Title DPP 9 Solutions.pdf ✅

Class : XIIth Subject : CHEMISTRY Date : DPP No. : 9 1 (c) 1 mole of monovalent metal ion means charge of N electrons i.e., 96500 C or 1 faraday. 2 (a) For strong electrolytes Λ vs c plots are straight line. 3 (d) The metal should be capable of adsorbing H (e.g., Pt). 4 (b) Laws of electrolysis were proposed by Michael Faraday in 1833. 1. Faraday’s first law “The mass of any substance deposited or liberated at any electrode is directly proportional to the quantity of electricity passed”. i.e., w ∝ Q where, w = mass of ions liberated in gram Q = quantity of electricity passed in coulombs. 2. Faraday’s second law “When the same quantity of electricity is passed through different electrolytes, the masses of different ions liberated at the electrodes are directly proportional to their chemical equivalents.” i.e., w1 w2 = E1 E2 or Z1it Z2it = E1 E2 . 5 (d) Strong electropositive metals (I group, II group and Al) cannot be obtained at cathode by electrolysing their aqueous salt solutions. 6 (b) Weight of Cu Weight of H2 = Eq.wt.of Cu Eq.wt.of H2 Weight of Cu 0.504 = 63.6/2 1 ∴ Weight of Cu = 15.9 g 7 (b) In presence of Hg electrode preferential discharge of Na + (in comparison to H +) occurs. Topic :- Electro Chemistry Solutions
8 (b) Specific conductivity of a solution decreases with dilution. 9 (b) Passage of current in electrolytic solution is due to migration of ions towards opposite electrodes. 10 (c) Ecell = EOPL + ERPR = ― ERPL + ERPR . 11 (a) E° = E, when [Zn 2+] = 1M; Also process is Zn 2+(aq) +2e ⟶Zn(s). 12 (d) AgI (s) + e ― ⇌ Ag (s) + I ― ; E ° = 0.152 V Ag (s)⟶ Ag+ + e ― E ° = - 0.8 V AgI (s)⟶ Ag+ + I ― E ° = - 0.952 E ° cell = 0.059 n logKsp ―0.952 = 0.059 1 logKsp logKsp = ―0.952 0.059 = ― 16.135 13 (a) Λ∞ CH3COOH = Λ∞ CH3COONa + Λ∞ HCl ― Λ∞ NaCl 14 (a) At cathode : Cu 2+ + 2e ⟶Cu; At anode : Cu ⟶Cu 2+ +2e 15 (d) Wt.of Cu deposited Wt.of H2 produced = eq.wt.of Cu eq.wt.of H 0.16 wt.of H2 = 64/2 1 = 32 1 Wt. of H2 = 0.16 32 = 5 × 10―3 g Volume of H2 liberated at STP = 22400 2 × 5 × 10―3 cc = 56 cc 16 (a) Faraday’s laws are independent of external factors. 17 (a) E ° OP for Li is more, Li ⟶Li + + e Thus, Li is strong oxidant. 18 (d) All are electrolytic cells.
19 (a) 96500 C or 1F will liberate 1 eq. of O2 or 1/4 mole O2 or 5.6 litre O2 at NTP. 20 (a) 96500C or 1 Faraday charge is required for the deposition of 1 g-equivalent of a substance. ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. C A D B D B B B B C Q. 11 12 13 14 15 16 17 18 19 20 A. A D A A D A A D A A