To find the amount of gas in moles, we can use the Ideal Gas Law, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.
Rearranging the equation to solve for n, we get:
n = PV / RT
Plugging in the given values, we get:
n = (2 atm) * (20 L) / (8.31 J/mol*K * 400 K)
Converting atm to Pa:
n = (2 * 101325 Pa) * (20 L) / (8.31 J/mol*K * 400 K)
Converting liters to cubic meters:
n = (2 * 101325 Pa) * (0.02 m^3) / (8.31 J/mol*K * 400 K)
Solving the equation:
n = 0.077 mol
So there are approximately 0.077 moles of gas in the 20-liter container at a pressure of 2 atm and a temperature of 400 K.