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Electrochemistry Galvanic Cell Question - Come on you know you want to answer this. You totally do.?
What is the overall cell reaction?
(A) Zn^2+ + 2H2O --> Zn + H2O2 + 2H+
(B) Zn + H2O2 + 2H+ ---> Zn^2+ + 2H2O
(C) Zn + H2O2 + 2H+ + 4e- ---> Zn^2+ + 2H2O
(D) Zn^2+ + H2O2 ---> Zn + H2O + ½ O2
I know what the correct answer is but I am clueless as to why its the correct answer.
I worked it out and circled choice (B) but the answer key said no, that's completely wrong.
If anyone is willing to give this problem a go and answer with a choice and MOST importantly and complete and detailed explanation as to the reasoning behind the answer I would be MOST appreciative.
Thank you guys for taking the time to do this.
3 Answers
- JanLv 77 years agoFavorite Answer
it should be (B), because Etot = 2.54 V > 0
and spontaneous reaction...
***
(A) Etot = -1.02 V < 0
and not spontaneous reaction
***
(C) as (B), but not balanced
***
edit: yes it's possible with (D), because:
4H2O => 2H2O2 + 4H^+ + 4e^-, E1=-1.76 V
O2 + 2H2O + 4e^- => 4OH^-, E2=0.4 V
*****so total****
2H2O + O2 => 2H2O2, E (1+2)= -1.36 V
H2O2 => H2O + 0.5O2, E rev = +1.36 V > 0
***
***
Zn^2+/Zn is red, E=-0.76 V
H2O2/O2 is ox, E=1.36 V
E(tot) = 0.6 V =>
(D) is a spontaneous reaction
- Adam HessLv 47 years ago
Get this you guys....the answer key says it's (D)....where the hell does the oxygen come from? I'm beginning to wonder if the answer key could possibly be (dare I say it)...wrong? Is there anyway you guys can see it being (D)?? I simply can't :-/
