The gas phase decomposition of dimethyl ether follows first order kinetics.
CH3 - O - CH3(g) → CH4(g) + H2(g) + CO(g)
The reaction is carried out in a constant volume container at 500°C and has a half life of 14.5 min. Initially only dimethyl ether is present at a pressure of 0.40 atm. What is the total pressure of the system after 12 min? Assume ideal gas behaviour.