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Redox Reactions and Couple

The values of...

Question

The values of $E^{\circ}$ of some of the reactions are given below:
$I_{2} + 2 e^{-} \to 2 I^{-}; E^{\circ} = + 0.54 v o l t$
$C l_{2} + 2 e^{-} \to 2 C l^{-}; E^{\circ} = + 1.36 v o l t$
$F e^{2 +} + e^{-} \to F e^{2 +}; E^{\circ} = + 0.76 v o l t$
$C e^{4 +} + e^{-} \to C e^{3 +}; E^{\circ} = + 1.60 v o l t$
$S n^{4 +} + 2 e^{-} \to S n^{2 +}; E^{\circ} = + 0.15 v o l t$
On the basis of the above data, answer the following questions:
(a) Whether $F e^{3 +}$ oxidises $C e^{3 +}$ or not?
(b) Whether $I_{2}$ displaces chlorine from $K C l$ ?
(c) Whether the reaction between $F e C l_{3}$ and $S n C l_{2}$ occurs or not?

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Solution

(a) Chemical reaction,
$F e^{3 +} + C e^{3 +} \to C e^{4 +} + F e^{2 +}$
Two half reactions,
$F e^{3 +} + e \to F e^{2 +}; R e d u c t i o n; E^{\circ} = 0.76 v o l t$
$C e^{3 +} \to C e^{4 +} + e^{-}; O x i d a t i o n; E_{O X}^{\circ} = - 1.60 v o l t - ------------------------------ -$
$A d d i n g; e m f = - 0.84 v o l t$
Since, emf is negative, the reaction does not occur, i.e., $F e^{3 +}$ does not oxidise $C e^{3 +}$ .
(b) Chemical reaction,
$I_{2} + 2 K C l = 2 K I = C l_{2}$
Half reactions,
$I_{2} + 2 e^{-} \to 2 I^{-}; R e d u c t i o n; E^{\circ} = 0.53 v o l t$
$2 C l^{-} \to C l_{2} + 2 e^{-}; u n d e r l i n e O x i d a t i o n; E_{O X}^{\circ} = - 1.36 v o l t$
$A d d i n g; e m f = - 0.82 v o l t$
Since, emf is negative, the reaction does not occur, i.e., $I_{2}$ does not displace $C l_{2}$ from $K C l$ .
(c) Chemical reaction,
$S n C l_{2} + 2 F e C l_{3} \to S n C l_{4} + 2 F e C l_{2}$
Half reactions,
$F e^{3 +} + e^{-} \to F e^{2 +}; R e d u c t i o n; E^{\circ} = 0.76 v o l t$
$S n^{2 +} \to S n^{4 +} + 2 e^{-}; O x i d a t i o n; E^{\circ} = - 0.15 v o l t - ---------------------------- -$
$A d d i n g; e m f = + 0.61 v o l t$
Since, emf is positive, the reaction will occur.

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Similar questions

H g_{2} C l_{2} + C l_{2} \to 2 H g^{+} + 4 C l^{-}

H g_{2} C l_{2} + 2 e^{-} \to 2 H g + 2 C l^{-}; E^{\circ} = 0.270 v o l t

H g_{2}^{2 +} \to 2 H g^{2 +} + 2 e^{-}; E^{\circ} = - 0.92 v o l t

2 H g \to H g_{2}^{2 +} + 2 e^{-}; E^{\circ} = - 0.79 v o l t

C l_{2} + 2 e^{-} \to 2 C l^{-}; E^{\circ} = 1.36 v o l t

E^{0}

I_{2} (g) + 2 e^{-} \to 2 I^{-} (a q); E^{0} = + 0.54 V

C l_{2} (g) + 2 e^{-} \to 2 C l^{-} (a q); E^{0} = + 1.36 V

F e^{3 +} (a q) + e^{-} \to F e^{2 +} (a q); E^{0} = + 0.76 V

C e^{4 +} (a q) + e^{-} \to C e^{3 +} (a q); E^{0} = + 1.60 V

S n^{4 +} (a q) + 2 e^{-} \to S n^{2 +} (a q); E^{0} = + 0.15 V

E

E^{\circ}

N i | N i^{2 +} | | C u^{2 +} | C u

N i^{2 +} + 2 e^{-} \to N i; E^{\circ} = - 0.25 v o l t

C u^{2 +} + 2 e^{-} \to C u; E^{\circ} = + 0.34 v o l t

[N i^{2 +}] = 1 M

[C u^{2 +}] = 10^{- 3} M)

E^{\circ}

Z n \to Z n^{2 +} + 2 e^{-}; E^{\circ} = + 0.76 v o l t

F e \to F e^{2 +} + 2 e^{-}; E^{\circ} = + 0.41 v o l t

F e^{2 +} + Z n \to Z n^{2 +} + F e

C u^{\oplus} + e^{-} \to C u, E^{⊖} = x_{1}

C u^{2 +} + 2 e^{-} \to C u, E^{⊖} = x_{2}

C u^{2 +} + e^{-} \to C u, E^{⊖}

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