Mercuric oxide dry-cell batteries are often used where a high-energy density is
ID: 854750 • Letter: M
Question
Mercuric oxide dry-cell batteries are often used where a high-energy density is required, such as in watches and cameras. The two half-cell reactions that occur in the battery are
HgO(s)+H2O(l)+2e??Hg(l)+2OH?(aq)Zn(s)+2OH?(aq)?ZnO(s)+H2O(l)+2e?.
Part A
Write the overall cell reaction.
Express your answer as a chemical equation. Identify all of the phases in your answer.
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Part B
The value of E?red for the cathode reaction is +0.098 V. The overall cell potential is +1.35 V. Assuming that both half-cells operate under standard conditions, what is the standard reduction potential for the anode reaction?
Mercuric oxide dry-cell batteries are often used where a high-energy density is required, such as in watches and cameras. The two half-cell reactions that occur in the battery are
HgO(s)+H2O(l)+2e??Hg(l)+2OH?(aq)Zn(s)+2OH?(aq)?ZnO(s)+H2O(l)+2e?.
Part A
Write the overall cell reaction.
Express your answer as a chemical equation. Identify all of the phases in your answer.
SubmitMy AnswersGive Up
Part B
The value of E?red for the cathode reaction is +0.098 V. The overall cell potential is +1.35 V. Assuming that both half-cells operate under standard conditions, what is the standard reduction potential for the anode reaction?
Explanation / Answer
Cell reactions
HgO(S) +H2O + 2e--------------------------> Hg(l)+ 2OH-(aq) at Cathode
Zn(s) + 2OH-(aq) ----------------------------> ZnO(s) + H2O + 2e- at Anode
-----------------------------------------------------------------------------------------
Overall cell reaction HgO(s) +Zn(s) --------------------> Hg(l) + ZnO (s)
E0cell = Reduction potential of cathode(E0cathode ) - reduction potential of anode(E0anode)
Therefore,
Reduction potential of the Anode (E0anode)= Reduction potential of cathode(E0cathode ) - Ecell
= 0.098V-1.35
= -1.252V