Electrochemistry · Question 11

Electricity is passed through an acidic solution of Cu2+ till all the Cu2+ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is mL. (Nearest integer) [Given: Cu2+(aq) + 2e- Cu(s); E red = +0.34 V O2(g) + 4H+ + 4e- 2H2O; E red = +1.23 V Molar mass of Cu = 63.54 g mol-1 Molar mass of O2 = 32 g mol-1 Faraday Constant = 96500 C mol-1 Molar volume at STP = 22.4 L]

Molar conductivity of a weak acid HQ of concentration 0.18 M was found to be 130 of the molar conductivity of another weak acid HZ with concentration of 0.02 M. If Q- happened to be equal to Z-, then the difference of the pKa values of the two weak acids (pKa(HQ) - pKa(HZ)) is (Nearest integer). [Given: degree of dissociation ( ) 1 for both weak acids, : limiting molar conductivity of ions]

In the given electrochemical cell, Ag(s)|AgCl(s)|FeCl2(aq), FeCl3(aq) | Pt(s) at 298 K, the cell potential ( Ecell) will increase when : Choose the correct answer from the options given below :

1. C, D and E Only
2. A and B Only
3. B Only
4. A and E Only

[figure] Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming M+ (M M+ + e-). The cation M+ is present in two different concentrations c1 and c2 as shown above. Which of the following statement is correct for generating a positive cell potential?

1. If c1 is present at anode, then c1 > c2.
2. If c1 is present at cathode, then c1 > c2.
3. If c1 is present at cathode, then c1 < c2.
4. If c1 is present at anode, then c1 = c2.

Consider the following electrochemical cell at 298 K Pt | HSnO2-(aq) | Sn(OH)62-(aq) | OH-(aq) | Bi2O3(s) | Bi(s). If the reaction quotient at a given time is 106, then the cell EMF ( Ecell) is 10-1 V (Nearest integer). Given the standard half-cell reduction potential as E Bi2O3/Bi,OH- = -0.44 V and E Sn(OH)62-/HSnO2-,OH- = -0.90 V

Consider the following reduction processes : Al3+ + 3e- Al(s), E0 = -1.66 V Fe3+ + e- Fe2+, E0 = +0.77 V Co3+ + e- Co2+, E0 = +1.81 V Cr3+ + 3e- Cr(s), E0 = -0.74 V The tendency to act as reducing agent decreases in the order :

1. Al > Fe2+ > Cr > Co2+
2. Al > Cr > Co2+ > Fe2+
3. Cr > Fe2+ > Al > Co2+
4. Al > Cr > Fe2+ > Co2+

Consider the following electrochemical cell : Pt | O2(g)(1 bar) | HCl(aq) || M2+(aq, 1.0 M) | M(s) The pH above which, oxygen gas would start to evolve at anode is (nearest integer). [Given : . arrayl E M2+/M = 0.994 V \ E O2/H2O = 1.23 V array \ standard reduction potential and RTF(2.303) = 0.059 V at the given condition]

The pH and conductance of a weak acid (HX) were found to be 5 and 4 10-5 S, respectively. The conductance was measured under standard condition using a cell where the electrode plates having a surface area of 1 cm2 were at a distance of 15 cm apart. The value of the limiting molar conductivity is S m2 mol-1. (nearest integer) (Given : degree of dissociation of the weak acid ( ) 1)

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K. MX(s) M+(aq) + X-(aq); Ksp = 10-10 If the standard reduction potential for M+(aq) + e- M(s) is ( E M+/M ) = 0.79 V, then the value of the standard reduction potential for the metal/metal insoluble salt electrode E X-/MX(s)/M is mV. (nearest integer) [Given: 2.303RTF = 0.059 V]