Answer to Question #179332 in General Chemistry for allain

Question

How could you measure the rate of reaction of the titration involving Iron(ll) and KMnO4? (KMnO4 is the titrant)

Answer 1

In the reaction as iron (II) acts as the solvent, then this reactant is present in large excess, such as for instance in a hydrolysis reaction.So its concentration can be considered as constant. Thus a bimolecular hydrolysis follows a pseudo-first order kinetics, i.e. the reaction rate is mainly determined by the concentration of the reactant times the rate constant.To monitor the reaction as a function of time, KMnO4 is neutralized with iron (II) to a predefined pH value during time, i.e. by using a pH-Stat titration.The value for the rate constant is obtained from the slope of the line obtained by plotting the concentration of unreacted KMnO4 as a function of time.

Similarly, it is known that change in the temperature affects the rate constant, therefore temperature variations studies have also been carried out to study the temperature dependence of the reaction rate constant.