Same moles of which of the following species will require minimum amount of acidified KMnO4 for complete oxidation? 

(1) Ferrous ion

(2) Sulphide ion

(3) Oxalate ion

(4) Sulphite ion

Please solve it. Also is there any shortcut to solve this question fast.

Asked by rohitraman1115 | 22nd May, 2021, 04:13: PM

Expert Answer:

Oxidation number of Mn in KMnO4 is +7 and it is reduced to +5.
 
left parenthesis straight a right parenthesis space For space FeSO subscript 4

Fe to the power of plus 2 end exponent rightwards arrow Fe to the power of plus 3 end exponent space space space space space space space space space space left parenthesis Number space of space electrons space involved equals 1 right parenthesis
SO subscript 3 superscript negative 2 end superscript rightwards arrow SO subscript 4 superscript negative 2 space space space space end superscript space space space space space left parenthesis Number space of space electrons space involved equals 2 right parenthesis

Total space number space of space electrons space involved equals space 1 plus 2 equals 3



left parenthesis straight b right parenthesis space For space FeC subscript 2 straight O subscript 4 space space comma

Fe to the power of plus 2 end exponent rightwards arrow Fe to the power of plus 3 end exponent space space space space space space space left parenthesis Number space of space electrons space involved equals 1 right parenthesis
straight C subscript 2 straight O subscript 4 superscript negative 2 end superscript rightwards arrow space 2 CO subscript 2 space space space space left parenthesis Number space of space electrons space involved equals 2 right parenthesis
Total space number space of space electrons space involved equals 1 plus 2 equals 3


left parenthesis straight c right parenthesis space For space Fe left parenthesis NO subscript 3 right parenthesis subscript 2 space Fe to the power of plus 2 end exponent rightwards arrow Fe to the power of plus 3 end exponent space space space space space space left parenthesis Number space of space electrons space involved equals 1 right parenthesis
2 NO subscript 2 superscript minus rightwards arrow 2 NO subscript 3 superscript negative space space space end superscript space space left parenthesis Number space of space electrons space involved equals 4 right parenthesis

Total space number space of space electrons space involved equals 1 plus 4 equals 5

left parenthesis straight d right parenthesis space For space FeSO subscript 4
Fe to the power of plus 2 end exponent rightwards arrow Fe to the power of plus 3 end exponent space space space space space space space space space left parenthesis Number space of space electrons space involved equals 1 right parenthesis

Total space number space of space electrons space involved equals 1
As space FeSO subscript 4 space requires space least space number space of space electrons comma space thus space it space will space require space least space amount space of space KMnO subscript 4.

Answered by Ravi | 22nd May, 2021, 10:23: PM

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