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Inorganic Chemistry

SAKSHI PANDEY's Avatar
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15 Nov 2009 19:57:49 IST
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Why equivalent mass of KMnO4 different in different mediums (ie acidic,basic)
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Why equivalent mass of KMnO4 different in different mediums (ie acidic,basic)


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 yamini 's Avatar

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15 Nov 2009 21:38:19 IST
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it is due to difference in number of electrons participating in reactions

KMnO4 + 8H+ + 5 electrons .........>K+ +Mn2+ +4H2O (ACIDIC MEDIUM)

KMnO4 +2H2O+3eletrons..........>K+ +4OH- +MnO2 (ALKALINE MEDIUM)

anurag kanungo's Avatar

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15 Nov 2009 21:44:32 IST
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KMnO4 has a Molar mass of 158.04 g/mol

to find its equivalent weight as an oxidizer we need to divide the Molar mass by the moles of electrons taken in its half reaction
---------------------

the less common half reaction, uses KMnO4 as an oxidizer in an basic solution:
KMnO4 (takes 3 electrons) & OH- --> MnO2 (s)

in which case your answer comes form:
158.04 g/mol divided by 3 moles of e- =
Your less commonly used answer = 52.68 grams / equivalent
-------------------

the most common half reaction, uses KMnO4 as an oxidizer in an acidic solution:
KMnO4 (takes 5 electrons) & 8 H+ --> Mn+2

in which case your answer comes form:
158.04 g/mol divided by 5 moles of e- =
Your most widely used answer = 31.61 grams / equivalent

Sagar Saxena's Avatar

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15 Nov 2009 21:49:07 IST
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hello dear

 

 

 


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6 Feb 2012 08:25:48 IST
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Why equivalent mass of KMnO4 different in different mediums (ie acidic,basic)



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