Simultaneous Estimation of Mn and Cr In a solution of KMnO4 and K2Cr2O7

AIM

Estimation of Mn and Cr in a solution of KMnO4 and K2Cr2O7.

APPARATUS REQUIRED

Clorimetry,100cc standard flasks, beakers, pipette and cuvette.

PRINCIPLE

Optical density of the mixture containing m compound is measured at  M suitable choosen  λ and n simultaneously.Equations are set suppose Ca and Cb are the concentrations of two compounds of a binary mixture and Dab1 and Dab2 are its optical density at 1 and 2.

If Da1 and Da2 are the optical densities of pure A of concentration Ca1 and Cb1 those of pure B of concentration Ca1 and Cb1 those of pure B of concentration Cb1 then assuming  Beers law to be valid ,we have optical densities of mixture to be

Dab(1) =  Da(1) Ca/C’a  +  Db(1)Cb/C’b………………………….(1)

Dab(2) = Da(2) Ca/C’a   + Db(2)Cb/C’b………………………….(2)

Thus the measurement of O.D (optical density) of the mixture and the solution of pure component of KMnO4 concentration at suitable choosen λ enable to calculate Ca and Cb.

PROCEDURE

Prepare 100ml each of 0.001N K2Cr2O7 and 0.001N KMnO4 in 0.5ml H2SO4.Find the optical density of the solution .Da and Db for  the available λ .Then find the ratio of Da/Db.

Select the optimum λ corresponding to minimum and maximum of Da/Db. Measure the O.D(optical density) of given concentration of KMnO4 and K2Cr2O7 using equation 1 and 2.

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