An atmospheric scientist interested in how NO is converted into NO2 in urban atmospheres carries out two experiments to measure the rate of this reaction. The data are tabulated below.

Question

A: [NO]0 = 9.63 × 10-3 M, [O2]0 = 4.1 × 10-4 M
t(s) 0 3.0 6.0 9.0 12.0
[O2](10-4 M) 4.1 2.05 1.02 0.51 0.25

B: [NO]0 = 4.1 × 10-4 M, [O2]0 = 9.75 × 10-3 M
t (102 s) 0 1.00 2.00 3.00 4.00
[NO](10-4 M) 4.1 2.05 1.43 1.02 0.82

The rate constant was calculated to be R=k[O2][NO2]^2 .

I need to find the value of k. In order to find the value of k, I need to find R for a specific set. How do I find R?

Answer 1

To find R, you will need to use the rate law equation R=k[O2][NO2]^2. This equation states that the rate of the reaction is proportional to the concentration of O2 and the square of the concentration of NO2.

To find the value of R for a specific set of data, you will need to first determine the concentration of NO2 at each time point in the experiment. This can be done by subtracting the initial concentration of NO from the concentration of NO at each time point to determine the concentration of NO2.

Once you have determined the concentration of NO2 at each time point, you can use the rate law equation to calculate the rate of the reaction at each time point by plugging in the values for [O2] and [NO2] at that time point.

Finally, you can average the values of R calculated at each time point to find the overall rate of the reaction. Once you have this value, you can plug it into the rate law equation along with the concentrations of O2 and NO2 at one of the time points to solve for the value of k.