In a 600 mL beaker, create an aqueous solution of 0.01 M KMnO4 (be sure to expla
ID: 837438 • Letter: I
Question
In a 600 mL beaker, create an aqueous solution of 0.01 M KMnO4 (be sure to explain how this is done and show your calculations in the materials and methods section).Right click on the beaker and select rename.Rename it 0.01 M KMnO4. To one of the beakers, add 100 mL of 10 M H2SO3 and 100 mL of 10 M NaHSO3.Note the pH.Label this beaker acidified. To another beaker, add 200 mL of 10 M NaHSO3 (use two of the flasks). Label this beaker control. Note the pH. To the third beaker, add 100 mL of 10 M NaOH and 100 mL of 10 M NaHSO3.Note the pH. Label this beaker basified. Add 100 mL of 0.01 M KMnO4 to each of the three beakers. Also include the chemical equations for the reactions that took place (there are three major reactions, one for each of the different media). Explain why there was solid precipitate in all of the beakers.Describe some limitations of this procedure, some future research that might be conducted, and some applications for your results.
Explanation / Answer
The oxidation state of manganese in potassium permanganate is +7, which is reduced by `NaHSO3` to different degrees to form various oxidation states, and corresponding colour changes are observed.
In neutral solution (control), orange colour is observed due to the formation of `MnO2` .
In the basified solution, green colour due to `Mn^(+7)` is observed.
In the acidic solution, a faint pink colur is obtainable due to the formation of `Mn^(2+)` ions.
The balanced chemical reactions are as follows:
Neutral:
3NaHSO3 + 2KMnO4 +NaOH --> K2SO4 + 2Na2SO4 + 2MnO2(s) + 2H2O
Basic:
NaHSO3 + 3 NaOH + 2 KMnO4 --> Na2SO4 + Na2MnO4 + K2MnO4 + 2H2O
Acidic:
4NaHSO3 + H2SO3 + 2KMnO4 --> K2SO4 + 2Na2SO4 + 2MnSO4 +3H2O
The solid precpitates in all the beakers are due to the manganese salts which are produced in all three reactions, which are insoluble (MnO2, MnSO4 etc)
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