KMnO4 Flash-Powder

[xoo1246]

I have made KMnO4 in my dreams a couple of times. This far I have made sulfurless. What I was thinking of was the ratios. What is the formula for the reaction between the Al and the KMnO4?
I did a try on my paper and it looks like this:
3KMnO4 + 2 Al --> Al2O3 + 3KO2 + 3MnO
But when I calculate the ratios in weight the percentages looks very odd in comparation with the ratios generally accepted.
Question: Is my formula totaly messed up or is it correct but most of the Al in ordinary flash after-burns in air?
Thanks in advance.
Edit: Another thing, has anyone tried Ti flakes/powder in flash or other compositions, I was thinking of getting some.

<small>[ June 08, 2002, 11:24 AM: Message edited by: xoo1246 ]</small>

[BrAiNFeVeR]

I use the 3:2:1 (KMnO4:Al:S) method and it works fine for me, but most recipe's are heavily over-fueled.
I think it depends on the brightness of the flash you want.

For the good old noise makers, I'd use stochiometric + 5 % Al, because some fuel is allways oxidised by the surrounding air ...

KMnO4 = 39.1 + 54.94 + 72 = 166.04
Al = 26.98

26.98/166.04 = 0.162 gram Al per gram of KMnO4

+ 5% schould make 1.7 gram Al + 10 gram KMnO4.
As soon as I have my cam (sometime next week I hope) I'll try it out ...

[vulture]

Ok, finding the decomposition of KMnO4 reaction can cause something worse than a nitroheadache... <img border="0" title="" alt="[Wink]" src="wink.gif" />

But hey, here it is!

18 KMnO4 + 26 Al -&gt; 6 Mn3O4 + 9 K2O + 13 Al2O3

158.03 * 18 = 2844.54

26.98 * 26 = 701.48

Brainfever, you made a little mistake there, to calculate the ratio you divide the weight of one compound through the weight of the total amount of all compounds:

(2844.5 / (2844.5 + 701.48)) * 100% = 80.22% KMnO4 and 19.78% Al.

For magnesium the equation is as follows:

12 KMnO4 + 26 Mg -&gt; 4 Mn3O4 + 6 K2O + 26 MgO

Have fun calculating the reaction enthalpy!

[xoo1246]

Your calculations looks ok, but does K2O exist?, I though potassium oxide was KO2. And there you sure only Mn3O4 is formed, there are:
Manganese(II)oxide
Manganese (III) oxide
and your Manganese(II,III) oxide.
But hey, I'm not educated at all when it comes to chemistry, I'm working on it.

[vulture]

I'm absolutely sure Mn3O4 is formed, MnO2 decomposes into it. The KMnO4 equation you see here is a multistep reaction which I brought together in one reaction.
And sure does K2O exist, K = +1, O = -2, go figure.
KO2 is potassium superoxide.

[xoo1246]

Good.
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">And sure does K2O exist, K = +1, O = -2, go figure.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Well, that's what I thought at first too, but my damn chemistry book didn't even mention it when talking about oxides of potassium.

[Omogen]

You posted the same damn thing in two seperate topics! And you've only got 2 posts!

:msd:

And no live chat. Been discussed a million times already and is explained in the FAQ if you had BOTHERED TO READ IT!

<small>[ June 10, 2002, 11:03 AM: Message edited by: nbk2000 ]</small>

[rikkitikkitavi]

vulture, i read your reaction and one idea strikes me.

add more Mg!

K2O + Mg = 2K + MgO

Mn3O4 + 8K = 3Mn + K2O

flash turnes into thermite ...

But if one did this with NaMnO4 instead, the yellow colour of sodium would increase the flash?

/rickard
/rickard

<small>[ June 10, 2002, 12:51 PM: Message edited by: rikkitikkitavi ]</small>

[vulture]

Hmm, although it seems theoretically possible because of the high temperature the reaction requires is present, I doubt it would work.
Don't forget that K is a much stronger reductant than Mg.

If it all possible, I think this will only happen in a sealed container, that is a firmly closed metal object which can take loads of pressure and which won't melt.

