1.Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.
2. Calculate the emf of the cell in which the following reaction takes place:
Ni + 2 Ag(+) (0.002 M)= Ni(+2) (0.160 M)+ 2Ag Given that Eo = 1.05 V
3:The cell in which the following reactions occurs:
2Fe(+3) + 2I(-) = 2Fe(+2) + I2 Eo = 0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.
4:Why does the conductivity of a solution decrease with dilution?
5: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 λ °(HCOO−) = 54.6 S cm2 mol C = 0.025 mol L−1
6:If a current of 0.5 ampere flowsthrough a metallic wire for 2 hours, then how many electrons would flow through the wire?
7:What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O7(-2) to Cr(+3).
8:Write the chemistry of rechargingthe lead storage battery, highlighting all the materials that are involved during recharging.
9:Suggest two materials other than hydrogen that can be used as fuels in fuel cells.Ans - Methane and methanol can be used as fuels in fuel cells.
10:Calculate the standard cellpotentials of galvanic cells in which the following reactions take place: 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd (ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)
Eo (Cr) = 0.74 V , Eo(Cd) = -0.40 Calculate the ΔrGθ and equilibrium constant of the reactions (
11:Write the Nernst equation and emfof the following cells at 298 K:
(i) Sn(s) | Sn2+(0.050 M) ||H+(0.020 M) | H2(g) (1 bar) | Pt(s)
(iii) Pt(s) | Br2(l) |Br−(0.010 M) || H+(0.030 M) | H2(g) (1 bar) |Pt(s).
12:In the button cells widely used in watches and other devices the following reaction takes place:
Zn(s) + Ag2O(s) + H2O(l) → Zn2+(aq) + 2Ag(s) + 2OH−(aq) Determine Gibbs energy for the reaction
13:Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.
14:The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 Scm−1. Calculate its molar conductivity.Given, κ = 0.0248 S cm−1 c = 0.20
Calculate for all concentrations and draw aplot between and c½. Find the value of.
15:Conductivity of 0.00241 M acetic acid is 7.896 × 10−5 S cm−1. Calculate its molar conductivity and if molar conductivity at infinite dilution for acetic acid is 390.5 S cm2 mol−1, what is its dissociation constant?
Given,κ = 7.896 × 10−5 S m−1 c = 0.00241 mol L−1
16: How much electricity in terms ofFaraday is required to produce
(i) 20.0 g of Ca from molten CaCl2. (ii) 40.0 g of Al from molten Al2O3.
17:A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?
18: Three electrolytic cells A,B,Ccontaining solutions of ZnSO4, AgNO3 and CuSO4,respectively are connected in series. A steady current of 1.5 amperes was passed through them until 1.45 g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?
19:Predict the products ofelectrolysis in each of the following:
(i) An aqueous solution of AgNO3with silver electrodes.
(ii) An aqueous solution of AgNO3with platinumelectrodes.
(iii) A dilute solution of H2SO4withplatinum electrodes.
(iv) An aqueous solution of CuCl2 with platinumelectrodes.
20. What is meant by Fuel cell ? Also give itsreactions?
21.The conductivity of 0.001 M Acetic acid is 4.95 x 10-5 S cm- . Calculate the dissociation constant. If molar conductivity for acetic acid at infinite dilution is 390.5 S cm2 mol-1 .
22.The conductivity of saturated soln of AgCl at 288K is found to be 1.382 x 10-6 S cm- . Find its solubility . Given ionic conductances of Ag+ & Cl- at infinite dilution are 61.9 , 76.3 S cm2 mol-
23 .Find the charge in Coulombs on 1 g-ion of N-3.