Calculating Density of Gas from Combusted Solid w/ Known Wt, Pres, Vol

AI Thread Summary
To calculate the density of gas from a combusted solid propellant, the ideal gas law may not be applicable due to the high pressure of approximately 29,000 psi. The user has a known mass of the propellant and the chamber's volume and temperature, leading to questions about the validity of using the equation ρ = MP/RT. It is suggested that the behavior of gases under such extreme conditions may require a different model, as real gas behavior deviates significantly from ideal gas assumptions. The discussion emphasizes the need for accurate density calculations for applications related to firearms and reloading, particularly concerning recoil and compensation. Understanding the limitations of the ideal gas law at high pressures is crucial for accurate modeling.
tjhj
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Hello,
Thank you all for the help here.

Here we go, I have a known solid weight start of the propellent. I know the PSI of a known volume chamber(After combustion) and Temperature, can I find density?

So example
Bullseye powder has a load of 0.336954332 grams (5.2 grains)
The volume of the barrel is 0.39591921 in3
The pressure at this point is approx. 29,000 psi
Burn temperature = 2100k

I am thinking because the known mass of the air in the chamber, plus the mass of the powder can be used for the total mass in the density of the ideal gas equation. \rho = MP/RT

Is this assumption correct? Will there be a substantial difference if I did not use the ideal gas law? I don't have the slightest clue what model would be appropriate to figure this as a "real" gas. Any suggestions?

This might make more sense in what it relates to. This is related to firearms and reloading. I am trying to figure out the density of the gas in the barrel just before it leave the chamber. This is part of a larger problem having to do with recoil and compensation, but this simple part I just can not seem to make connect.
 
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tjhj said:
Hello,
Thank you all for the help here.

Here we go, I have a known solid weight start of the propellent. I know the PSI of a known volume chamber(After combustion) and Temperature, can I find density?

So example
Bullseye powder has a load of 0.336954332 grams (5.2 grains)
The volume of the barrel is 0.39591921 in3
The pressure at this point is approx. 29,000 psi
Burn temperature = 2100k

I am thinking because the known mass of the air in the chamber, plus the mass of the powder can be used for the total mass in the density of the ideal gas equation. \rho = MP/RT

Is this assumption correct? Will there be a substantial difference if I did not use the ideal gas law? I don't have the slightest clue what model would be appropriate to figure this as a "real" gas. Any suggestions?

This might make more sense in what it relates to. This is related to firearms and reloading. I am trying to figure out the density of the gas in the barrel just before it leave the chamber. This is part of a larger problem having to do with recoil and compensation, but this simple part I just can not seem to make connect.
Using the ideal gas law is not valid at 2000 bars.
 

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