Question

Standard reduction potentials for the Zn2+/Zn and Pb2+/Pb couples are -0.76 and - 0.13 V, respectively. The galvanic cell below uses the half-cells Pb2+ Pb and Zn2+|Zn, and a salt bridge containing KCl(aq). The voltmeter gives a positive voltage reading. voltmeter salt bridge CD- <-CD-RB B The electrode B could be inert platinum metal or lead metal. O True O False

Answer 1

The electrode B could be inert platinum metal or lead metal.

The option is true.

Reason:

The electrode B is a cathode electrode used in an electrochemical cell at which reduction occurs which is denoted on the right side of the salt bridge in cell notations.

If lead metal is used as cathode:

Lead is more likely to be reduced than zinc,therefore in that pair lead will be the cathode where reduction occurs and zinc will be the anode where oxidation occurs.

Zinc metal is oxidised to Zn2+ ions at the zinc electrode(anode) and Pb2+ ions are reduced to Pb at the lead electrode(cathode).Thus there is a redox reaction taking place.

If platinum electrode is used:

Inert electrode allows the current to flow,the mass of an electrochemical cell does not change during the oxidation-reduction reaction,inert electrodes are often made of platinum or gold because these metals are chemically unreactive.Thus it makes in excellent electrode in the redox reactions occuring in electrochemical cell.

If platinum is used as cathode,there occurs a reduction half reaction in which Pb2+ is reduced to Pb and conversely oxidation half reaction occurs at anode where Zn is oxidised to Zn2+. As the electrons flow from zinc electrode, it must be electrically negative and in contrast electrons flow towards platinum electrode so it must be electrically positive.

In short

Answer: TRUE The B electrode can be platinum metal or lead metal