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.
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] 4.1/2.05/1.02/0.51/0.25
*[O2] is in(10-4 M)
B: [NO]0 = 4.1 × 10-4 M, [O2]0 = 9.75 × 10-3 M
t(s) 0/1.00/2.00/3.00/4.00
[NO] 4.1/2.05/1.43/1.02/0.82
*[NO] is in(10-4 M)
I figured out the rate law:
Rate=k[O2][NO]2
But I can't find the rate constant! Please help!
"Calculate the rate constant. (in M-2 s-1)"
Did anyone end up getting this. if you plug in the numbers above you still need the retain rate to find k. How do you do that??!!
Use any one of the points of experimental data. Plug in [O2], [NO2] and the rate, solve for k.
What number is the rate ?
bless your soul F
To calculate the rate constant (k) for the reaction, we can use the rate equation and the experimental data provided.
Let's start with experiment A and use the initial rate method:
1. Choose any two sets of data points from experiment A with different times but the same [NO] and [O2] values. For example, let's select the first and fourth data points:
t1 = 0 s, [NO]1 = 9.63 × 10^-3 M, [O2]1 = 4.1 × 10^-4 M
t2 = 12 s, [NO]2 = 9.63 × 10^-3 M, [O2]2 = 0.25 × 10^-4 M
2. Calculate the rate of reaction for each set of data points using the rate equation:
Rate1 = k([O2]1)([NO]1)^2
Rate2 = k([O2]2)([NO]2)^2
3. Divide the second rate by the first rate to cancel out the rate constant:
Rate2/Rate1 = (k([O2]2)([NO]2)^2) / (k([O2]1)([NO]1)^2)
Rate2/Rate1 = (([O2]2)([NO]2)^2) / (([O2]1)([NO]1)^2)
4. Substitute the given values into the equation:
Rate2/Rate1 = ((0.25 × 10^-4) × (9.63 × 10^-3)^2) / ((4.1 × 10^-4) × (9.63 × 10^-3)^2)
5. Simplify the equation:
Rate2/Rate1 = (0.25 × 10^-4) / (4.1 × 10^-4)
Rate2/Rate1 = 0.061
6. Rearrange the equation to solve for the rate constant (k):
Rate2/Rate1 = k2 / k1
k2 / k1 = 0.061
7. Since k1 is the rate constant for the initial reaction (t = 0), we can assume k1 = k for simplicity. Therefore, the equation becomes:
k2 / k = 0.061
Now, repeat the steps for experiment B using the same process:
t1 = 0 s, [NO]1 = 4.1 × 10^-4 M, [O2]1 = 9.75 × 10^-3 M
t2 = 4 s, [NO]2 = 8.2 × 10^-4 M, [O2]2 = 0.82 × 10^-4 M
Rate2/Rate1 = ((0.82 × 10^-4) × (8.2 × 10^-3)^2) / ((9.75 × 10^-3) × (4.1 × 10^-4)^2)
Rate2/Rate1 = 16
k2 / k = 16
Now, we have two equations:
k2 / k = 0.061
k2 / k = 16
Since both equations are equal to k2 / k, they must be equal to each other:
0.061 = 16
k2 / k = 0.061
Solving for k, we find:
k = k2 / 0.061
k = (16) / 0.061
Calculating this gives the rate constant k in units of M^-2 s^-1.
rate constant is 0.23 M-2 s-1
(just got it right on Sappling)