6 replies to this topic

[spectrum]

I'm not sure if this has ever appeared here before but can anyone provide information on the quantity of gas generated by one gramme of gunpowder at ambient temperature and pressure?

 

 

[digger]

Volume?

[spectrum]

Yes, volume in litres is all that's required.

[cooperman435]

I'm sure we had a few threads in it but on my phone I'm struggling to find them :-/

[digger]

I will look it up in the morning, it is in the RSC book

Edited by digger, 30 July 2016 - 12:16 AM.

[samboradford]

Shidlovskiy P70 Principles of Pyrotechnics lists a value of 280 cm³ g^-1 @ V₀ for "Smoke Powder" [ KNO₃ 75%, Wood Charcoal 15%, Sulfur 10% ] , gaseous combustion products given as CO CO₂ H₂O N₂ So that's quite good as it includes the water vapour produced.

 

why he calls it "smoke powder" I have no idea.

 

V₀ is 0⁰C and 760mmHg

 

If you want to know what volume the gas occupies at a different temperature (V_t) you use the following formula ( it's at the bottom of page 67 ) :

 

V_t = 280 * (1+0.00366 * T)

 

so  25 degrees it's :

280 * (1+0.00366 * 25) = 305.62 cm³

 

so you could equally find out the volume at the reaction temperature by substituting the combustion temperature of BP

 

Exactly how accurate it is I don't know, someone else might have a different answer.

[Crazy Cat]

Some further information that may assist?

The Chemistry of Fireworks. Page 57.VOLUME OF EVOLVED GASES. https://www.exploder..._2009_196s..pdf

ProPEP (Propellant Performance Evaluation Program), a MSDOS program to calculate Isp. http://www.arocketry.net/propep.html

Example: For every gram of BP you burn, you obtain 0.0182 moles of gas and 0.0026 moles of condensibles. The combustion temperature of BP is 1739K, so the hot gas peak volume is (1739/273)*(0.182/0.014) = 8.3 times the cold gas volume, which for 1 gram of BP is 2600 cm^3 or 157 cubic inches at 1 atm pressure. As the gas expands and cools down the volume shrinks until it reaches the ambient temperature. Of the more volatile gases, you get 0.0158 moles including water and 0.0140 excluding water. The volume of a mole of gas at 273K is 22.4 liters, so 1 gram of BP generates at least 313 cm3 or 19 cubic inches of cold gas per gram of BP @ 1 atm. pressure. See attachment for details calculated by propep. http://www.rocketryf...hp/t-23568.html

One gram of blackpowder gives you 718 calories of heat, 270 cubic centimeters of gas, and about half of a gram of residue. http://www.chuckhawk...der_pyrodex.htm

The firefighting gunpowder makes only 8.57 litres of gas per kilo of gunpowder which causes it to have an explosive power of 563 x 103 L kJ kg-2 which compares with 839 x 103 L kJ kg-2 for normal gunpowder. I suspect that the lack of sulphur in the fire control gunpowder will slow down the reaction which will reduce further the explosive effect of this special gunpowder. https://markforeman....011/09/04/1284/