Consultthe table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.
Oxidation of Fe2+ converts it to Fe3+, i.e.,Fe2+ –>Fe3+ +e– ; E °ox= – 0.77 V Only those substances can oxidise Fe2+ to Fe3+ which are stronger oxidizing agents and have positive reduction potentials greater than 0.77 V, so that EMF of the cell reaction is positive. This is so for elements lying below Fe3+/Fe2+ in the series ex: Br2, Cl2 and F2.
Consider a cell given below:
Cu |Cu2+ || Cl |Cl2, Pt
Write the reactions that occur at anode and cathode.
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.
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?
Assertion (A): Mercury cell does not give steady potential.
Reason (R): In the cell reaction, ions are not involved in solution.
Value of standard electrode potential for the oxidation of Cl ions is more positive than that of water, even then in the electrolysis of aqueous sodium chloride, why is Cl- oxidized at anode instead of water?
Assertion (A): Current stops flowing when Ecell = 0.
Reason (R): Equilibrium of the cell reaction is attained.
Assertion (A): Conductivity of all electrolytes decreases on dilution.
Reason (R): On dilution number of ions per unit volume decreases.
When acidulated water (dil. H2SO4 solution) is electrolysed, will the pH of the solution be affected? Justify your answer.
If a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons would flow through the wire?
Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
Conductivity of 0.00241 M acetic acid is 7.896 x 10-5 S cm-1. Calculate its molar conductivity. If Λm0, for acetic acid is 390.5 S cm2 mol-1, what is its dissociation constant?
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+?
What will happen during the electrolysis of aqueous solution of CuSO4 by using platinum electrodes?
(a) Copper will deposit at cathode.
(b) Copper will deposit at anode.
(c) Oxygen will be released at anode.
(d) Copper will dissolve at anode.
In an aqueous solution, how does specific conductivity of electrolytes change with addition of water?
Which reference electrode is used to measure the electrode potential of other electrodes?
Why on dilution the Am of CH3COOH increases drastically, while that of CH4COONa increases gradually?
Assertion (A): Ecell should have a positive value for the cell to function. Reason (R). Ecadlode Eanode
Assertion (A): Lm for weak electrolytes shows a sharp increase when the electrolytic solution on dilution of solution.
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Reason (R): For weak electrolytes dissociate partially in concentrated solution. On dilution, their degree of dissociation increases hence their Am increases sharply.
Assertion (A): For measuring resistance of an ionic solution an AC source is used.
Reason (R): Concentration of ionic solution will change if DC source is used.
Consider the reaction: Cr2O72--+ 14H+ + 6e- -> 2Cr3+ + 7H2O What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72- ?
Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.
Arrange the following metals in the order in which they displace each other from the solution of their salts: Al, Cu, Fe, Mg and Zn.
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.
The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm-1. Calculate its molar conductivity.
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?
The conductivity of NaCl at 298 K has been determined at different concentrations and the results are given below:
In the electrolysis of aqueous sodium chloride solution, which of the half-cell reaction will occur at anode?
Unlike dry cell, the mercury cell has a constant cell potential throughout its useful life. Why?
Solutions of two electrolytes 'A' and 'B' are diluted. The Am of 'B' increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Justify your answer.
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?
Assertion (A): Electrolysis of NaCl solution gives chlorine at anode instead of 02.
Reason (R): Formation of oxygen at anode requires overvoltage.
