Question

The rate of reaction of nitrogen monoxide with oxygen was measured at 25 degree C starting with various initial concentrations of NO and O2. 2 NO(g) + O2(g) --> 2 NO2(g) The data collected is summarized in the following table: Trail n Initial concentration mol / L Initial reaction rate mol/l.s 1 0.020 0.010 0.028 2 0.020 0.020 0.057 3 0.040 0.020 0.227 a. Use the method of initial rates to find the reaction orders with respect to NO and O2. Hint: for which trial s was the concentration of NO changed while [O2] remained constant?

Answer 1

Consider trial 1 and 2 when concentration of NO is constant but concentration of O2 becomes double Rate becomes double,So

Rate $\propto$ [O2]

Now consider trial 2 and 3 when concentration of O2 is constant but concentration of NO becomes double Rate becomes almost 4 times.

Rate $\propto$[NO]²

^Therefore Rate =k [NO]²[O2]

order of reaction = 2 +1 =3