Flash mix question

[ssdd]

So over the past few months I have worked with many different flash powder mixes. I recently found one while browsing the internet that sparked my intrest and I just have a few questions.

The mix was as follows:
3g Potassium Permanganate, 1g Aluminum (fine mesh)*, 1.5g Sulfur
*I do most of my work in my school where I am limited to what the school stocks in their chemical room, so I substituted with Mg 500 mesh.

The instructions for this powder said that upon the addition of water it should react. Needless to say it didn't. :confused: (It did react when a burner was put to the mix.)I have 2 questions. The first being why didn't it react when water was added (all the other flash mixes I used from this source worked well.); was it the Mg?

And I was left with a green pebble like residue from this reaction after it reacted with the burner what could this be? My inital thoughts are Permangante Oxide but perhaps you guys would know.

Would Zinc dust work for this?

Thanks

[Rbick]

I think it could be the Mg instead of the Al that is causing your problem. Both Mg and Al react with water, but in different ways. In both cases, the reaction is most violent when coming into contact with steam, and slows as the temperature of the water is lessens. At room temperature, both metals have very, VERY low reactivity with water unless extremley pure. The reaction of Mg with steam is as follows
Mg+H2O --------> MgO+H2, or Magnesium Oxide and Hydrogen gas.
The reaction with Al is the same except the products are Aluminum Oxide and Hydrogen gas. Aluminum is known for its reaction with a strong base, such as sodium hydroxide, which when mixed, reacts strongly with water in a exothermic reaction (production of a lot of heat). In your case the base is the sulfur, which is used to lower the PH in gardens and what not. When the Al is added to the water, it creates AlO and also reacts with the sulfur in an exothermic reaction, igniting your flash. When enough heat energy is produced the Potassium Permaganate then releases its oxygen to the remaining sulfur and Al, resulting in a BANG :eek:

So most likley, it is your Mg instead of Al that is messing you up. When you do get Al (off ebay for 10 USD), make sure it is very pure and make sure your other chemicals are pure as well. If there are any flaws in my idea, please point them out to me. Thanks and good luck.

[ssdd]

As I sit here and think about it, while they are both not very reactive at room temperature, Mg has a higher ignition temp than Al dose. My thinking is that this is probably the main problem. I'll have to see if I can dig up some Al dust and try it, or actually I may try Zn first. Think that would work?

I also think that the green residue left behind was a Permanganate Oxide. Since Permangante acts as a catalyst to the decomp of H2O2 I added some of this green stuff to a 3% hydrogen peroxide to see if it generated oxygen gas. It did witch makes me feel it was Permanganate Oxide. Any thoughts? Hope noone minds me asking this as a newbie and i appreciate all/any help.

[Rbick]

Sorry I didn't make my first post more clear. The mixture works because of Al being so reactive with a base and water, therefore leaving out other metals. Unlike Al and Mg, Zinc does not react with water, so it wouldn't work. But the main point is that Al is the way to go. Aluminum is reactive with these compounds whereas Mg is not, hence you not having any luck with the Mg.

[spaceninja]

Potassium permanganate mixes will not ignite when water is added.Try using silver nitrate as your oxidiser which ignites upon contact with water in certain flash comps.Mg/AgNO3 mixed 1:1 will ignite after about a second and will burn very quickly and is very relaible.The green pebble like stuff could possibly be manganse heptoxide as the sulphur burns to produce sulphur dioxide which then dissolves in the water to form weak sulphuric acid and then reacts with whatever is left of the permangante to form manganese heptoxide which is green.

[ssdd]

I am going to try that flash mix when I get back into school Tuesday... sounds like it would be a neat one to add to my list of things I have tried.

In regards to the Manganese Heptoxide; Couldn't this only have formed (in the manner described) if I had used Al in the reaction and successfully set it off with water?
After researching on it a bit, it seems as if this could have been it. But it seems as if it is a highly reactive material and should have been consumed or decomposed in the reaction. It says it decomposes explosively at 55*C and the dish I set of the flash in was well over that after the powder had reacted.
Im gona look around and see if theres a good way to test and see if this is the heptoxide.

[m88k]

Potassium permanganate won't ignite when combined with water normally, but it will react violently with glycerin or ethelyne glycol (this can take up to a minute, more likely twenty seconds, but DON'T assume its a dud)

It also (theoretically) will respond to water in the presence of sugar.

[spaceninja]

Yes finely powdered permanganate mixed with finely powdered sugar will ignite when water is added.Sorry i never mentioned that.

I don't think that Al is needed to produce the heptoxide as the reactants needed to produce it are just potassium permanganate and sulfuric acid.

Apparently the heptoxide reacts with most fuels it comes in contact with I have seen items such as shaving foam,paper and wood being dropped on it and they turn into small fireballs,another possible test is to take a small amount <1g or something and heat it strongly on an watch glass or something similar and see what happens.

[ssdd]

My thinking has me wondering if it is MnO2. I think that the Heptoxide did form during the reaction but was broken down by the extreme heat left behind from this.
USE
It may help to point out that there was a similar volume of this green material left over at the end as there was reactants in the beginning.
PARAGRAPH
The reason I think this is because the Heptoxide breaks down at near room tempature and somewhere (Ill go hunting for them...) I have pics that show this product of the reaction glowing red hot. But when the Heptoxide breaks down it does produce MnO2.
BREAKS
I'll keep hunting google...