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Oxidation-Reduction 37 Pre-lab Titrations I Questions Determination of Oxalate B

ID: 506028 • Letter: O

Question

Oxidation-Reduction 37 Pre-lab Titrations I Questions Determination of Oxalate Before beginning this experiment in the laboratory, you should be able to answer the following questions. 1. IfoA58s g of sodium oxalate, Narczo., requires 33.67 mL ofa KMno, solution to reach the end point, what is the molarity of the KMno. solution? 2. Titration of an oxalate sample gave the following percentages 15.53% 15.55% and 15.56%. Calculate the average and the standard deviation. 3 Why does the solution docolorize upon standing aner the equivalence point has been reached? 4. Why is the KMaOe solution filtered, and why should it not be stored in a 5. What volume of 0.100 MKMno. would be required to titrate 0.23 gof K2(cu (co.ol.2Ho? Calculate te percentczo Copyright o20ls Pearson Education, Ise.

Explanation / Answer

1)

the balanced equation is :

2KMnO4 + 5Na2C2O4 + 8H2SO4 ----------> K2SO4+5Na2SO4+2MnSO4+10CO2+8H2O

moles of Na2C2O4 = 0.4586 / 134 = 3.42 x 10^-3 mol

from the balanced equation :

2 mol KMnO4 ----------------> 5 mol Na2C2O4

?? KMnO4   ------------> 3.42 x 10^-3 mol Na2C2O4

moles of KMnO4 = 3.42 x 10^-3 x 2 / 5 = 1.37 x 10^-3

moles = molarity x volume

1.37 x 10^-3 = M x 33.67

Molarity of KMnO4 = 0.0406 M