Question

An equal volume of a reducing agent is titrated separately with 1M KMnO₄ in acid, neutral and alkaline medium. The volumes of KMnO₄ required are 20 mL in acid, 33.3 mL in neutral and 100 mL in alkaline media. Find out the oxidation state of manganese in each reduction product. Give the balanced equations for all the three half reaction. Find out the volume of 1M K₂Cr₂O₇ consumed, if the same volume of the reducing agent is titrated in acid medium.

Answer 1

Let V mL of reducing agent be used for KMnO₄ in different medium which act as oxidant

Therefore, different oxidation states of Mn are :

Acid media Mn⁷⁺ + 5e^- → Mn^a+

(It is important to note that the conditions are valid only when Mn in each medium exist as monomeric atom, ie, not as Mn₂)