To determine the total pressure of the gas mixture, we need to assume that the gases are ideal so we use the equation PV = nRT where P is the pressure, V is the volume, n is the number of moles, T is the temperature of the system and R is the universal gas constant. We assume that the temperature of the system would be at 25 degrees Celsius. The pressure is calculated as follows:
PV = nRT
P = nRT / V
P = (0.02 + 0.01) (0.08205) (25 + 273.15) / 2.5
P = 0.2936 atm
Therefore, the pressure in the gas system would be 0.2936 atm