Chemical Reaction of RCandy

[TranslucentDragon]

So I've been making R-Candy using the dissolving in water and boiling out the water to form crystals. I was wondering what the actual chemical reactions were when making and using the fuel. I'm looking for: 1) is it true that when "boiling out the crystals" it isn't a chemical reaction that occurs, but just the sugar molecules coating the saltpeter; 2) if so, what is the chemical reaction that occurs when you actually burn the fuel (what is converted to what){don't include any additives, just the normal 60/40-saltpeter/sugar mix}; and 3) how does red iron oxide lower the activation point of the mix, or if it doesn't lower the activation point, why does Red Iron Oxide make R-Candy burn faster; 4) does Sulfur do the same thing as Red Iron Oxide?

[TommyP]

Sorry, I can only answer one of your questions, and that is if iron oxide and sulfur do the same thing? - and I can say with certainty no. I have tried many different things over the years and from adding sulfur I found it slowed down the reaction and made much more smoke and residue. Could be just the amounts, but I believe iron oxide works as a catalyst. Hopefully others can answer your questions for you.

[brimstoned]

I think carbon is the only part of the sucrose molecule that is oxidized by KNO₃. Note that in C₁₂H₂₂O₁₁ the hydrogen and oxygen are balanced to form water, the vapor phase of which contributes to thrust.

Iron oxide is also used as a catalyst in whistle mix, though copper oxychloride seems to be superior; I wonder if the copper compound would give good results in a sugar-based propellant?

Edited July 11, 2013 by brimstoned

[Mumbles]

It's going to depend on the ratios, but the combustion reaction in RCandy will primarily make water, carbon dioxide, nitrogen gas, and some final potassium product. The final potassium product is probably potassium carbonate. There are probably dozens of other minor products formed too. BP forms over 30 measurable products from combustion.

 

I have no idea how the iron oxide actually works. Many transition metals are very good at catalytically forming reactive oxygen species, leading to further decomposition and faster reaction rates. Basically the chemical reaction just takes a different pathway that requires less energy input.

 

I really have no idea if anything chemically happens while boiling down the reaction mixture. Something chemically happens when doing something similar with just sugar when making candy, so perhaps there is a little something going on, but it probably doesn't really effect anything other than making a very intimate mixture.

[Bfitzy]

In making some candy the sucrose molecule splits, forming a molecule of fructose and a molecule of glucose/dextrose. This mixture is called invert sugar.

[Respirator]

I agree with Mumbles that the final potassium product tends to be potassium carbonate. This explains the characteristic white smoke from sugar/nitrate rockets, which makes coloring the flame annoying even with a chlorine donor. (The smoke mostly drowns the flame.)

Nothing chemically happens when boiling the fuel mixture, Is just that usually, only the sugar melts, but in the recrystallization method, both the nitrate and the sugar dissolve, yielding more intimately combined results.

 

I would expect corn syrup to be largely invert sugar (high glucose/fructose content) and is widely used in KNSU or polyol based fuels but I have never heard of the sucrose splitting while bieng cooked into fuel.

[Respirator]

As to the Iron oxide question, I might mix up a batch of fuel and chemically analyse the burnt residue for certain iron compounds - might give some information.