Consider the following reaction between nitrogen dioxide and carbon monoxide: NO
ID: 764016 • Letter: C
Question
Consider the following reaction between nitrogen dioxide and carbon monoxide: NO2(g) + CO(g) -----> NO(g) + CO2(g) The initial rate of the reaction was measured at several different concentrations of the reactants with the results shown below. The result on the left is the molar concentration of NO2, the result in the middle is the molar concentration of CO and the result on the right is the initial rate in units of M/s: 0.10, 0.10, 0.0021 0.20, 0.10, 0.0082 0.20, 0.20, 0.0083 0.40, 0.10, 0.033 Determine the rate law and the rate constant (K) for the reaction. Show all your work.Explanation / Answer
The data is
a) taking first and second readings where concentration of CO is constant the rate of reaction will depend upon only on the concentration of NO2
Rate = K [NO2]a
Where a = order of reaction with respect to NO2
At [NO2] = 0.1 , rate = 0.0021
at [NO2 = 0.2 , rate = 0.0082
So on doubling the cocnetration of NO2, the rate of reaction becomes four times
So the order with respect to NO2 = 2
b) now we will consider, second and thrid reading where concentration of NO2 is constant the rate of reaction will depend upon only on the concentration of CO
Rate = K [CO]b
The rate of reaction remains the same on doubling the concentration of CO
So the Order of reaction with respect to CO = zero
Rate law will be
Rate = K [NO2]^2
Rate = 0.0021 = K [0.1]2 =
K = rate constant = 0.21 M-1 second-1
[NO2] [CO] Rate 0.1 0.1 0.0021 0.2 0.1 0.0082 0.2 0.2 0.0083 0.4 0.1 0.033