Answer:
The mercury button battery line notation is:
Zn⁰| Zn²|| , HgO| Hg⁰||
Explanation:
Mercury batteries either use
pure mercury(II) oxide (HgO)—which is called mercuric oxide
or a mixture of HgO with manganese dioxide (MnO2) which is as the cathode.
Anode has two half reactions:
The first step is an electrochemical reaction step:
Zn + 4OH− → Zn(OH)4−2 + 2e−[3]
cathode has a half reaction :
HgO + H2O + 2e− → Hg + 2OH−[3]
+0.0977 V standard potential is of this reaction.
which is followed by a chemical reaction step:
Anode consists of oxidation:
Zn+2OH>ZnO+H2O+2e
which gives an overall anode half-reaction of:
Zn + 2OH− → ZnO + H2O + 2e−[3]
Therefore,
The overall reaction for the battery is:
Zn + HgO → ZnO + Hg
