Sciencemadness Discussion Board

potassium tartrate

bilcksneatff - 19-11-2007 at 16:16

According to wikipedia, potassium tartrate will react with water to form tartaric acid and potassium hydroxide. Is this equation correct?

K2C4H4O6 + 2H2O --> H2C4H4O6 + 2KOH

Does this even work? If it does, can you make potassium tartrate from cream of tartar (potassium bitartrate)?

not_important - 19-11-2007 at 16:26

Wiki :
Quote:
To a small extent, potassium tartrate reacts with water to form potassium hydroxide and tartaric acid.


This is similar to the way sodium acetate gives some Na+ OH-, and its solutions are slightly alkaline. If you evaporate the solution you'll get the original salt back.

To make mono-potassium tartrate from cream of tartar, you buy cream of tartar - it's the acid salt - the mono-potassium salt or potassium hydrogen tartrate.

http://physchem.ox.ac.uk/MSDS/PO/potassium_bitartrate.html

tartarates rock

chloric1 - 19-11-2007 at 16:54

Dude there are so many uses for tartarates. One if you like crystal growing, bring some water to rapid boil and add a premeasured amount of cream of tartar so some dissolves then add baking soda at a rate that prevents the foam and liquid from leaving the reaction vessel. Allow the fully neutralized solution to cool crystals of Rochelle's salt.

Tartaric acid is found at wine and beer brewing suppliers. This can be used to prepare ammonium bitartrate which can change potassium salts into there ammonium counterparts.
Tartaric acid can be made from calcium tartrate and dilute sulfuric acid.


Thats not to mention silvering mirrors, Tollen's reagent, and as a chelating agent for electroplating etc.

bilcksneatff - 19-11-2007 at 17:02

Quote:
Originally posted by not_important

To make mono-potassium tartrate from cream of tartar, you buy cream of tartar - it's the acid salt - the mono-potassium salt or potassium hydrogen tartrate.

http://physchem.ox.ac.uk/MSDS/PO/potassium_bitartrate.html


Cream of tartar is potassium BI-tartrate which is KC4H5O6, I was talking about potassium tartrate K2C4H4O6

chloric1, the crystal growing idea sounds really cool, I'm gonna have to try that one!

How would you silver mirrors with it?

not_important - 19-11-2007 at 17:31

If you want to get di-potassium salt, you'll have to add KOH or K2CO3, or potassium acetate and do a slow distillation to remove acetic acid..

You might be able to get the di-K salt from the mono-K salt if either the di-K salt or the free acid were much less soluble that the mono-K salt; however the mono-K salt is the least soluble of the three.

bilcksneatff - 20-11-2007 at 04:20

Quote:
Originally posted by not_important
If you want to get di-potassium salt, you'll have to add KOH or K2CO3, or potassium acetate and do a slow distillation to remove acetic acid..

You might be able to get the di-K salt from the mono-K salt if either the di-K salt or the free acid were much less soluble that the mono-K salt; however the mono-K salt is the least soluble of the three.


KC4H5O6 + KOH --> K2C4H4O6 + H2O
2KC4H5O6 + K2CO3 --> 2K2C4H4O6 + H2O + CO2
KC4H5O6 + CH3COOK --> K2C4H4O6 + CH3COOH

Would these be correct?

YT2095 - 20-11-2007 at 04:52

I`ll give you a tip in case you don`t already know, although Rochelle salt grows lovely large crystals, it can be a little tricky if your not used to it.

you Will need to take a small amount of the liquid and dry it completely 1`st, then pick your best small crystal out of that to use later as a Seed (a Nucleation site).

now the strange part if that the Liquid is like thick honey, very viscous indeed, unlike say saturated copper sulphate or table salt.

into this "Syrup" will go your seed crystal, and if you have the saturation just right, it won`t dissolve again but will start growing, this can be very much trial and error too, keep the temp as stable as possible and allow the liquid to evaporate slowly.

the tricky part is that just left alone in a room, it will take in moisture from the air and dilute itself again!
I`ve found that a bit of thin cloth over the top and keep the whole beaker on top of my PSU is what works best for me, YMMV.

something interesting you can do when you`ve made a large-enough-to-handle crystal is put a small metal plate either side of the crystal with a wire off each, and hook them up to an Oscilloscope, you`ll see a Spike every time you tap the crystal :)

Piezo-electric effect.