Question

The standard half-cell reactions of lead acid battery is: 2) ЕФN Half-cell reduction reaction form: red PbOo2.(s) 4H+ + so2 4, (aq) PbSO4,()+2H20 Red 2e 1.69 Рo) + So?- 4.(aq) -Ox -0.36 Pbs04.(s)2e Pb()PbO2,(s)+ 2H2SO4,(ag) 2P6SO4.(6) +2H20D 2.05 Tot. a) Determine the full cell reaction of lead acid batter and the total cell potential when discharging the battery b) The half-cell potentials are given according to a reference potential. Describe this reference potential. What is the point of a reference potential?

Answer 1

Lead-acid battery is made up of lead-acid galvanic cells which are orderly arranged in a series. The chemical conversion here is chemical energy to electrical energy. Discharging these types of batteries are spontaneous redox reactions.

A single lead acid cell discharging produces about 2 Volts.

Lead -acid galvanic cells are rechargeable. Recharging a lead-acid galvanic cell is a non-spontaneous reaction and here electrical energy gets converted into chemical energy.

The given below diagram shows a lead-acid galvanic cell during discharge.

Anodic and cathodic reactions are shown below.

anode(-) e o cathode (+) 7 leaddio rude (PbO2) lead 7 electrolyte sulfuric and intro

At anode during discharge: head is onidised at the anode: Pb (s) Pb2 (aq) + aé Pb 2+ reacts with son 2- from the sulfuric and to produce Pbson and will precipitale: 2. + Pbt som - Pbsoh (s) (9) 20) Pbson (s) will get deposited at the anode. Overall reachons at anode will be Pb (s) + son coas) PbSO4(s) + Bé At cathode during discharge Lead in the lead drosude is reduced at the Co thode by using the prolons in the sulmoic acad. PbO₂ (s) + 4H+ (aq) + aé Pb2 Coa) + 2H2O

- Pb 2+ reacts with son ²- in sulkoic and. Pbson (s) here also precipitates at the lead frame of cothode . ph 2tas) + sout cag) ~ Pbson (s) Overall reachan at Cothode : PbO2 + 4Htcas) + aétso 2 a pb son(s) + 2 HOC Thus reachon in overall can be : Anode geachar: Pb (s) + som? cam) > Pbsou + de Cathode reachon: PRO₂ + 4H+ +504 (ap) + ał PbSO4(s) + 216 Overall reochon: Ple) + PbO2 (3) *** *ms) tase es present thing

Anode Cathode Electsons are consumed cathode is positive Elections are produced Anode is negrahre Elections migrale from anode (-) to cathode (+) along corres connecting the electrodes . Protons , H Cag) are consumed at Hese colhode.
As the lead-acid cell discharges

1) PbSO₄ precipitates out and get deposited into the lead frame of both anode and cathode.

2) pH of the electrolyte (H₂SO₄) will decrease

A lead acid cells voltage is 2V for each cell. As cell increases voltage can also increases.