Standardization of KMnO4 Titration Data PDF

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M9 Check-in Activity 1 PART A. 1] Without adding sulfuric acid (H2SO4), will the reaction take place? Justify your answer. •

Without sulfuric acid, the reaction will not occur because permanganate ion (MnO4-) is reduced to manganous ion (Mn2+), which is colorless in solution when used in titration. A drop excess of the MnO4- ion tints the solution a pale pink color. The reaction is complete when the solution retains its color. Without the sulfuric acid, it is incapable of acting as an oxidizing agent and cannot be used to determine the presence of reducing substances in solution, resulting in an incomplete reaction.

2] What indicator is used in the experiment? Explain. •

Potassium permanganate is used as an indicator because its color is considered as as selfindicator and visible to the naked eye. Dark purple KMnO4 solutions when used as a titrant, usually the solution turns permanent pink when the endpoint is reached and the KMnO4 is in excess. Hence, KMnO4 is an indicator.

3] Why is it necessary to heat the acidified oxalic acid solution to 80oC before titration? •

The reaction will occur at a higher temperature, which is why oxalic acid is heated prior to titration with KMnO4 solution. If not heated, the light pink titrated solution quickly turns brown and the reaction takes longer, and excessive heat results in oxalic acid decomposition as CO2.

Preparation and Standardization of KMnO4 solution Experimental data Complete the table below. Trial 1

Trial 2

Trial 3

0.2001 g

0.2065 g

0.2050 g

Final reading

29.86 mL

30.66 mL

30.52 mL

Initial reading

0.00 mL

0.00 mL

0.00 mL

Total vol. of KMnO4 used

29.86 mL

30.66 mL

30.52 mL

Computed Molarity of KMnO4 solution

0.02000 M

0.02010 M

0.02005 M

Weight of sodium oxalate (Na2C2O4, MM= 134 g/mol) Titration data

Mean Molarity

Computed Normality of KMnO4 Mean Normality of KMnO4 solution

0.02005

0.1000 N

0.1005 N 0.1003

0.1003 N...