Gunpowder's burning rate increases with pressure, so it will burst containers but just burns in the open. Ignition of the powder packed behind a bullet must generate enough pressure to force it from the muzzle at high speed, but not enough to rupture the gun barrel.
The gas constant occurs in the ideal gas law, as follows: where P is the absolute pressure (SI unit pascals), V is the volume of gas (SI unit cubic metres), n is the amount of gas (SI unit moles), m is the mass (SI unit kilograms) contained in V, and T is the thermodynamic temperature (SI unit kelvins).
The numerical value of the gas constant, R) in the ideal gas law (equation 3-8) depends on the units in which pressure and volume are measured -assuming that only the absolute, or Kelvin, temperature scale is used. If pressure is in atmospheres and volume is in liters, then R = 0.082054 liter atm K-1 mole-1.