Sciencemadness Discussion Board

Dehydration of Calcium Peroxide Octahydrate

APO - 4-5-2013 at 13:55

I had an idea for dehydrating it by leaching out the water with Isopropanol and then adding Sodium Chloride to make the Calcium Superoxide layer imiscible with the layer of salt water formed and then sucking up the Calcium Superoxide layer with a syringe and then boiling off the Isopropanol leaving the anhydrous Calcium Superoxide. I had another idea to dehydrate it by adding Acetone to make it less polar and then boiling that off. If I can dehydrate it by heating alone, someone give me a specific temperature. I have no idea if I can use a simple desiccating chamber.

Prometheus23 - 4-5-2013 at 14:36

You cannot mix calcium peroxide with water. If you'd like to know why you can google it. It's literally the THIRD sentence on the results page when you search for calcium peroxide...

Also, calcium peroxide and calcium superoxide are not the same thing. But hey, that's probably somewhere on that page of google results too.

[Edited on 5/4/2013 by Prometheus23]

APO - 4-5-2013 at 15:05

My bad, I meant Peroxide not Superoxide. I'm just having trouble finding a simple way to dehydrate Calcium Peroxide Octahydrate to obtain the anhydrous form. I was thinking maybe that ANHYDROUS Isopropanol would dissolve Calcium Peroxide (since I heard that Strontium Peroxide dissolves in alcohol) and that in solution it would split up into Calcium Peroxide and water, and that by adding Sodium Chloride, it would separate into two layers (since Isopropanol is imiscible with salt water), so that I would have one of salt water and one of anhydrous Isopropanol/anhydrous Calcium Peroxide. Also I had another idea were I would add it to Acetone/Isopropanol so that once the Isopropanol had dissolved it, the polarity of the Acetone would have a higher affinity for the water than the Calcium Peroxide would so that I could then boil off the solution for the pure product. I heard it can be dehydrated by heating, but no specific temperature was stated. Anyway you guys know of that 100% works please give details. Even if a desiccating chamber will work with a certain desiccant.

Adas - 5-5-2013 at 03:06

Even though you would manage to dehydrate it successfully, the main impurity would be CaO. I believe that this could be removed by very carefully adjusting pH to make the CaO dissolve in the slightly acidic environment, leaving the CaO2 behind. Just an idea, though this could also lead to decomposition. The reaction of CaO2 with water is not very fast, but is visible. Probably ice-cold water would do.

unionised - 5-5-2013 at 03:20

Ignoring the fact that it won't do what you want to do for the minute; do you really want to mix a fuel with this strong oxidiser?

kristofvagyok - 5-5-2013 at 07:20

It is usually dried in a vacuum desiccator under oxygen atmosphere for a few days, or at 80-100 Celsius. Avoid even traces of CO2 at elevated temperatures, since it will cause decomposition the peroxide.

The ideas with azeotropic distillation is simply insane. Do not even try to mix those two and start to boil that mixture. You will suffer really soon from really bad looking injuries.
And for the insane idea with the acetone... Do you heard about acetone peroxide? Imagine that there is only a little acid left in your acetone or at the surface of the Ca-peroxide hydrate. You start to boil it and when it reaches the point when it's almost dry you will hear a loud bang. These stuffs at even trace quantities could be dangerous. Don't be stupid.

APO - 5-5-2013 at 21:09

Damn, totally forgot about TATP. But thanks for the procedure kristofvagyok .

unionised - 6-5-2013 at 00:27

Don't worry too much about forgetting stuff. We all do it.
For example, kristofvagyok is about to kick himself when I point out that calcium peroxide is nearly as strong a base as calcium hydroxide so if I " Imagine that there is only a little acid left in your acetone or at the surface of the Ca-peroxide hydrate. " then I imagine that it will be neutralised with the production of a small amount of hydrogen peroxide.
My guess is that, at least up until the point where oxidation sets in and the mixture explodes, the actual reaction with acetone would be something like this
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1...


The real issue is that, unless you are planning to make explosives and rocket fuels, you should be very careful about mixing oxidants and fuels.

woelen - 6-5-2013 at 01:25

APO, I have a serious suggestion for you: try to teach yourself some basic chemistry! I see multiple posts from you, most of them about energetic compounds, on how to obtain them. This is not the way to go. You look like a k3wl in this way and people more and more respond to you as if you were a kewl, who just wants a quick bang and wants to impress his friends with some energetic stuff. This is not cool at all, actually it looks childish.

Basic concepts you need to teach yourself:
- Atoms, elements, molecules
- Symbolic representation of chemical compounds
- Reaction equations and how to balance them
- Acids and bases
- Redox reactions
- Analytical methods (qualitative, but also quantitative)
Try to do experiments which demonstrate the things you teach yourself.

If you teach yourself some chemistry, then you understand things and then you even might be able to design your own methods of synthesis and separation. Also, try to make easier to prepare and less risky compounds first. While doing so, you obtain a lot of theoretical and practical experience and it is very rewarding to show the result of your work.

Some suggestions:
- Make CuCl2.2H2O from copper metal, dilute hydrochloric acid and hydrogen peroxide, or use electrolysis to dissolve a copper anode. All chemicals are easy to get, you can use plain stranded electrical copper wire as a source of copper. At the same time, this synthesis already gives quite a few challenges and from a theoretical point of view it demonstrates a few very important basic concepts.
- Try to purify chemicals from hardware stores, e.g. make higher concentration ammonia from 5% household ammonia, distill 10% muriatic acid to make pure 20% hydrochloric acid.

Remember this: You first need to be able to walk before you can think of running.

[Edited on 6-5-13 by woelen]

I'm not as dumb as I seem.

APO - 8-5-2013 at 14:59

Quote: Originally posted by woelen  

Basic concepts you need to teach yourself:
- Atoms, elements, molecules
- Symbolic representation of chemical compounds
- Reaction equations and how to balance them
- Acids and bases
- Redox reactions
- Analytical methods (qualitative, but also quantitative)
Try to do experiments which demonstrate the things you teach yourself.
[Edited on 6-5-13 by woelen]


I'm familiar with all these.

Bot0nist - 8-5-2013 at 18:06

Obviously...

Finnnicus - 8-5-2013 at 18:12

Do it apo. Learn again.

APO - 8-5-2013 at 22:43

Finnnicus, what?

Finnnicus - 8-5-2013 at 22:53

Basic concepts. Start from the start, even if its boring.