Calculate the half life of the first-order reaction:C2H4O(g)⟶CH4(g)+CO(g)The initial pressure of C2H4O (g) is 80 mm and the total pressure at the end of 20 min is 120 mm.

C2H4O(g) ⟶ CH4(g)+CO(g) t = 0                        P0                        0               0 t = t                         P0-x                  x                x  Total pressure Pt=P0−x+x+x=P0+x P0=80mmP0+x=120mm∴x=120−80=40mmk=2.20320log⁡P0P0−x=2.320log⁡8080−40k=2.3×0.320⇒t1/2=0.69k=0.69×200.69=20min