Reduction potential for the following half-cell reactions are
+ 0.32 V
- 0.32 V
+ 1.20 V
- 1.20 V
Which one of the following pairs of substances on reaction will not evolve H2 gas?
Iron and H2SO4 (aqueous)
Iron and Steam
Copper and HCl (aqueous)
Sodium and Ethyl alcohol
The most convenient method to protect the bottom of the ship made of iron is
Coating it with red lead oxide
White tin plating
Connecting it with Mg block
Connecting it with Pb block
A hypothetical electrochemical cell is shown below
A | A+ (xM) || B+ (yM) | B
The emf measured is + 0.20 V. The cell reaction is
A + B+ → A+ + B
A+ + B → A + B+
A+ + e- → A; B+ + e- → B
The cell reaction cannot be predicted
The specific conductance of a 0.1 N KCl solution at 23o C is 0.012 ohm-1 cm-1. The resistance of cell containing the solution at the same temperature was found to be 55 ohm. The cell constant will be
0.142 cm-1
0.66 cm-1
0.918 cm-1
1.12 cm-1
Cu+ (aq) is unstable in solution and undergoes simultaneous oxidation and reduction according to the reaction
- 0.38 V
+ 0.49 V
+ 0.38 V
- 0.19 V
Equivalent conductance of NaCl, HCl and C2H5COONa at infinite dilution are 126.45, 426.16 and 91 ohm-1 cm2, respectively. The equivalent conductance of C2H5COOH is
201.28 ohm-1 cm2
390.71 ohm-1 cm2
698.28 ohm-1 cm2
540.48 ohm-1 cm2
An electrochemical cell is shown below
Pt, H2 (1 atm) |HCl (0.1 M)| CH3COOH(0.1 M)| H2 (1 atm), Pt. the emf of the cell will not be zero, because
emf depends on molarities of acids used
pH of 0.1 M HCl and 0.1 M CH3COOH is not same
The temperature is constant
Acids used in two compartments are different
For the cell reaction,
Cu2+ (C1, aq) + Zn (s) Zn2+ (C2, aq) + Cu (s) of an electrochemical cell, the change in free energy (ΔG) at a given temperature is a function of
In (C1)
In (C2/ C1)
In (C2)
In (C1 + C2)
Standard electrode potentials are
Fe2+ / Fe, Eo = - 0.44 V
Fe3+ / Fe2+ , Eo = 0.77 V
Fe2+, Fe3+ and Fe block are kept together, then
Fe3+ increases
Fe3+ decreases
Fe2+/Fe3+ remains unchanged
Fe2+ decreases
