The EMF of the standard weston cadmium cell Cd ( 12 . 5 % ) in Hg 3 CdSO 4 , 8 H 2 O (solid) ∣ saturated solution of CdSO 4 ‖ Hg 2 SO 4 ( s ) ∣ Hg is 1 . 0180 volts at 25 ° C and the temperature coefficient of the cell, ∂ E ∂ T P = - 4 . 0 × 10 - 5 V / degree . Calculate ΔG , ΔH and ∆ S for the reaction in the cell when n = 2 .

Cd 12 . 5 % in Hg | 3 CdSO 4 , 8 H 2 O | saturated sol n of CdSO 4 | H 2 SO 4 | Hg is E = 1 . 018 V δE δT P = - nET = - 21 . 018 × 96500 = - 196 . 474 KJ ∆ S = nf · δE δT = 2 × 96500 × - 4 × 10 - 5 = 7 . 725 K - 1 ∆ G = ∆ H - T ∆ S ∆ H = - 196 . 474 + 298 × - 7 . 72 1000 = - 196 . 474 - 2 . 3 = 198 . 774 KJ

The standard electromotive force of the cell : Fe Fe 2 + ( aq ) Cd 2 + Cd is 0 . 0372 V . The temperature coefficient of e.m.f. is - 0 . 125 VK - 1 . Calculate the quantities ΔG ° , ΔH ° ΔS ° and at 25 ° C .

The emf of cell Fe Fe 2 + ( aq ) Cd 2 + Cd , E 0 = 0 . 0372 ∴ ∆ G 0 = - nfE 0 = - 2 × 96500 × 0 . 0372 ∆ G 0 = - 7179 . 6 J = - 7 . 18 KJ ∆ S = nf δE cell δT P ∴ ∆ S 0 = 2 × f × - 0 . 125 - 7180 = ∆ H 0 + 298 2 × 96500 × 0 . 125 ∴ ∆ H 0 = - 7196 . 43 KJ .

HARD

JEE Main/Advance

IMPORTANT

Earn 100

In two vessels each containing $500 ml$ water, $0.5 m$ mol of aniline $(K_{b} = 10^{- 9})$ and $25 m$ mol of $HCl$ are added separately. Two hydrogen electrodes are constructed using these solutions. Calculate the emf of cell made by connecting them appropriately.

Important Questions on Electrochemistry

MEDIUM

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 10

Given,

E ° = - 0.27 V

for the

{Cl}^{-} |{PbCl}_{2}| Pb

couple and

- 0.12 V

for the

{Pb}^{2 +} ∣ Pb

couple, determine

K_{sp}

for

{PbCl}_{2}

25 ° C

at ? (Take

\frac{2.303 RT}{F} = 0.06)

MEDIUM

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 12

The

EMF

of the standard weston cadmium cell

Cd

(12.5 %)

Hg

3 {CdSO}_{4}, 8 H_{2} O

(solid)

∣

saturated solution of

{CdSO}_{4} ‖ {Hg}_{2} {SO}_{4} (s) ∣ Hg

1.0180

volts at

25 ° C

and the temperature coefficient of the cell,

{(\frac{\partial E}{\partial T})}_{P} = - 4.0 \times 10^{- 5} V / degree

. Calculate

ΔG, ΔH

and

∆ S

for the reaction in the cell when

n = 2

MEDIUM

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IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 13

ΔH

for the reaction

Ag (s) + \frac{1}{2} {Hg}_{2} {Cl}_{2} (s) \to AgCl (s) + Hg (ℓ)

+ 1280 cal

is at

25 ° C .

This reaction can be conducted in a cell for which the emf

= 0.0455

volt at this temperature. Calculate the temperature coefficient of the emf.

MEDIUM

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 14

The standard electromotive force of the cell :

Fe |{Fe}^{2 +} (aq)| |{Cd}^{2 +}| Cd

0.0372 V

. The temperature coefficient of e.m.f. is

- 0.125 {VK}^{- 1}

. Calculate the quantities

ΔG °, ΔH °

{ΔS}^{°}

and at

25 ° C

EASY

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 15

The voltage of a certain cell has

25 ° C

and

20 ° C

, and their standard potential

0.3525 V

and

0.3533 V

respectively. If the number of electrons involved in the overall reactions are two, calculate

ΔG °, ΔS °

and

ΔH ° at 25 ° C

MEDIUM

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 16

A metal is known to form fluoride

{MF}_{2}

. When

10 A

of electricity is passed through a molten salt for

330 \sec

1.95 g

of metal is deposited. Find the atomic weight of

M

. What will be the quantity of electricity required to deposit the same mass of

Cu

from

{CuSO}_{4} ?

HARD

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 17

Find out the volume of gases evolved by passing

0.965 A

current for

1 hr

through an aqueous solution of

{CH}_{3} COONa

25 ° C

and

1 atm

HARD

JEE Main/Advance

IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 9 - Electrochemistry>Exercise-5>Q 18

One of the methods of preparation of per disulphuric acid,

H_{2} S_{2} O_{8},

involve electrolytic oxidation of

H_{2} {SO}_{4}

at anode

(2 H_{2} {SO}_{4} ⟶ H_{2} S_{2} O_{8} + 2 H^{+} + 2 e^{-})

with oxygen and hydrogen as by-products. In such an electrolysis,

9.722 L

H_{2}

of and

2.35 L

O_{2}

were generated at

STP

. What is the weight of

H_{2} S_{2} O_{8}

formed'?

In two vessels each containing 500 ml water, 0.5 m mol of aniline Kb=10-9 and 25 m mol of HCl are added separately. Two hydrogen electrodes are constructed using these solutions. Calculate the emf of cell made by connecting them appropriately.

Important Questions on Electrochemistry

Learn and Prepare for any exam you want !

In two vessels each containing $500 ml$ water, $0.5 m$ mol of aniline $(K_{b} = 10^{- 9})$ and $25 m$ mol of $HCl$ are added separately. Two hydrogen electrodes are constructed using these solutions. Calculate the emf of cell made by connecting them appropriately.