# Spectrophotometric Analysis of a Two-Component Mixture Essay

Words: 1878
Pages: 8

Title: Spectrophotometric analysis of a two-component mixture

Aim: i. To prepare working standards of dichromate and permanganate ii. To measure the absorbance of the prepared working standards of dichromate and permanganate using a spectrophototometer iii. To determine the concentrations of permanganate in a mixture of unknown.

Abstract:
Working standards of dichromate and permanganate were prepared and absorbance for each found. This was done in order to plot a graph of absorbance versus concentration, from which the concentration of permanganate and dichromate in the unknown sample could be determined. Sulphuric acid was added to the standards in order to force the reaction to completion. Wavelengths
Calculating the actual concentrations of KMnO4 and K2Cr207 i. K2Cr2O7

Mass of K2Cr2O7 = 5.5339 g in 1 L Molar mass of K2Cr2O7 = 294.185 g/mol Moles = 5.5339 g/294.185 g/mol = 0.018810 moles Molarity = 0.018810 moles /1 L = 0.018810 M ii. KMnO4

Mass of KMnO4 = 0.8079 g in 500 ml Molar mass of KMnO4 = 158.0339 g/mol Moles = 0.8079 g/158.0339 g/mol = 5.112 x 10-3 moles Molarity = 5.112 x 10-3 moles/0.5 L = 0.010224 M

2. Calculating concentrations of working standards Mass of K2Cr2O7 = 5.5339 g in 1 L
Molar mass of K2Cr2O7 = 294.185 g/mol
Moles = 5.5339 g/294.185 g/mol = 0.018810 moles
Moles in 2.00 ml = (0.018810 moles x 2.00 ml)/1000 ml = 3.76 x 10-5 moles
Molarity = 3.76 x 10-5 moles/0.1 L = 3.76 x 10-4 M
Following the same calculation, the molarity of the other volumes were found:
In 4.00 ml = 7.52 x 10-4 M
In 6.00 ml