1

IIT-JEE 1994

Subjective

+4

-0

The Edison storage cells is represented as

Fe(s) | FeO(s) | KOH (aq) | Ni

The half-cell reactions are:

Ni

FeO(s) + H

(i) What is the cell reaction?

(ii) What is the cell e.m.f? How does it depend on the concentration of KOH?

(iii) What is the maximum amount of electrical energy that can be obtained from one mole of Ni

Fe(s) | FeO(s) | KOH (aq) | Ni

_{2}O_{3}(s) | Ni(s)The half-cell reactions are:

Ni

_{2}O_{3}+ H_{2}O (l) + 2e^{-}$$\leftrightharpoons$$ 2NiO(s) + 2OH^{-}; E^{o}= +0.40VFeO(s) + H

_{2}O(l) + 2e^{-}$$\leftrightharpoons$$ Fe(s) + 2OH^{-}; E^{o}= -0.87V(i) What is the cell reaction?

(ii) What is the cell e.m.f? How does it depend on the concentration of KOH?

(iii) What is the maximum amount of electrical energy that can be obtained from one mole of Ni

_{2}O_{3}?2

IIT-JEE 1993

Subjective

+2

-0

The standard reduction potential for the half-cell

$$NO_3^-$$ + 2H

(i) Calculate the reduction potential in 8 M H

(ii) What will be the reduction potential of the half-cell in a neutral solution? Assume all the other species to be at unit concentration.

$$NO_3^-$$ + 2H

^{+}(aq) + e $$\to$$ NO_{2}(g) + H_{2}O is 0.78 V(i) Calculate the reduction potential in 8 M H

^{+}(ii) What will be the reduction potential of the half-cell in a neutral solution? Assume all the other species to be at unit concentration.

3

IIT-JEE 1993

Subjective

+2

-0

Chromium metal can be plated out from an acidic solution containing CrO

CrO

Calculate (i) how many grams of chromium will be plated out by 24,000 coulombs and (ii) how long will it take to plate out 1.5 g of chromium by using 12.5 amp current.

_{3}according to the following equationCrO

_{3}(aq) + 6H^{+}(aq) + 6e^{-}$$\to$$ Cr(s) + 3H_{2}OCalculate (i) how many grams of chromium will be plated out by 24,000 coulombs and (ii) how long will it take to plate out 1.5 g of chromium by using 12.5 amp current.

4

IIT-JEE 1992

Subjective

+4

-0

For the galvanic cell

Ag | AgCl(s), KCl (0.2M) || KBr (0.001M), AgBr(s) | Ag

Calculate the EMF generated and assign correct polarity to each electrode for a spontaneous process after taking into account the cell reaction at 25

[K

Ag | AgCl(s), KCl (0.2M) || KBr (0.001M), AgBr(s) | Ag

Calculate the EMF generated and assign correct polarity to each electrode for a spontaneous process after taking into account the cell reaction at 25

^{o}C.[K

_{sp}(AgCl) = 2.8 $$times$$ 10^{-10}; K_{sp}(AgBr) = 3.3 $$times$$ 10^{-13}]Questions Asked from Electrochemistry (Subjective)

Number in Brackets after Paper Indicates No. of Questions

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