A chemistry graduate student is studying the rate of this reaction: 2NH3(g) N2(g) + 3H2(g) He fills a reaction vessel with NHz and measures its concentration as the reaction proceeds: time (seconds) [NHz] ale 0 0.400 M Ar 10. 0.0751 M 20. 0.0414 M 30. 0.0286 M 40. 0.0218 M Use this data to answer the following questions. Write the rate law for this reaction. rate = k 0.0 Calculate the value of the rate constant k. k = 0 Round your answer to 2 significant digits. Also be sure your answer has the correct unit symbol