How to identify KOH and NaOH

[ngian]

Hello everyone,

I read a very interesting question from a soaper in a Greek fb group, where she has a bag with a base and she doesn't know if it is KOH or NaOH as the info-sticker outside the bag is not present .

So in my google search for the answer to this problem, I found a very interesting video showing an easy experiment on how to determine which type of base someone has if there is no info upon this ingredient. It is known as a flame test.

[ame]https://www.youtube.com/watch?v=ZsvsptBQUVQ[/ame]

I didn't find any similar threads here in SMF, so I hope this will help people with similar issues...

 

[ngian]

But I have a question to make...

Are these Na+ and K+ ion metals solutions made of NaOH & water and KOH & water respectively?

 

[galaxyMLP]

These solutions are likely made up with potassium chloride and sodium chloride. They are safer to use in solution than say NaOH or KOH.

One potential problem I see with this is that a candle flame might not be hot enough to do this. Bunsen burners use methane gas for a clean and very hot burn that allows for the flame test to happen. I remember trying it in 9th grade with a candle at home and it didn't work. It also may have been that the existing yellow color of the flame interfered too much.

You can actually do this with the straight salt instead of a solution and it works just as well if not better. You would only need 1 lye bead on a wire to see what you have in that case instead of having to make a solution.

 

[topofmurrayhill]

One potential problem I see with this is that a candle flame might not be hot enough to do this. Bunsen burners use methane gas for a clean and very hot burn that allows for the flame test to happen.

A gas range should be reasonably equivalent to the Bunsen burner. A propane burner is another possibility. Or one of those butane cigar lighters with the hot blue flame.

 

[ngian]

I did the test myself but it was a bit difficult to identify the type of lye only by the color of the flame...

I was using a copper wire that was dipped in a NaOH and KOH distilled water solution.

 

[LBussy]

Copper wire will add it's own color to the flame at some temps - a stainless steel wire would be best. A SS skewer will do in a pinch.

 

[ngian]

Copper wire will add it's own color to the flame at some temps - a stainless steel wire would be best. A SS skewer will do in a pinch.

Yes that is correct, as I saw it happening after 4-5 sec of burning it alone when it created its own flame...