In electrolysis of NaCl when Pt electrode is taken then H2 is liberated at cathode while with Hg cathode it forms sodium amalgam because
Hg is more inert than Pt
More voltage is required to reduce H+ at Hg than at Pt
Na is dissolved in Hg while it does not dissolve in Pt
Concentration of H+ ions is larger when Pt electrode is taken
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
On heating one end of a piece of a metal, the other end becomes hot because of
Energised electrons moving to the other end
Resistance of the metal
Mobility of atoms in the metal
Minor perturbation cell in the energy of atoms .
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
The efficiency of a fuel cell is given by
ΔG / ΔS
ΔG / ΔH
ΔS / ΔG
ΔH / ΔG
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
EoFe2+/Fe = -0.441 V and EoFe2+/Fe2+= 0.771V, the standard emf of the reaction Fe +2Fe3+ →3Fe 2+ will be
0.111 V
0.330 V
1.653 V
1.212 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
Standard reduction potentials at 25oC of Li+ / Li, Ba2+ / Ba, Na+ / Na and Mg2+ / Mg are -3.05, -2.90, -2.71 and -2.37 volt respectively. Which one of the following is the strongest oxidising agent?
Mg2+
Ba2+
Na+
Li+
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)
