According to the balanced equation below, how many moles of ClO2(aq) are needed to react completely with 20. mL of 0.20 M KMnO4 solution?

2H2O(l)+4MnO4(aq)+3ClO2(aq)4MnO2(s)+3ClO4(aq)+4OH(aq)

1 Answer
Dec 18, 2016

3mmol chlorite anion are required.

Explanation:

Reduction
MnO4+4H++3eMnO2(s)+2H2O(l) (i)

Oxidation
ClO2+2H2OClO4+4H++4e (ii)

Overall 4×(i)+3×(ii)
4MnO4+3ClO2+4H+4MnO2(s)+3ClO4+2H2O(l)

Moles of KMnO4=20×103L×0.20molL1=4.0×103mol

Given the equation, we need 3/4 equiv of chlorite anion,

34×4.0×103mol

What would you observe in this reaction? What was the macroscopic colour change?