Electrochemistry

The emf of cell Tl | Tl+ (0.001 M) | | Cu2+ (0.01 M) | Cu is 0.83 V at 298 K. It could be increased by :

1. increasing concentration of Tl+ ions
2. increasing concentration of Cu2+ ions
3. increasing concentration of both Tl+ and Cu2+ ions
4. decreasing concentration of both Tl+ and Cu2+ ions

The reaction; 12H2(g) + AgCl(s) H+(aq) + Cl-(aq) + Ag(s) occurs in which of the following galvanic cell :

1. Pt | H2(g) | HCl(soln.) | AgNO3(aq) | Ag
2. Ag | AgCl(s) | KCl(soln.) | AgNO3(aq.) | Ag
3. Pt | H2(g) | KCl(soln.) | AgCl(s) | Ag
4. Pt | H2(g) | HCl(soln.) | AgCl(s) | Ag

A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak electrolyte. If volume is doubled by adding more water at constant temperature, the molar conductivity of the cell will - [figure]

1. depend upon type of electrolyte
2. increase sharply
3. decrease sharply
4. remain same or can not be measured accurately

How can an electrochemical cell be converted into an electrolytic cell ?

1. Applying an external opposite potential greater than E0cell
2. Exchanging the electrodes at anode and cathode.
3. Applying an external opposite potential lower than E0cell
4. Reversing the flow of ions in salt bridge.

Molar ionic conductivities of divalent cation and anion are 57 S cm2 mol-1 and 73 S cm2 mol-1 respectively. The molar conductivity of solution of an electrolyte with the above cation and anion will be:

1. 187 S cm2 mol-1
2. 260 S cm2 mol-1
3. 65 S cm2 mol-1
4. 130 S cm2 mol-1

The reaction at cathode in the cells commonly used in clocks involves.

1. oxidation of Mn from +2 to +7
2. reduction of Mn from +4 to +3
3. oxidation of Mn from +3 to +4
4. reduction of Mn from +7 to +2

The quantity of silver deposited when one coulomb charge is passed through AgNO3 solution :

1. 0.1 g atom of silver
2. 1 chemical equivalent of silver
3. 1 g of silver
4. 1 electrochemical equivalent of silver

For the electrochemical cell M | M2+ || X | X2- If E0(M2+/M) = 0.46 V and E0(X/X2-) = 0.34 V. Which of the following is correct?

1. Ecell = 0.80 V
2. M + X M2+ + X2- is a spontaneous reaction
3. Ecell = -0.80 V
4. M2+ + X2- M + X is a spontaneous reaction

One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?

1. Metal ion - Metal electrodes
2. Oxidation - Reduction electrodes
3. Metal - Insoluble Salt - Anion electrodes
4. Gas - Ion electrodes

What pressure (bar) of H2 would be required to make emf of hydrogen electrode zero in pure water at 25 ?

1. 0.5
2. 10-14
3. 1
4. 10-7