Multiple Choice QuestionsThe relative lowering of vapour pressure of a dilute aqueous solution containing nonvolatile solute is 0.0125. The molality of the solution is about
0.70
0.50
0.90
0.80
If the elevation in boiling point of a solution of 10g of solute (mol. wt. = 100) in 100g of water is ΔTb, the ebullioscopic constant of water is
100Tb
ΔTb
10Tb
10
An alloy of Pb-Ag weighing 1.08g was dissolved in dilute HNO3 and the volume made to 100 mL. A silver electrode was dipped in the solution and the emf of the cell set up Pt(s), H2(g)|H+(1M) || Ag+(aq)|Ag(s) was 0.62V. If E°cell= 0. 80V what is the percentage of Ag in the alloy? [At 25°C, RT IF= 0.06].
50
1
10
25
The standard oxidation potentials of Zn, Cu, Ag and Ni electrodes are +0.76, 0.34, - 0.80 and +0.25 V respectively. Which of the following reaction will provide maximum voltage?
Cu + 2Ag+(aq) → Cu+2 (aq) +2Ag
Zn + 2Ag+(aq) → Zn2+(aq) + 2Ag
H2 + Ni2+ (aq) → 2H+(aq) + Ni
Zn + Cu2+(aq) → Zn2+(aq) + Cu
A.
Cu + 2Ag+(aq) → Cu+2 (aq) +2Ag
Standard oxidation potentials of Zn, Cu, Ag and Ni electrode are + 0.76,- 0.34, - 0.80 and + 0.25V respectively. (Given)
Zn+2 + 2e- → Zn, Ecell = -0.76V
Cu+2 + 2e- → Cu, Ecell = + 0.34V
Ag+ + e- → Ag, Ecell = +0.80V
Ni2+ + 2e- → Ni, Ecell = -0.25V
(a) Cu + 2Ag+(aq) → Cu+2 (aq) +2Ag
E°cell = E°cathode - E°anode
E°cell = 0.80- 0.34 = 0.46V
(b) Zn + 2Ag+(aq)
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