[alex00]

Hi,
who know the production of "Potassium tetraoxalate dihydrate" "KH3(C2O4)2 .2H2O
Thanks

[Hunter2]

Dissolve 0.5 mol potassium carbonate in0.5 l water. Add slowly during stirring 2 mol oxalic acid. Get the water evaporated over some days.

[alex00]

Thanks alot.it saved me alot of time and effort.
I think the equation is like this:
4H2C2O4+K2CO3+3H2O=2KH3(C2O4)*2H2O+CO2
I calculate the amont of parts like this:
H2C2O4=652 gr
K2CO3=250 gr
H2O=1800 gr
when I mixed it I saw the bubbles and when it finished I stop to add oxalic acid. do I must continue to add oxalic acid or not?

[Hunter2]

I dont know how you calculate youir masses. I said 0.5 mol potassium carbonate what means 69 g and according your equation 90 g oxalic acid,if it is anhydrous.
You have to add the calculated masses. If you stop after gassing disappears, then its to less acid.

[alex00]

this is my calculation:
Molar mass K2CO3= 138
Molar mass H2C2O4= 90

then if I want using 250 gr K2CO3 then I must using 652 gr H2C2O4
and acording to your text I using 1800 gr water.

so I will try again and waiting to form crystals and then inform you
Thanks

[Hunter2]

Ok.  Sounds correct. Water could be also less. More then 97 ml.

[alex00]

Hi
I mixed it today. but the oxalic acid does not solve in this amount of water.I think they must solve in the water completely, so I increase the amount of water to dissolve all oxalic acid. it was about 20 Kg instead 1.8 Kg.
is it important?
should I waiting for evaporate all the water?
thanks

[Hunter2]

Yes the solubilty is poor. 17 g/l at 20 ° C. For 250 g you need 14,7 l.

Yes all the water has to be evaporate. After some days you will get cristallisation.

[alex00]

Hi
I am waiting for water evaporation now.
this salt contain oxalic acid. Do you know any salt that containing HF acid ?

[Hunter2]

Yes ammonium biflouride  NH₄HF₂ = NH₄F x HF.
The same with Sodium or potassium

[alex00]

Hi
I saw the formed crystals.
Thanks
I have some question about it
1. is possible to form any other compositions in this process like potassium bioxalate?
2. is the PH controllable? or the crystals PH is constant?
3. I need the large grain. and I think the water must evaporate very slowly. is there any catalyst for this purpose?is there any problem with the heating the mixture?
Thanks alot for your helps

[Hunter2]

If you mix different amounts of the chemicals other ratios can be obtained. Of course the crystallization process has to go over some days to get large crystals. To store it on a warm place or in sunlight it will help.

[alex00]

Is this method using for industrial production?I think it will be very costly. it need very water and months to evaporate it.

[Arkcon]

Why do you need very large crystals for an industrial process?  Sigma will sell you the powder, presumably for  a reasonable price.  But if there is an application that requires large crystals for any purpose, then temperature controlled slow growth is necessary.  And that manufacturing cost is reflected in the sale price.

[alex00]

I don't the ability for importing this salt, so I must to producing for myself now. the Hunter2 help me alot and I thanks him/her very. it is very useful for me.Thanksssss