The role of KNO3 in Sgar/KNO3 rocket fuels

[vincent4e]

I have been confused with this for a very long time and still havent found an answer to it...does the KNO3 make it easier for the sugar to burn ?

 

I am not very sure...

So can the pros here help me out?Thanks..

 

Another thing is that whether can I find another easily obtainable chemical in place of the KNO3? This is because KNO3 is very hard to get in my country(Singapore)..

 

Yes there are alot of pharmacies here, but none of them sell chemicals at all...

[fredrik]

A natural use for KNO3 is in preparing salted ham as it preserves an attractive colour of the ham. Here at least, you can buy it in supermarkets along with food additives and baking stuff. It's often called salpeter.

 

It's a oxidation agent needed for the sugar or carbon to burn.

 

Not to discourage your interest in chemistry, "smoke and fire" is always fun but be careful when playing with those things. People do get hurt all the time, in particular when then don't know what they are doing. Even if you know what you are doing things can go wrong, a mistake, or microsparks can come from all over the place and to work with explosive and flammable stuff without know what you are doing is something you may regret. So think twice, and never do anything blindly.

 

Your question indicate that you don't know exactly what you are about to do, and this is reason to raise a warning for your own health.

 

/Fredrik

[vincent4e]

So if lets say I make this equation of the reaction between KNO3 and Glucose, C6H12O6 :

 

12KNO3 + C6H12O6 = 6 CO2 + 6 H2O + 12 KNO2 (Am I right, please correct me)?

[fredrik]

So if lets say I make this equation of the reaction between KNO3 and Glucose, C6H12O6 :

 

12KNO3 + C6H12O6 = 6 CO2 + 6 H2O + 12 KNO2 (Am I right, please correct me)?

 

The general idea that the carbon source is ideally combused into carbon dioxide and water is right, however in general, real life combustion reactions are rarely have that simple and controlled stochiometry. You'll get mixed end products depending on how the combustion is carried out and relations of reactants. Various carbonbased residues, nitrogen, potassiumcarbonate, and possibly some mixed nitrious oxides too but probably not that much KNO2.

 

For black powder(Carbon,sulphur and KNO3) there are several suggested approximating balancing formulas but real life combustions give a range of end products, also depending on conditions. It can't be determined in a general setting. See for example http://www.du.edu/~jcalvert/phys/bang.htm#Blac for comments. But reality isn't that simple. Combustions aren't very controlled.

 

/Fredrik

[YT2095]

it`s an Oxidiser.

[jdurg]

I've actually NEVER heard of potassium nitrATE being used as a preservative or curing agent. Potassium nitrITE, yes, but not nitrate.

[SkepticLance]

2KNO3 + heat = 2 KNO2 + O2

 

When the nitrate is hot, it releases pure oxygen that aids in the burning of the sugar.

[fattyghost]

So if lets say I make this equation of the reaction between KNO3 and Glucose, C6H12O6 :

 

12KNO3 + C6H12O6 = 6 CO2 + 6 H2O + 12 KNO2 (Am I right, please correct me)?

 

In most case , yes . But most sugar are not pure

[John Cuthber]

Most sugar is probably more nearly pure than the KNO3.

 

A lot of the KNO3 will also decompose to NOx (which will oxidise more sugar, making CO2 nitrogen and water) and K2O which will react with CO2 to give K2CO3.

There's a good chance of getting CO as well.

Flames etc. are messy- they don't react cleanly.

[ercdndrs]

In basic terms, heated KNO3 releases oxygen so that the sugar can be oxidised (burned) inside the rocket as opposed to using oxygen present in the atmosphere (which doesn't make for a very good rocket, does it? ). It also will contain more oxygen than the same volume of air.

 

As for alternatives for Saltpeter or KNO3, try cold packs. Some cold packs contain sodium nitrate which has very similar properties to KNO3. However, most cold packs have either ammonium nitrate (that while being an oxidiser like KNO3 and NaNO3, won't work for a rocket) or urea which is useless as part of rocket fuel.

 

Also for rocket fuel (slower burn) don't grind the fuel and nitrate too much or your rocket will accelerate apart instead of upwards

 

Hope this helped

Edited April 5, 2010 by ercdndrs
grammar