Eo Gchem HARD
Started by silveryhair
-4.07 would be the reverse nonspontaneous reaction. The spontaneous reaction will always be positive.
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The way the OP write it is awkward, we need it to be in the form of a reaction to see whether the voltage is neg or pos.
yes it is 4.07. But why? when they dont show the equation, i dont get how to do it. Can someone explain? Thanks!
NaCl -> Na+ + Cl-
Na+ -> Na = -2.71 V
Cl -> Cl- = +1.36 V
Since Na is being oxidized E should be +2.71 V, thus,
2.71 + 1.36 = 4.07 V
below is how I did same as pooyah. But I came up with a question!
Na(+) + e(-) -> Na Eo= -2.71v
Cl2 + 2e(-) -> 2Cl(-) Eo= +1.36v
Cl2 gets reduced, so we keep it as it is.
Na gets oxidized, so we reverse the sign.
And jus add them up.
The problem says "molten NaCl that forms Cl2(g) at anode and Na(l) at cathode"
So, my question is if Cl2 is formed at ANODE, should it get oxidized? also for Na, it's formed at CATHODE, so should be reduced?
hey but i think the CL is oxidized and Na is reduced since the title says that it forms CL2 (gas) at the anode. So my equation is -2.71-1.35=-4.07, which is nonspontaneous in the direction written, and spontaneous in the reverse direction. Can somebody tells me if i am right or not? Thanks
Thats what i was thinking, and I ended up with C and its wrong.
My answer is E not C.
Exactly, that was my concern about this question.
But now I am thinking the answer is -4.07 if they asked emf?
They are just asking the theoretical voltage required? so we just ignore the sign???
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How do we know that Na is oxidized?
This problem is definitely wrong..
Eo= -4.07 v
Its an electrolytic cell so its NONspontaneous bc therefore Eo= negative
Electrolysis can not be positive
Cl- --> Cl2(g) oxidation
Cl2 gas is being formed since Cl- is forced to be oxidized
Na+ --> Na(l) reduction
Na liquid is formed since Na+ is forced to be reduced
Eo= -4.07 v
Its an electrolytic cell so its NONspontaneous bc therefore Eo= negative
Electrolysis can not be positive
Cl- --> Cl2(g) oxidation
Cl2 gas is being formed since Cl- is forced to be oxidized
Na+ --> Na(l) reduction
Na liquid is formed since Na+ is forced to be reduced
This is an example of electrolysis. since it says we get Cl2 at anode it means it's being reduced and Na at cathode means Na is being oxidized. Remember, in electrolysis we're forcing a non-spontaneous reaction to happen unlike in a galvanic cell (like a battery). In electrolysis electrons the electrons still go from the anode to the cathode but at the anode they get reduced instead of oxidized! However, I think it should give a negative number since we're forcing a non-spontaneous reaction to be spontaneous!
How can NaCl form 1 Na and 2 Cl???
you got the concept mixed!
From KAP REVIEW
"in an electrolytic cell, the anode is + and the cathode is -, but in a galvanic cell it's opposte. HOWEVER, in both types of cells, reduction occurs at the cathode and oxidation occurs at the anode"
In electrolysis you pretty much always use a molten solution, and the 2 sticks in them are Na+ and Cl-. You start with Cl- + Na+ ----> Na metal and Cl gas
And in galvanic and electrolysis, its ALWAYS going from Anode--->Cathode
BUT in electrolysis, the + is on the anode and - is on the cathode, SO the whole electrons are being forced like this: + ---electrons---> -
I think the way the op wrote the Eo is wrong
And in galvanic and electrolysis, its ALWAYS going from Anode--->Cathode
BUT in electrolysis, the + is on the anode and - is on the cathode, SO the whole electrons are being forced like this: + ---electrons---> -
I think the way the op wrote the Eo is wrong
you got it! I agree!
one question I came up for you why the answer here is not neg.
I am thinking the answer is -4.07 if they asked emf?
But, they are just asking the theoretical voltage required? so we just ignore the sign??? Stupid question??
voltage, EMF, cell potential are the same thing. Theoretical will be the maximum
well..then like you said earlier I guess there is no answer to choose from the choices..
I got +4.07. (and don't know why ppl think it's minus)
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