[rikkitikkitavi]

no, actually Mg, Al and Ca are the strongest reductants at high temperatures.
K has been produced through Al-reduction. K can even be produced through reduction with carbon, but K(CO)n messes things up a bit :)
The high volatility of the alkalimetalls favours the redoxreaction too.

anyway, I think you are right. Would probably not work since the
flashpowder just "blows" the mixture apart.

/rickard

[Rat Bastard]

I just tried the acetone method for my KMnO4 flash, and it turned my flash powder from silver to goldish-brown colour.

What did I do wrong?

[mr.evil]

I guess that there is formed some Mno2(wich is dark brown-black and turned the Al into brown)
if it's burn well there's nothing to complain about <img border="0" title="" alt="[Wink]" src="wink.gif" />

[vulture]

That's okay. It happens because the permanganate crystallizes inside Al and S grains. The Al and S give the goldish color while the permanganate creates the brownish color in combination with that. It just indicates it's perfectly mixed.

MnO2 formation is impossible, because permanganate can't oxidize acetone.

<small>[ June 14, 2002, 09:22 AM: Message edited by: vulture ]</small>

[Rat Bastard]

mine was sulphurless..

<small>[ June 16, 2002, 02:55 AM: Message edited by: Rat Bastard ]</small>

[Rat Bastard]

Anyways It burned quite nicely, so I guess I shouldn't complain.

I saw a pic where someone made some KMnO4 Flash-Powder withe the acetone method, and it was silver.

<small>[ June 14, 2002, 07:35 PM: Message edited by: Rat Bastard ]</small>

[mr.evil]

does anyone has a little video or something so i can see how fast the KMnO4 flash mix burns? ( i will make it myself when i have KMnO4 again)

if you make a little train of 20centimeters or something, how fast will it be gone? :confused:

(maybe a little kewl question, but i like to know)

[vulture]

A train of 20cm will be gone before you can even blink your eyes, possibly with a small bang.

<small>[ June 15, 2002, 01:41 PM: Message edited by: vulture ]</small>

[mr.evil]

wow! that's really fast :D
i can't wait 'till you've been in Brussels to get (my) chems Vulture, offcourse i will pay you <img border="0" title="" alt="[Wink]" src="wink.gif" />

(sorry for off topic, last post about this)

[xoo1246]

I don't have a video camera but I have a couple of pictures showing flash going off. Check my ftp(look below)

[zaibatsu]

Cut your sig down rat bastard

[mr.evil]

I've just buyed a Digital Cam!! :)
WOW, that stuff is bright, how fine was your Al?

[xoo1246]

That flash contained Al particles &lt; 80um

[chem]

This is miles ok,ok kilometers of what your now talking about but K20 is usally refered to as potassium superoxide in a chem book I own.

[vulture]

Potassium superoxide = potassium hyperoxide (official IUPAC name)= KO2. This is created when K2O (potassium oxide) is heated in O2 and is a very powerful oxidant.

The other oxides of potassium are:
K2O = potassium oxide, the normal oxide, looking at the oxidation states
K2O2 = potassium peroxide, powerful oxidizer (H2O2 and O2 formation with water)
K2O3 = potassium trioxide, which I don't have much info about
KO3 = potassium ozonide, formed by the reaction between ozone and K2O or KOH.

Old chemistry books usually use the super and hyper oxide notations in the wrong place. The info I present here is from a 2001 chemistry encyclopedia.

[spaceninja]

I have always made my KMnO4 flash without sulphur as I make my flash out of KMnO4 and Mg powder.This is a pretty powerful mix and I'm not sure if I want to add sulphur incase it makes the mix too sensitve.I was just wondering if anybody has any pictures of this mix burning at all?

[inFinie]

Delayed starting of ignition by dropping glycerine is an interesting method to me.

And

K2O + Mg = 2K + MgO
Mn3O4 + 8K = 3Mn + K2O

Seems impossible in normal(physical) conditions to me since electronegativity of K is 0.82 and Mg is 1.31 on Pauling's scale, Mg will not reduce K2O to K. The other equation seems possible but not in solid state maybe in liquid state, oxygenless medium.

Mn3O4 is afaik MnO.Mn2O3 ?