Homework Question

Question

a) Determine the Rate Law for the reaction of NO with O₂ using the experimental data below. Remember that experimental values are never perfect. Use your best judgement to determine the order of each reactant.   

Rate Law: __________________________

(Show your work)

 

b) If the initial concentration of NO was tripled while the initial concentration of O₂ was quadrupled, what effect would this have on the initial rate?

 

Answer 1

(a). Comparing experiments 1 and 2, we see that [NO] is constant and [O₂] doubles. We see that the rate doubles also. This tells us that the reaction is FIRST order in O₂

Next, we compare experiments 5 to 2 and we see that [O₂] is constant and [NO] doubles. Here we see that the rate increases by 4 times (4x), going from 0.014 to 0.057 mol/L-s. This tells us the reaction is SECOND order in NO.

The rate law is:

Rate = k[NO]²[O₂]

(b) If [NO] is tripled and [O₂] is quadrupled, the initial rate would change as follows:

Rate = k (3)²(4)¹ = 36k so the rate would increase by 36 times.