QUESTION 8 A concentration voltaic cell is constructed with two silver-silver ch

Question

QUESTION 8 A concentration voltaic cell is constructed with two silver-silver chloride electrodes, where the half-reaction is AgCl (s) + e- Ag (s) + C(aq) E° = +0.222 V The concentrations of chloride ion in the two compartments are 0.0122 M and 1.88 M, respectively. The cell emf isv 0.212 222 0.118 .00222 0.232 QUESTION 9 Consider an electrochemical cell based on the reaction: 2H+ (aq) + Sn (s) Sn2+ (aq) + H2 (g) Which of the following actions would not change the measured cell potential? O lowering the pH in the cathode compartment O increasing the pressure of hydrogen gas in the cathode compartment O increasing the tin () ion concentration in the anode compartment O addition of more tin metal to the anode compartment O Any of the above will change the measured cell potential

Explanation / Answer

8) The net reaction is the flow of electron(s) from a higher concentration of Cl- to a lower concentration, I.e,

Cl- (1.88 M) --à Cl- (0.0122 M)

The standard electrode potential is zero for all concentration cells. Hence,

Ecell = -2.303RT/nF*log10(0.0122/1.88) = -0.0591/n*log10(0.006489) = -0.0591/n*(-2.1878)

Here n =1 as a single electrode is used. Hence putting n =1 above gives

Ecell = 0.0591*(2.1878) = 0.129

My answer is closest to 0.118 V supplied in option C. Hence

Ans: (C) 0.118 V

9) The cathode reaction (reduction) is 2H+ + 2e- --à H2

The anode reaction (oxidation) is Sn – 2e- --à Sn2+

The reaction quotient Q = [Sn2+][H2]/[H+]2 (concentration of pure metals and liquids aren’t included).

The cell potential Ecell = E0cell – 0.0591/2*log10Q

All the options mentioned here will change the value of Q; hence the cell potential will be perturbed by change of all the parameters mentioned herein. Hence the answer is “Any of the above will change the measured cell potential.”

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