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Tuesday, June 9, 2015

Oxidation Reduction Reaction Problems, 2

Category: Chemical Engineering Math

"Published in Vacaville, California, USA"

Calculate the percentage of MnO2 in a 500 mg sample which after the addition of 80.00 mL of 0.1056 M FeSO4 solution required 8.50 mL of 0.0867 M K2Cr2O7?

Solution:

The given word problem is about oxidation reduction reaction or redox in short. A given sample consists of the mixture of impurities and MnO2. FeSO4 solution is used to titrate MnO2 sample and K2Cr2O7 is used for back up titration. Sulfuric acid is added as a catalyst as follows


For back up titration, K2Cr2O7 solution is used to titrate excess FeSO4 solution as follows



The amount of FeSO4 used to titrate MnO2 is 


 
 

Hence, the weight of MnO2 in a sample is 
 
 

Therefore, the weight percent of MnO2 in a sample is