Thermodynamics of Cell

IMPORTANT

Thermodynamics of Cell: Overview

This topic covers concepts, such as, Relation between Equilibrium Constant and EMF of a Cell, Work Done by a Cell & Relation between Gibbs Free Energy and EMF of a Cell etc.

Important Questions on Thermodynamics of Cell

MEDIUM
IMPORTANT

The relation among the cell constant, the resistance of the solution in the cell and the conductivity of the solution is

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

Zinc granules are added in excess to a 500 mL of 1.0 M nickel nitrate solution at   25°C  until the equilibrium is reached. If the standard reduction potential of  Zn2+/Zn  and  Ni2+/Ni  are  0.75  V  and  0.24  V  respectively, the concentration of  Ni2+  in solution at equilibrium.

HARD
IMPORTANT

The standard reduction potential at   25°C of the reaction,   2 H 2 O+2 e H 2 +2O H is0.8277V.  The equilibrium constant for the reaction   2 H 2 O H 3 O + +O H  at   25°C.

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 ) 0 ,  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+ ) 0 =0.77V) :

HARD
IMPORTANT

Copper sulphate solution (250 mL) was electrolysed using a platinum anode and a copper cathode. A constant current of 2 mA was passed for 16 minutes. It was found that after electrolysis the absorbance of the solution was reduced to 50% of its original value. The concentration of copper sulphate in the solution at the beginning would be:

EASY
IMPORTANT

What is the equilibrium constant for the reaction,  2Fe3++3I2Fe2++I3, if the standard reduction potentials in acidic conditions are 0.77 V and 0.54 V for  Fe3+Fe2+ and I3I couples, respectively?

HARD
IMPORTANT

The equilibrium constant for the reaction would be:

Feaq2++Ceaq3+Ceaq2++Feaq3+ Given that ECe3+/Ce2+o=1.44V, EFe3+/Fe2+o=0.68V

HARD
IMPORTANT

Find the equilibrium constant for the reaction,

  Cu 2 + + In 2 + Cu + + In 3 +

Given  ECu2+/Cu+o=0.15V, EIn2+/In+o=-0.40V, EIn3+/In+o=-0.42V

HARD
IMPORTANT

For the reaction

Agaq++Claq-AgCls

Given:

Species Gf(kJ mol-1)
Ag+aq +77
Cl-aq -129
AgCls -109

Calculate   at298K.

ΔGreaco  represent the reaction as cell calculate Ecello & find  log10 Ksp for  AgCl.

HARD
IMPORTANT

The Edison storage cell is represented as:

 Fe(s)|FeO(s)|KOH(aq)|Ni2O3(s)|Ni(s)

The half-cell reactions are:

 Ni2O3(s)+H2O(l)+2e2NiO(s)+2OHaq-;                                                                                                  E°=+0.40 VFeO(s)+H2O(l)+2eFe(s)+2OHaq-;                                                                                                   E°=0.87 V

The cell e.m.f. and the maximum amount of electrical energy that can be obtained from one mole of Ni2O3?

MEDIUM
IMPORTANT

The density of copper is  8.94 g ml1.  The number of coulombs needed to plate an area   10cm×10cm  to a thickness  102 cm using CuSO4 solution as electrolyte are:

HARD
IMPORTANT

The rusting of iron takes place as follows
2Haq++2e+12O2gH2Ol;E°=+1.23V
Feaq2++2e Fe(s) ;E°=0.44 V

Calculate  ΔG°for the net process:

HARD
IMPORTANT

The emf of the cell

Zn/Z n 2+ ( 0.01 )||F e 2+ ( 0.001M )/Fe at 298 K is 0.2905 then the value of equilibrium  constant for the cell reaction is

 

HARD
IMPORTANT

Standard electrode potential data are useful for understanding the suitability of an oxidant in a redox titration. Some half cell reactions and their standard potentials are given below:

MnO4-aq+8H+aq+5e-Mn2+aq+4H2Ol ; Eo=1.51V

Cr2O72-aq+14H+aq+6e-2Cr3+ aq+7H2Ol ; Eo=1.38V

Fe3+aq+e-Fe2+aq ; Eo=0.77V

Cl2g+2e-2Cl-aq ; Eo=1.41V

Identify the only incorrect statement regarding the quantitative estimation of aqueous FeNO32.

MEDIUM
IMPORTANT

The standard reduction potential of TiO2+ and Ti3+ are given by

TiO2++2H++e-Ti3+      Eo=0.10V

Ti3++3e-Ti      Eo=-1.21 V

Find the magnitude of standard reduction potential of TiO2+ to Ti(Round off to the nearest integer)

HARD
IMPORTANT

The correct option(s) about entropy (S) is(are)

[R= gas constant, F= Faraday constant, T= Temperature]

HARD
IMPORTANT

The reduction potential E0, in V of MnO4-aq/Mns is

[Given: EMnO4-aq/MnO2so=1.68 V; EMnO2s/Mn2+aqo=1.21 V;  EMn2+aq/Mnso=-1.03 V]

Truncate/round-off the value to TWO decimal places.

HARD
IMPORTANT

The voltage of the cell: PbPbSO4Na2SO4·10H2O (salt) Hg2SO4Hg is +0.9647 at 25°C. The temperature coefficient is 1.74×10-4 V K-1. Calculate the value of ΔS cal mol-1 K-1.

EASY
IMPORTANT

The reaction is spontaneous if the cell potential is _____.(Positive/Negative)