At 400 K oxalic acid decomposes according to the reaction:

H2C2O4(g)?CO2(g)+HCOOH(g)

In three separate experiments, the intial pressure of oxalic acid and final total pressure after 20,000 s is measured.

Experiment

1

2

3

P H2C2O4 at t = 0

65.8

92.1

111

PTotal at t = 20,000 s

107

150

181

Find the rate law of the reaction.