Hi there,
I was one day a little off track, I filled up some Falcons with reaction chemicals and moved to my working place. One I labeled with Natriumhydroxxide
(pattys - is this called like that? - small white pellets...?)
And one Tube I forgot to write down what it is - I think it is Kaliumhydroxyde (It really looks the same). Can I find out if it is KOH for shure - a
pH mesurement couldn't tell me whether it is NaOH or KOH....
Some Idea - I know this is stupid question but otherwise I'd have to throw it away - I don't like wasting chemicals...
Thanks
CGwoelen - 1-10-2012 at 05:57
KOH dissolves in ethanol better than NaOH. Take some known NaOH (e.g. drain cleaner) and dissolve this in ethanol. Then take some of your unknown and
compare.
If you have NaClO4, NH4ClO4 or HClO4, then the difference is even more easy to determine. Prepare a moderately concentrated solution of your unknown
(e.g. 10% by weight) and mix this with a 10% solution of any of the three chemicals mentioned above. On mixing, the KOH will give a very fine white
precipitate of KClO4. NaOH will not give any precipitate.
Yet another option: Take a small piece of magnesia or chalk and heat this in a blue roaring flame, until any strong orange color of the flame is
nearly gone. Then allow the piece to cool down and soak with the solution. The NaOH-solution will lead to a strong yellow/orange color of the flame,
the KOH-solution only weakly adds color to the flame (somewhat purplish).SM2 - 1-10-2012 at 06:06
i don't know where this thread went, so in case no one said it yet, kalium=potassium natrium is sodium, at least in serbo croatian, and I suspect many
parts of slavic Europe.
and oh careful w/ the NaOH, look for signs of efferecence. tablets are good, but eventually a bottle of NaOh will turn into carbonate. It's no
lie.,,,,,,,when it looks flakey like that, it's natrium carbonate,.
[Edited on 1-10-2012 by Fennel Ass Ih Tone]tetrahedron - 1-10-2012 at 06:49
Although the sodium salt is soluble in water, those of potassium and ammonium are insoluble
chemguy5000 - 1-10-2012 at 11:37
Thank you guys for the fast reply!
Kalium = Potassium ! My fault! thanks for the hing Fennel....
I'll try those methods woelen mentioned (the one with the flame).
We had Organic Chemistry only one semester and that has been a while.
I'll work on my basics!
gckristofvagyok - 1-10-2012 at 13:47
Flame test! The most important and most easier to get know which alkali is it.UnintentionalChaos - 1-10-2012 at 13:49
If you have a little sodium perchlorate, a solution will yield a gelatinous ppt with KOH, but not NaOH.phlogiston - 1-10-2012 at 14:24
The proposed methods (flame test, perchlorate) are practical and cheap, but just to add to the growing list of increasingly elaborate and creative
means to distinguish between the two:
1. The one with the higher conductivity should be KOH (If the concentration is the same).
2. A good geiger-muller tube: the one with the highest radioactivity will be the KOH
3. Convert into chloride and add hexachloroplatinic acid. The potassium salt will precipitate, while the sodium salt is soluble.AJKOER - 7-10-2012 at 13:57
So carefully neutralize your unknown aqueous base with an aqueous solution of Oxalic acid. If a near boiling solution as a significant amount of
undissolved precipitate, suspect NaOH.
