Sciencemadness Discussion Board

Making KOH with Potassium Carbonate

Runningbear - 9-3-2010 at 03:15

Hi Guys,

I want to make a small amount of KOH from potassium carbonate and calcium hydroxide. Can anyone tell me the correct percentage of each I should be boiling?

Thanks in advance,

Runningbear

Jor - 9-3-2010 at 03:28

1 mole of potassium carbonate per 1 mole of calcium hydroxide. Take a slight excess of potassium carbonate because it is hygroscopic (so contains some water) and you will have carbonate in your hydroxide anways (by reaction with CO2 from the air) and calcium interferes in much more reactions than carbonate.

Runningbear - 11-3-2010 at 04:33

Thanks for the feedback Jor.

Potassium bicarbonate is 100.12 grams per mole

Calcium hydroxide 74.093 grams per mole

Allowing for the hydroscopic nature of potassium carbonate, I'm guessing about a 10% excess should be used.


So the correct ratios would be approximately 110 grams potassium carbonate to 75 gram calcium hydroxide?

Does that sound about right?