Chemistry - Spectroscopic techniques, colorimetry - activity 4
Spectroscopic techniques, colorimetry - activity 4
A 3.05 g sample of steel was analysed to determine its manganese content.
The steel sample was dissolved in sulfuric acid and the resultant solution
treated with an oxidant to convert all the manganese to permanganate ions
MnO4(aq) in a total volume of 100 mL.
The absorbance of this solution was measured in a colorimeter under the
same conditions previously used to measure the absorbances of 100 mL
solutions of known MnO4(aq) concentration.
The following experimental data were recorded:
(a) Write a balanced half-equation showing the conversion of Mn ions to
MnO4(aq) ions and state what this tells you about the amount of manganese
in the sample and the amount of MnO4(aq) produced in the oxidation.
(b) Use the supplied data to construct a calibration curve of absorbance
v. c(MnO4) and determine the concentration of MnO4 produced in the steel
(c) Calculate the percentage, by mass, of manganese in the steel sample.
(d) State a possible source of error in this analysis.
Answer - part a and b
Answer - part c and d
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