Chemical Reaction between Potassium Permanganate and Citric Acid

Picture of Chemical Reaction between Potassium Permanganate and Citric Acid
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Hello friends, I am back with my 9th instructable. This time I am playing with chemicals. We are going to do a reaction with Potassium Permanganate and Citric Acid. The reaction will be hydrolysis reaction because salt (Potassium Permanganate) and Water are getting reacted together. The citric acid is working as a catalyst.

I got the idea when I've seen a video of potassium permanganate is added to water and immediately the water gets purple. I thought what if I add citric acid to it? And Voila! this purple water gets converted from purple to red then orange then yellow then fully transparent yellow. Enough talk, lets do it!

Video of reaction(Time Lapse):

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Step 2: Adding and Heating Citric Acid Crystals

Picture of Adding and Heating Citric Acid Crystals
Add 100 ml of water in a beaker. Add citric acid. If you are using crystals then heat it a little bit for around 10 second. This will make the crystals disolve better. Using liquid will do the reaction a little bit faster so use liquid if you can. Use plastic spoon to mix it.

Step 3: Adding Potassium Permanganate

Picture of Adding Potassium Permanganate

Add about 2 grams of Potassium Permanganate to the beaker and stir it periodically. Minute by minute it color gets lighter and brighter. At the end, you can even see through!

Chemical reaction as shown by Kymyst :

6H+ 5C6H8O7 + 2MnO4-  ------> 5C5H6O5 + 5CO2 + 8H2O + 2Mn2+

Here is the video if you've not seen in the intro step.

I hope you like this 'ible. Any question or idea, or anything, you can freely ask me in the comment section.

Sorry for my bad english.

kymyst6 months ago

The initial reaction is oxidation of the citric acid to acetonedicarboxylic acid , carbon dioxide and water. The acetonedicarboxylic acid is further oxidised to acetone and carbon dioxide. Other reactions which can occur ( depending on the conditions, including temperature and concentration of the reactants ) are the formation of oxalic acid and formic acid. The reaction mechanisms are rather complicated. If you want to know more, search for scientific articles referring to permanganate oxidation of citric acid.

azharz (author)  kymyst6 months ago

Can you please describe it in formula method?

kymyst azharz6 months ago

Crikey, you are really testing my
memory ! I haven't needed to calculate balanced redox equations for
many years. If you continue to study chemistry, you will find that
organic chemists rarely bother to use balanced equations because they
are more interested in the movements of the bonding electrons in
reactions. Nevertheless, I think the following equation is applicable
to this reaction :

Oxidation of citric acid to
acetonedicarboxylic acid

+ 5 C6H8O7
+ 2 MnO4 -
5 C
+ 5 CO2
+ 8 H
+ 2 Mn

kymyst kymyst6 months ago

I am having a problem formatting this reply; it will not accept changing the font size, the equation should be on one line, and the following paragraph was cut off : There are several other possible reactions which may or may not occur simultaneously, depending on the exact reaction conditions. They mainly involve splitting off carbon dioxide and water from the organic compounds being oxidised, as in the example above.

azharz (author)  kymyst6 months ago

You are my Guru kymyst, I really appreciated your chemical equation and I am going to add it in this instructable. Actually when I am trying to solve the equation, mine one was like this one you've shown above. I am not a perfectionist in chemistry but I love chemistry, I am in 10th class, and I don't no much about these reactions. Thanks Kymyst.

kymyst azharz6 months ago

You are welcome, I'm glad to help you learn chemistry. But you will probably not study reactions like this one in high school, this is university-level organic chemistry. By the way, you have left off the negative charge on the permanganate ions in the equation, they should be MnO4 (-) ( single negative charge )

kymyst6 months ago

This reaction is a little more complex than "hydrolysis". The citric acid does not act as a catalyst, because catalysts by definition are not consumed in the overall reaction. In fact, the citric acid is being oxidised by the permanganate and is consumed in the reaction, with the end products including acetonedicarboxylic acid, acetone, formic acid, carbon dioxide and manganese (II) ions.

azharz (author)  kymyst6 months ago

Oh thanks, actually I am finding the information on the internet of the reaction but getting nothing. Can you please also describe the chemical reaction?


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