Purifying Potassium Nitrate (KNO3)

Song: Battle Without Honor or Humanity by Tomoyasu Hotei



   Procedures for purifying chemicals are being invented and re-invented all the time. Purification depends very much on the chemicals that are considered the “contamination”, and their properties compare to the chemical you are trying to purify. The mixture that you are trying to purify will dictate how easy the purification process will be. There are no– "one fit all solutions", and indeed, some chemicals are so hard to purify that the finished purified product will fetch amazing prices.

   Recrystallization is a physical method targeting the purification of compounds. This procedure involves dissolving a compound in a hot solvent to form the saturated solution followed by cooling down the solution. The dissolved compound would crystallize from the solution due to the difference in solubility at high and low temperatures. This method is especially effective for potassium nitrate (KNO3) since its solubility in 158g of water is 247g at 100 degrees C, and only 13.3g at 0 degrees C.

 

Supplies:

Stump remover that contains Saltpeter (KNO3)

Water (H2O)

Paint stick or spoon

Pot or pan

Jar

Funnel (optional)

Hot plate

Safety glasses

Step 1 Measurements

   First, weigh out 247g of stump remover and set it to the side. Now measure 175ml of H2O (which is about 158g in weight). You can multiply these numbers if you would like.

Comments

[minerug]

Can this work for getting potassium nitrate out of garden fertilizer?

[YoungPyro19]

This procedure is just for purifying KNO3 from stump remover.

I think this is what you’re looking for==> http://www.youtube.com/watch?v=g4FpKqG93rY

The process is similar. Study the video and improvise.

[BytePilot]

Something ain't right... Water is pretty close to 1g/ml so 100g of water should be 100ml not 175ml...

[YoungPyro19]

Okay you just about right. I measured and weighed the H2O again and it turned out that 175ml weighs 158g.

[BytePilot]

Even that's a bit of a worry. At 20 degrees C (approx room temperature) the density of water is 998.2 kg/m^3 that means it should be 0.998g/ml. That would put 175ml of water at 174.6g If your scales are showing 158g they may not be as accurate as needed for this task. But hey, if you always use the same scales and the same measurements, you should get the same resuts.

[YoungPyro19]

I don’t know much about water density, but I suppose you’re right. Also, when I measured the H2O for a second time I used a more accurate scale.

[masterochicken]

I've been needing this!

[YoungPyro19]

Ok, well I hope it will be very helpful to you.

[masterochicken]

Smoke bomb time!

[YoungPyro19]

Ohh YEAH! =)

[jtobako]

How would 175ml H2O be less than 175g?

[YoungPyro19]

Weight is not the same as volume. Volume is how much three-dimensional space a substance (solid, liquid, gas, or plasma) occupies. Weight is a measure of the heaviness of an object.

[jtobako]

Right. And water has a density of 1g/ml. Strange how the French chose it that way : )

[D6U4]

or you could go on ebay and just buy kno3

[YoungPyro19]

Yes, but shipping cost can kill. This process is not hard at all.