Re: Science question about explosions
The amount of gas produced by the 9mm bullet charge I described will occupy about a pint at STP, but obviously those conditions of volume, temperature and pressure are not under our control. It's just the standard we use.
In general, use the equation of state of an ideal gas,
PV = nkT
where
P = Pressure
V = Volume
n = the number of atoms or molecules
T = Temperature in degrees Kelvin
k = Boltzmann's constant, a number selected to make the answer come out in whatever units you are using.
The Kelvin temperature scale is the same as the Celsius, except the zero point is at Absolute Zero, not at the freezing point of water.