What is true in the galvanic cell in which the overall reaction is Mg(s) + Br_2(

Question

What is true in the galvanic cell in which the overall reaction is Mg(s) + Br_2(l) rightarrow Mg^2+ (aq) + 2Br^- (aq) The Br_2 | Br^- electrode is the anode. cations ions migrate towards the cathode. An increase in concentration of Mg^2+ would increase the cell voltage. The electrons enter the magnesium electrode from the external circuit. Calculate the potential of a voltaic cell in which the |Zn^2+| is 0.10 M and |Cu^2+| is 0.010 M (T = 25 degree C). 0.38 V 0.44 V 1.07 V 1.13V A solution of CdSO_4 is electrolyzed between inert electrodes. How many hours must a current of 1.75 A flow to deposit 11.8 cadmium? 0.51 1.26 3 22 5.18

Explanation / Answer

(6)

b. cations migrate towards cathode because, the following half reactions are occured based on the given overall reaction,

At anode: Mg(s) ----------> Mg2+ (aq.) + 2e

At Cathode: Br2 (l) + 2 e ----------> 2 Br - (aq.)

Applying Nernst equation to the overall cell reaction,

Ecell = E0cell - (RT/nF) ln [Br -][Mg2+]

(a) is wrong becase it acts cathode

(c) is wrong increase in [Mg2+] will decrease cell potential (observe Nernst equation)

(d) is wrong becuase electrons are given to electrode during the oxidation these can enter at cathode through external circuit.

Only (b) is right because as Br2 reduces to Br - at cathode compartment to balance the charge, cations will migrate towards cathode.

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