In order to calculate this, we should use the ideal gas law, PV=NRT.
Next, let’s write down the values that we know and what we are solving for.
P = pressure = 1.59 atm
V= volume = ???
N= moles of gas = 20.6gCH4 * (1molCH4/16.04gCH4) = 1.28molCH4
R=constant (you have to look this up) = 0.08206
T = 27C + 273K = 300K
Now, plug these values in and use algebra to solve!
(1.59 atm)(V) = (1.28molCH4)(0.08206Latm/molK)(300K)
Isolate V:
[(1.28molCH4)(0.08206Latm/molK)(300K)]/1.59atn
V = 19.8 L