vmelkon
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Making permanganate and wikipedia
For the first time, I decided to make some permanganate.
According to wikipedia and other sources, you just heat some hydroxide (example : KOH) with MnO2 with a certain careful temperature control. Drop it
in water. The solution will be GREEN because of the manganate ion. Then it turns PURPLE. Then it turns RED.
From my understanding, manganate oxidized because of O2 in the air or water. Is that correct?
What is the equation exactly? Something like...
MnO4(2-) + O2 -> MnO4(-) + MnO2
Ok, next question. Why does it turn RED?
I did the experiment. The stuff is in water now. It looks green just like FeSO4. Interesting stuff. I'm going to observe it the next few days.
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vmelkon
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No one knows why it would turn red?
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Poppy
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Wherein has wikipedia to do with that?
Descriptively, it turns red because atomic scale rearragements occurs in the electronic energy leves of the permanganate molecules, bringing its
absorption band aside resulting in the observable chromatic change fo the spectrum
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unionised
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CO2 from the air.
KMnO4 +H2CO3 --> K2MnO4 + K2CO3 +MnO2
But I will leave balancing it to the interested reader.
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vmelkon
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I'm going to assume that your english isn't very good and you meant to say "where in wikipedia does it say that".
It says in the history section for KMnO4
| Quote: | | In 1659, Johann Rudolf Glauber fused a mixture of the mineral pyrolusite and potassium carbonate to obtain a material that, when dissolved in water,
gave a green solution (potassium manganate) which slowly shifted to violet and then finally red. |
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