \frac{- 0.74 \times 3 + 2 \times 0.91}{1} = - 0.4 V$
Thus, S = (2)
P - (3), (Q) - (4), R - (1), S - (2)

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Similar questions

The standard reduction potential data at $25^{\circ} C$ is given below.

$E^{\circ} (F e^{3 +} / F e^{2 +}) = 0.77 V; E^{\circ} (F e^{2 +} / F e) = - 0.44 V; E^{\circ} (C u^{2 +} / C u) = 0.34 V; E^{\circ} (C u^{+} / C u) = + 0.52 V; E^{\circ} (O_{2} (g) + 4 H^{+} + 4 e^{-}) \to 2 H_{2} O = + 1.23 V; E^{\circ} (O_{2} (g) + 2 H_{2} O + 4 e^{-}) \to 4 O H^{-} = + 0.40 V E^{\circ} (C r^{3 +} / C r) = - 0.74 V; E^{\circ} (C r^{2 +} / C r) = + 0.91 V$

Match $E^{\circ}$ of the rebox pair in Column I with the values given in Column II and select the correct answer using the code given below the lists.

$\begin{matrix} C o l u m n I & C o l u m n I I P . E^{\circ} (F e^{3 +} / F e) & 1. - 0.18 V Q . E^{\circ} (4 H_{2} O ⇌ 4 H^{+} + 4 O H^{-}) & 2. - 0.4 V R . E^{\circ} (C u^{2 +} + C u \to 2 C u^{+}) & 3. - 0.04 V S . E^{\circ} (C r^{3 +} / C r^{2 +}) & 4. - 0.83 V \end{matrix}$

Q. The standard reduction potential data at

25^{o} C

is given below:

E^{o} (F e^{3 +}, F e^{2 +}) = + 0.77 V

;

E^{o} (F e^{2 +}, F e) = - 0.44 V

;

E^{o} (C u^{2 +}, C u) = + 0.34 V

;

E^{o} (C u^{+}, C u) = + 0.52 V

;

E^{o} (O_{2} (g) + 4 H^{+} + 4 e^{-} \to 2 H_{2} O) = + 1.23 V

;

E^{o} (O_{2} (g) + 2 H_{2} O + 4 e^{-} \to 4 O H^{-}) = + 0.4 V

;

E^{o} (C r^{3 +}, C r) = - 0.74 V

;

E^{o} (C r^{2 +}, C r) = - 0.91 V

;
Which of the following statements is/are correct on the basis of above data:

Q. Which of the following transformations can be carried out by using HI as a reducing agent, under acidic conditions?[Given:

I_{2} (s) \to 2 I^{-}

;

E^{⊖} = 0.54 V]

(i)

C u^{+} \to C u (s); E^{⊖} = 0.52 V

(ii)

C r^{3 +} \to C r^{2 +}; E^{⊖} = - 0.41 V

(iii)

F e^{3 +} \to F e^{2 +}; E^{⊖} = 0.77 V

(iv)

F e^{2 +} \to F e (s); E^{⊖} = - 0.44 V

Q. Rank the following elements by increasing ease of oxidation with most easily oxidized LAST:

C d, C u, N i, F e

Standard Reduction Potentials at

25^{\circ} C

Half-Reaction	$E^{\circ} (V)$
$F_{2} + 2 e^{-} \to 2 F^{-}$	$2.87$
$A g^{2} + e^{-} \to A g^{+}$	$1.99$
$C o^{3 +} + e^{-} \to C o^{2 +}$	$1.82$
$H_{2} O_{2} + 2 H^{+} + 2 e^{-} \to 2 H_{2} O$	$1.78$
$M n O_{4}^{-} + 4 H^{+} + 3 e^{-} \to M n O_{2} + 2 H_{2} O$	$1.68$
$2 e^{-} + 2 H^{+} + I O_{4}^{-} \to I O_{3}^{-} + H_{2} O$	$1.60$
$M n O_{4}^{-} + 8 H^{+} + 5 e^{-} \to M n^{2 +} + 4 H_{2} O$	$1.51$
$A u^{3 +} + 3 e^{-} \to A u$	$1.50$
$C l_{2} + 2 e^{-} \to 2 C l^{-}$	$1.36$
$O_{2} + 4 H^{+} + 4 e^{-} \to 2 H_{2} O$	$1.23$
$M n O_{2} + 4 H^{+} + 2 e^{-} \to M n^{2 +} + 2 H_{2} O$	$1.21$
$B r_{2} + 2 e^{-} \to 2 B r^{-}$	$1.09$
$N O_{3}^{-} + 4 H^{+} + 3 e^{-} \to N O + 2 H_{2} O$	$0.96$
$C l O_{2} + e^{-} \to C l O_{2}$	$0.954$
$2 H g^{2 +} + 2 e^{-} \to H g_{2}^{2 +}$	$0.91$
$A g^{+} + e^{-} \to A g$	$0.80$
$H g_{2}^{2 +} + 2 e^{-} \to 2 H g$	$0.80$
$F e^{3 +} + e^{-} \to F e^{2 +}$	$0.77$
$O_{2} + 2 H^{+} + 2 e^{-} \to H_{2} O_{2}$	$0.68$
$M n O_{4}^{-} + e^{-} \to M n O_{4}^{2 -}$	$0.56$
$I_{2} + 2 e^{-} \to 2 I^{-}$	$0.54$
$C u^{+} + e^{-} \to C u$	$0.52$
$O_{2} + 2 H_{2} O + 4 e^{-} \to 4 O H^{-}$	$0.40$
$C u^{2 +} + 2 e^{-} \to C u$	$0.34$
$A g C l + e^{-} \to A g + C l^{-}$	$0.22$
$C u^{2 +} + e^{-} \to C u^{+}$	$0.16$
$2 H^{+} + 2 e^{-} \to H_{2}$	$0.00$
$F e^{3 +} + 3 e^{-} \to F e$	$- 0.036$
$P b^{2 +} + 2 e^{-} \to P b$	$- 0.13$
$N i^{2 +} + 2 e^{-} \to N i$	$- 0.23$
$C d^{2 +} + 2 e^{-} \to C d$	$- 0.40$
$F e^{2 +} + 2 e^{-} \to F e$	$- 0.44$
$C r^{3 +} + e^{-} \to C r^{2 +}$	$- 0.50$
$C r^{3 +} + 3 e^{-} \to C r$	$- 0.73$
$Z n^{2 +} + 2 e^{-} \to Z n$	$- 0.76$
$2 H_{2} O + 2 e^{-} \to H_{2} + 2 O H^{-}$	$- 0.83$
$M n^{2 +} + 2 e^{-} \to M n$	$- 1.18$
$A l^{3 +} + 3 e^{-} \to A l$	$- 1.66$
$H_{2} + 2 e^{-} \to 2 H^{-}$	$- 2.23$
$M g^{2 +} + 2 e^{-} \to M g$	$- 2.37$
$N a^{+} + e^{-} \to N a$	$- 2.71$
$C a^{2 +} + 2 e^{-} \to C a$	$- 2.76$
$B a^{2 +} + 2 e^{-} \to B a$	$- 2.90$
$K^{+} + e^{-} \to K$	$- 2.92$
$L i^{+} + e^{-} \to L i$	$- 3.05$