At a certain temperature the rate of this reaction is second order in NH3 with a rate constant of 2.45 M^-1. s^-1:
2NH3(g) → N2(g) + 3H2(g)
Suppose a vessel contains NH3 at a concentration of 0.590 M. calculate the concentration of NH3 in the vessel 9.20 seconds later. You may assume no other reaction is important.
Round your answer to 2 significant digits.