Qualification > Sciences
ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
--- Quote from: Greed444 on November 06, 2010, 02:46:00 pm ---does anyone know why some books say
1) E(std)cell = E(+ve terminal) - E(-ve terminal)
2) E(std)cell = E(right hand terminal) - E(left hand terminal)
in my class, we used the first one. but when i attempt June 2008 paper4 Q1, they used the 2nd one to get the answer. im confused :S
--- End quote ---
Usually both equations should result in the same answer, since the conventional way of drawing an electrode potential cell is to draw the positive terminal to the right.
The question however, seems to be telling us otherwise. Personally I think the marking scheme is wrong. :-[
This is the only CIE question that arose some concerns. The rest are all pretty easy and abide by the laws of electrode potential. ;)
For current to flow in the wires, the reactions in the half cells should occur. And for the reactions to occur, the standard electrode potential value MUST be positive. In this case the value is negative but still it is asking the direction for the flow of electrons. So it appears to be contradicting the rule of electrode potential. :-\
Hence the answer for this question should be +0.59V.
Nevertheless this is my theory. As a student, I may make mistakes. :-[
This is why i'll advice you to consult someone more experienced in chemistry, like your teacher. :)
moon:
Thanks a lot Deadly_King for ur effort ,explanation and advice. :) :)
Deadly_king:
--- Quote from: moon on November 07, 2010, 05:21:01 pm ---Thanks a lot Deadly_King for ur effort ,explanation and advice. :) :)
--- End quote ---
My pleasure buddy ;)
Greed444:
--- Quote from: Deadly_king on November 07, 2010, 04:35:59 pm ---Usually both equations should result in the same answer, since the conventional way of drawing an electrode potential cell is to draw the positive terminal to the right.
The question however, seems to be telling us otherwise. Personally I think the marking scheme is wrong. :-[
This is the only CIE question that arose some concerns. The rest are all pretty easy and abide by the laws of electrode potential. ;)
For current to flow in the wires, the reactions in the half cells should occur. And for the reactions to occur, the standard electrode potential value MUST be positive. In this case the value is negative but still it is asking the direction for the flow of electrons. So it appears to be contradicting the rule of electrode potential. :-\
Hence the answer for this question should be +0.59V.
Nevertheless this is my theory. As a student, I may make mistakes. :-[
This is why i'll advice you to consult someone more experienced in chemistry, like your teacher. :)
--- End quote ---
Thankyou Dk. eventhough u say that you are a student, but still your explanations and advices are like coming from a true expert :D
Deadly_king:
--- Quote from: Greed444 on November 08, 2010, 07:28:15 am ---Thankyou Dk. eventhough u say that you are a student, but still your explanations and advices are like coming from a true expert :D
--- End quote ---
Hahaha.............sorry to disappoint you but I am a student. ;)
Anyway thanks for the kind words :)
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