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Topic: Mole concept related doubt  (Read 18468 times)

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Offline xstrae

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Mole concept related doubt
« on: June 15, 2006, 11:58:25 AM »
How many moles of KMnO4 will be needed to react with one mole of sulphite ion in acidic solution?
Can someone please guide me with the equation?
Thanks!
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Offline Dan

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Re: Mole concept related doubt
« Reply #1 on: June 15, 2006, 12:57:43 PM »
balanced equation
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Offline xstrae

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Re: Mole concept related doubt
« Reply #2 on: June 16, 2006, 10:43:47 AM »
u mean like this?

2 KMnO4 + 3H2SO3 ----> K2SO3 + 2MnSO3 + 3H2O + 5(O)

This indicates that number of moles of KMnO4 required is 2/3. However the book i got this question from says that the right answer is 2/5. Can u please explain if what i did is right?
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Offline Borek

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Re: Mole concept related doubt
« Reply #3 on: June 16, 2006, 10:54:33 AM »
Sulfite was meant to react, but in your equation it is spectator.
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Offline xstrae

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Re: Mole concept related doubt
« Reply #4 on: June 16, 2006, 11:07:31 AM »
allright i have no clue. can u tell me how it should react? and how many moles of KMnO4 are needed?
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Offline Borek

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Re: Mole concept related doubt
« Reply #5 on: June 16, 2006, 11:16:53 AM »
Main products are Mn2+ and SO42-.
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Offline xstrae

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Re: Mole concept related doubt
« Reply #6 on: June 17, 2006, 10:58:07 AM »
i am sorry i still dont understand. can u please explain this? i am not very good at chemistry.
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Offline Borek

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Re: Mole concept related doubt
« Reply #7 on: June 17, 2006, 12:00:29 PM »
Balance your reactions assuming MnO4- + SO32- reactants and Mn2+ + SO42- products.

Check this out: balancing redox reactions with half-reaction method.
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Offline xstrae

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Re: Mole concept related doubt
« Reply #8 on: June 19, 2006, 11:51:02 AM »
thanks a lot! i finally understood it. u rock!
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Offline xstrae

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Re: Mole concept related doubt
« Reply #9 on: June 22, 2006, 12:00:07 PM »
hey i read all the solubility rules and i think i got it. But this new problem stumps me.
 How many moles of KMnO4 will be be needed to react completely with one mole of ferrous oxalate in acidic solution???
 First of all, is ferrous oxalate soluble?if so what are the products? can u help me out once more?
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Offline xstrae

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Re: Mole concept related doubt
« Reply #10 on: June 24, 2006, 01:02:07 PM »
Is this equation right? ???

MnO4-  +Fe2+  C2O4 2-  ------->   Mn2+   +  CO2  +  Fe3+
it isnt balanced. but are the reactants and products correct?
« Last Edit: June 24, 2006, 01:12:36 PM by konichiwa2x »
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Offline Albert

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Re: Mole concept related doubt
« Reply #11 on: June 24, 2006, 01:10:18 PM »
Quote from: konichiwa2x on June 24, 2006, 01:02:07 PM
Is this equation right? ???

MnO4-  + C2O4   ------->   Mn2+   +  CO2  +  Fe3+

No, it isn't. It's not balanced and incomplete.

For example, why didn't you write iron among the reagents?
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Offline xstrae

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Re: Mole concept related doubt
« Reply #12 on: June 24, 2006, 01:13:40 PM »
ya i am sorry. i left it out accidenly. anyway, i am quite sure its still wrong. sorry, I am just a beginner in chemistry :-[. can u help me out? :-\
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Offline Albert

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Re: Mole concept related doubt
« Reply #13 on: June 24, 2006, 01:29:58 PM »
I can't, NOW ;).

In the meantime, if you know them, try writing the 3 half reactions: http://www.science.uwaterloo.ca/~cchieh/cact/c123/halfreac.html

reduction of KMnO4 (in acid)
oxidation of Fe2+
oxidation of C2O42-

Then, I'll be pleased to help you.  :)
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Offline xstrae

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Re: Mole concept related doubt
« Reply #14 on: June 24, 2006, 02:37:53 PM »
ok i think i finally worked out the equation. I think its wrong though. anyway here goes:

2MnO4- + 16H+ + 5C2O42 ----> 10CO2 + 2Mn2+ + 8H2O

do i just add a fe2+ to the reactants and fe3+ to the product side and balnce it? the question is really stupid isnt it? :( i suck at chemistry.
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