Electrochemistry

The standard reduction potentials at 298 K for the following half cells are given below : Cr2O72- + 14H+ + 6e- 2Cr3+ + 7H2O, E = 1.33 V Fe3+(aq) + 3e- Fe E = -0.04 V Ni2+(aq) + 2e- Ni E = -0.25 V Ag+(aq) + e- Ag E = 0.80 V Au3+(aq) + 3e- Au E = 1.40 V Consider the given electrochemical reactions, The number of metal(s) which will be oxidized by Cr2O72-, in aqueous solution is .

Match List I with List II Choose the correct answer from the options given below:

1. A-III, B-I, C-IV, D-II
2. A-I, B-II, C-III, D-IV
3. A-IV, B-III, C-I, D-II
4. A-II, B-III, C-IV, D-I

Which out of the following is a correct equation to show change in molar conductivity with respect to concentration for a weak electrolyte, if the symbols carry their usual meaning :

1. m - m + AC 12 = 0
2. m2C + Ka m 2 - Ka m m = 0
3. m - m - AC 12 = 0
4. m2C - Ka m 2 + Ka m m = 0

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