Nernst Equation and its Applications

IMPORTANT

Nernst Equation and its Applications: Overview

This topic covers concepts, such as, Nernst's Equation etc.

Important Questions on Nernst Equation and its Applications

HARD
IMPORTANT

Calculate the standard electrode potential of Ni2+/Ni electrode, if emf of the cell Ni (s)|Ni2+(0.01M)||Cu2+(0.1M)|Cu(s) is 0.059 V.

 [Given: ECu2+/Cuo=+0.34V]

HARD
IMPORTANT

The cell emf and ΔrG° for a cell reaction at 25°C are,

 Zn(s)|Zn2+(0.1M)||Cd2+(0.01M)|Cd ​(s)

 [Given,EZn2+/Zno=0.763V,ECd2+/Cdo=0.403V]

 1​ F=96,500Cmol1,R=8.314JK1mol1.

MEDIUM
IMPORTANT

i The  Ecell° of the electrochemical cell representing the reaction is

2Crs+3Fe2+aq2Cr3+aq+3Fes

ii The Ecell at  25°C when Cr+3=0.1 M and Fe2+=0.01 M will be?

ECr+3Cr°=0.74VEFe+2Fe°=0.44V

HARD
IMPORTANT

The standard reduction potential of   C u 2+ /CuandA g + /Ag  electrodes is 0.337 and 0.799 volt respectively. Construct a galvanic cell using these electrodes so that its standard e.m.f. is positive. For what concentration of   A g + will the e.m.f. of the cell at   25°C be zero if the concentration of   C u 2+  is 0.01 M?

HARD
IMPORTANT

The standard reduction potential for Cu2+/Cu is +0.34V.  Calculate the reduction potential at  pH=14 for the above couple.  Ksp  of  Cu(OH)2  is  1.0×1019.

MEDIUM
IMPORTANT

Two student use same stock solution of ZnSO4 and a solution of CuSO4. The EMF of one cell is 0.03 V higher than the other. The concentration of  CuSO4 in the cell with higher EMF value is 0.5 M. Find out the concentration of CuSO4 in the other cell  2.303RTF=0.06:

HARD
IMPORTANT

Find the equilibrium constant for the reaction,  2Feaq3++3Iaq-2Feaq2++I3(aq)- .  For   Fe 3 + / Fe 2 + and I 3 - 1 / I - 1 , the standard reduction potentials in acidic conditions are 0.77V and 0.54V respectively.

HARD
IMPORTANT

The EMF of a cell corresponding to the reaction:

Zn(s)+2H+(aq)Zn2+aq(0.1  M)+H2(g)  (1  atm.)  is  0.28  volt  at  25°C.

The pH of the solution at the hydrogen electrode?
E Z n 2+ /Zn o =0.76volt; E H + / H 2 o =0

MEDIUM
IMPORTANT

If 6.539×102 g of metallic zinc is added to 100 mL saturated solution of AgCl, then Ag s precipitates in the above reaction.

Ksp AgCl=10-10

(Atomic mass of Zn=65.39)
What is the value of logZn2+Ag+2?

E°Ag=0.80 VE°Zn=-0.76 V

Find the number of moles of Ag formed.

HARD
IMPORTANT

A cell, Ag|A g + C u 2+ |Cu, initially contains 1 M A g +  and 1   MC u 2+ ions.

Calculate the change in the cell potential after the passage of 9.65 A of current for 1 h.

HARD
IMPORTANT

An excess of liquid mercury is added to an acidified solution of   1.0× 10 3 MF e 3+ .  It is found that 5% of   F e 3+  remains at equilibrium at   25°C . Calculate   E H g 2 2 + | Hg e o , assuming that the only reaction that occurs is

  2Hg+2F e 3+ H g 2 2+ +2F e 2+ .

(Given   E F e 3+ | F e 2+ o =0.77V.)

MEDIUM
IMPORTANT

What will be the emf of the given cell   Pt | H 2 (P 1 ) | H + (aq) | H 2 (P 2 ) | Pt ?

MEDIUM
IMPORTANT

The reduction potential of hydrogen electrode at 25°C in a neutral solution is PH2=1 atm

MEDIUM
IMPORTANT

A hydrogen electrode is made by dipping platinum wire in a solution of nitric acid of pH=9 and passing hydrogen gas around the platinum wire at 1.2 atm pressure. The oxidation potential of such an electrode equals_______ V.

HARD
IMPORTANT

At 25°C, the standard reduction potential for the cell reaction

Zn(s)+2H+(aq)Zn2+(aq)+H2( g)

is 0.28 V. What is the reduction potential of the cell reaction in 10 M H+ concentration, assuming all other species to be at unit concentration? [Universal gas constant, R=8.314 J K-1 mol-1; Faraday constant, F=96500Cmol-1]

HARD
IMPORTANT

In a cell that utilizes the reaction
Zn(s)+ 2H + (aq) Zn 2+ (aq)+ H 2 (g)
addition of H2SO4 to cathode compartment,

HARD
IMPORTANT

Which of the following expression(s) represent the voltage of cell at 298 K?

Ag (s)|AgI (saturated solution) Ag2C2O4 (saturated solution) |Ag (s)

HARD
IMPORTANT

For the electrochemical cell shown below

Pt|H2p=1 atm|H+aq.,xM|Cu2+aq,1.0 MCus

The potential is 0.49 V at 298 K. The pH of the solution is closest to [ Given, standard reduction potential, E° for Cu2+/Cu is 0.34 VGas constant, R is 8.31 J K-1 mol-1 Faraday constant, F is 9.65×104JV-1 mol-1 ]

MEDIUM
IMPORTANT

At 298 K, the EMF of the given cell is

Zn(s)ZnSO4(0.1M)ZnSO4(1M)Zn(s)

MEDIUM
IMPORTANT

Calculate the pH of the following half cell:
Pt,H2H2SO4
(Given the oxidation electrode potential of the half cell is +0.3 V )