We can use the ideal gas law to determine the molar mass of the gas. The ideal gas law is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the absolute temperature.
The standard temperature and pressure conditions (STP) are commonly defined as a temperature of 0°C (273 K) and a pressure of 1 atm. We are given that the gas occupies a volume of 12.0 L at these conditions, so we know that V = 12.0 L at STP.
We also know that the mass of the gas is 23.6 g. We can convert the mass of the gas to moles by dividing by the molar mass (M) of the gas. The number of moles (n) is equal to the mass of the gas divided by the molar mass.
n = m/M
we have m = 23.6 g
By substituting into the ideal gas law and solving for M, we can find the molar mass of the gas.
PV = nRT
(1atm) * (12.0 L) = (n) * (R) * (273 K)
n = PV / RT
R is ideal gas constant which is specific to the units of the PV and T and we can assume its value for calculating the n.
We can now use n value to find the molar mass
M = m/n
M = 23.6 g / n (n is calculated from the ideal gas law)
It is important to remember that ideal gas laws assume that gases behave as ideal gases and are not accurate at high pressures or low temperatures. Also, it assumes that the gas is perfectly pure and does not take into account any interactions between the gas molecules.