Suggest two materials other than hydrogen that can be used as fuels in fuel cells.
Methane and Methanol.
The positive value of the standard electrode potential of Cu+2/Cu indicates that
(a) this redox couple is a stronger reduction agent than the H/H2 couple
(b) this redox couple is a stronger oxidizing agent than H+/H2
(c) Cu can displace H2 from acid
(d) Cu cannot displace H2 from acid
Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.
Three electrolytic cells A, B, C containing solutions of ZnS04, AgNO3 and CuS04, respectively are connected in series. A steady current of 1.5 amperes was passed through them until 45 g of silver deposited at the cathode of call B. How long did the current flow? What mass of copper and zinc were deposited?
The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm-1. Calculate its molar conductivity.
Assertion (A): E , increases with increase in concentration of Ag+ ions.
Ag / Ag+
Reason (R): E + has a positive value.
Ag /Ag
How much charge is required for the following reductions:
(i) 1 mol of Al3+ to Al?
(ii) 1 mol of Cu2+ to Cu ?
(iii) 1 mol of Mn04- to Mn2+?
E °en = 1.1 V for Daniell cell. Which of the following expressions are correct description of state of equilibrium in this cell?
Write the Nemst equation for the cell reaction in the Daniell cell. How will the Ecell be affected when concentration of Zn2+ ions is increased?
Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
What will happen during the electrolysis of aqueous solution of CuSO4 in the presence of Cu electrodes?
(a) Copper will deposit at cathode.
(b) Copper will dissolve at anode.
(c) Oxygen will be released at anode.
(d) Copper will deposit at anode.
Consider the figure given below and answer the questions (i) to (vi) that follow.
(i) Redraw the diagram to show the direction of electron flow.
(ii) Is silver plate anode or cathode?
(iii)What will happen if salt bridge is removed?
(iv)When will the cell stop functioning?
(v)How will concentration of Zn+2 cell functions?
(vi)How will the concentration of Zn+2 ions and Ag+ ions be affected after the cell becomes ‘dead'?
Consultthe table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.
Use the data given in Q. 8 and find out which of the following is the strongest oxidizing agent.
The cell in which the following reaction occurs: 2Fe3+ (aq) + 2I– (aq) —> 2Fe2+ (aq) +I2 (s) has E °cell=0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.
Write the cell reaction of a lead storage battery when it is discharged. How does the density of the electrolyte change when the battery is discharged?
The molar conductivity of 0.025 mol L-1 methanoic acid is 46.1 S cm2 mol-1. Calculate its degree of dissociation and dissociation constant Given λ °(H+)=349.6 S cm2 mol-1 andλ °(HCOO-) = 54.6 S cm2 mol-1
The quantity of charge required to obtain one mole of aluminium from
Al2O3 is (a) IF (b) 6F (c) 3F (d) 2F
Aqueous copper sulphate solution and aqueous silver nitrate solution are electrolysed by 1 ampere current for 10 minutes in separate electrolytic cells. Will the mass of copper and silver deposited on the cathode be same or different? Explain your answer.
Given the standard electrode potentials, K+/K=-2. 93 V, Ag+/Ag = 0.80 V, Hg2+/Hg =0.79V, Mg2+/Mg=-2.37V, Cr3+/Cr=0.74V.
Arrange these metals in their increasing order of reducing power.
Predict the products of electrolysis in each of the following.
(i) An aqueous solution of AgNO3 with silver electrodes.
(ii) An aqueous solution of AgNO3 with platinum electrodes.
(iii) A dilute solution of H2S04 with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
Assertion (A): Copper sulphate can be stored in zinc vessel.
Reason (R): Zinc is less reactive than copper.
Assertion (A): Lm for weak electrolytes shows a sharp increase when the electrolytic solution on dilution of solution.
Electrockemistrij 63
Reason (R): For weak electrolytes dissociate partially in concentrated solution. On dilution, their degree of dissociation increases hence their Am increases sharply.
Conductivity of an electrolytic solution depends on
(b) concentration of electrolyte
(d) distance between the electrodes
Unlike dry cell, the mercury cell has a constant cell potential throughout its useful life. Why?
In an aqueous solution, how does specific conductivity of electrolytes change with addition of water?
Assertion (A): Conductivity of all electrolytes decreases on dilution.
Reason (R): On dilution number of ions per unit volume decreases.
Calculate the standard cell potentials of galvanic cell in which the following reactions take place
The resistance of a conductivity cell containing 0.001 M KCI solution at 298 K is 1500 Ω What is the cell constant if conductivity of 0.001 M KCI solution at 298 K is 0.146 x 10-3 S cm-1?
How much electricity in terms of Faraday is required to produce .
(i) 20.0 g of Ca from molten CaCl2?
(ii) 40.0 g of Al from molten Al203?
Using the data given in Q. 8, find out in which option the order of reducing power is correct.
Assertion (A): Ecell should have a positive value for the cell to function. Reason (R). Ecadlode Eanode
In the button cells widely used in watches and other devices the following reaction takes place:
In the electrolysis of aqueous sodium chloride solution, which of the half-cell reaction will occur at anode?
mean? Zn /Zn
for cell reaction ever be equal to zero?
