a. Potassium permanganate solutions generally decompose slowly at room temperatu

Question

a. Potassium permanganate solutions generally decompose slowly at room temperature, and the KMnO_4 concentration decreases with time from the preparation of the solution. Suppose you had left your standardized KMnO_4 solution in your locker for a week before you carried out part B of the experiment, and its concentration had decreased by 2%. What effect would this have on your determinations of the changes in oxidation numbers of the reducing agents? Explain. b. It is likely that the SnCl_2 2H_2O and the FeSO_4 7H_2O solutions have already undergone slight oxidation by reaction with dissolved oxygen in the water. Hence the concentrations written on the reagent bottles are probably slightly greater than the actual concentrations of Sn^2+ and Fe^2+, respectively. What effect will this have on the oxidation number changes you determine? Explain.

Explanation / Answer

3)a) Potassium permanganate is an oxidising agent, if we keep some period as such it oxidizes the components present in the solution losing oxygen & its oxidation number changes from +7 to =4. The oxidation number of the reducing increases as there is gain of oxygen ( gain of electrons) as per definition.

b)SnCl2is a reducing agent and as per definition Sn+2 gains the elctrons undergoing oxidation to form Sn+4 & reducing other substancemay be dissoleved oxygen.Thus change in Oxidation number of Sn from Sn2+ to Sn+4 is observed.

Similatly, Fe+2 in ferrous sulphate changes to Fe +3 ferric state during reduction. Thus change in Oxidation number of iron +2 to +3 is observed during the reaction.

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