For $I_{2} + 2 e^{-} \to 2 I^{-}, standard reduction potential = + 0.54 Volt .$
For $2 B r^{-} \to B r_{2} + 2 e^{-}, standard oxidation potential = - 1.09 Volt .$
For $F e \to F e^{2 +} + 2 e^{-}, standard oxidation potential = + 0.44 Volt .$
Out of the below given reactions, how many reactions are spontaneous in nature (predict from the above data) ?
$B r_{2} + 2 I^{-} \to 2 B r^{-} + I_{2}$
$F e + B r_{2} \to F e^{2 +} + 2 B r^{-}$
$F e + I_{2} \to F e^{2 +} + 2 I^{-}$
$I_{2} + 2 B r^{-} \to 2 I^{-} + B r_{2}$

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Solution

We know that,
$Δ G^{o} = - n F E_{c e l l}^{o}$
For a spontanesous reaction, $Δ G < 0$ which is when $E_{c e l l}^{o} > 0$

(a) $B r_{2} + 2 e^{-} \to 2 B r^{-} E_{B r_{2} / B r^{-}}^{o} = 1.09 V$
$2 I^{-} \to I_{2} + 2 e^{-} E_{I^{-} / I_{2}}^{o} = - 0.54 V$
$∴ for B r_{2} + 2 I^{-} \to I_{2} + 2 B r^{-} E^{o} = (1.09 - 0.54) V = 0.55 V$
Hence, this is a spontaneous reaction.

(b)
$F e \to F e^{2 +} + 2 e^{-} E_{F e / F e^{2 +}}^{o} = 0.44 V$
$B r_{2} + 2 e^{-} \to 2 B r^{-} E_{B r_{2} / B r^{-}}^{o} = 1.09 V$
$∴ B r_{2} + F e \to F e^{2 +} + 2 B r^{-} E^{o} = (0.44 + 1.09) V = 1.53 V$
So, this reaction is also spontaneous.

(c)
$F e \to F e^{2 +} + 2 e^{-} E_{F e / F e^{2 +}}^{o} = 0.44 V$
$I_{2} + 2 e^{-} \to 2 I^{-} E_{I_{2} / I^{-}}^{o} = 0.54 V$
$∴ I_{2} + F e \to F e^{2 +} + 2 I^{-} E^{o} = (0.44 + 0.54) V = 0.98 V$
Hence, this is also a spontaneous reaction.

(d)
$I_{2} + 2 e^{-} \to 2 I^{-} E_{I_{2} / I^{-}}^{o} = 0.54 V$
$2 B r^{-} \to B r_{2} + 2 e^{-} E_{B r^{-} / B r_{2}}^{o} = - 1.09 V$
$∴ I_{2} + 2 B r^{-} \to B r_{2} + 2 I^{-} E^{o} = (0.54 - 1.09) V = - 0.55 V$
This reaction is non-spontaneous.

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Similar questions

Q. For

I_{2} + 2 e^{-} \to 2 I^{-} standard reduction potential = + 0.54 Volt .

For

2 B r^{-} \to B r_{2} + 2 e^{-} standard oxidation potential = - 1.09 Volt .

For

F e \to F e^{2 +} + 2 e^{-}, standard oxidation potential = + 0.44 Volt .

Which of the following reaction(s) is/are spontaneous:

Q. For

I_{2} + 2 e^{-} \to 2 I^{-}, standard reduction potential = + 0.54 Volt .

For

2 B r^{-} \to B r_{2} + 2 e^{-}, standard oxidation potential = - 1.09 Volt .

For

F e \to F e^{2 +} + 2 e^{-}, standard oxidation potential = + 0.44 Volt .

Out of the below given reactions, how many reactions are spontaneous in nature (predict from the above data) ?

B r_{2} + 2 I^{-} \to 2 B r^{-} + I_{2}

F e + B r_{2} \to F e^{2 +} + 2 B r^{-}

F e + I_{2} \to F e^{2 +} + 2 I^{-}

I_{2} + 2 B r^{-} \to 2 I^{-} + B r_{2}

Given that : $I_{2} + 2 e^{-} \to 2 I^{-}; E_{I_{2} / I^{-}}^{o}$ = 0.54V; $B r_{2} + 2 e^{-} \to 2 B r^{-}; E_{B r_{2} / B r^{-}}^{o}$ = 1.69V. Predict which of the following is true:

Q. Which of the following is the cell reaction that occurs when the following half-cells are combined?

I_{2} + 2 e^{-} \to 2 I^{-} (1 M)

;

E^{o} = + 0.54

B r_{2} + 2 e^{-} \to 2 B r^{-} (1 M); E^{o} = + 1.09

Q. Iodine

(I_{2})

and bromine

(B r_{2})

are added to a solution containing iodide

(I^{-})

and bromide

(B r^{-})

ions. What reaction would occur if the concentration of each species is 1M? The electrode potentials for the reactions are:
(i)

I_{2} + 2 e^{-} \to 2 I^{-}, E^{\circ} = + 0.54 V

(ii)

B r_{2} + 2 e^{-} \to 2 B r^{-}, E^{\circ} = + 1.08 V

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