A reaction is first order and it takes 324 minutes for the reaction to be 50.0% complete. How long will it take for the reaction to be 85.0% complete at the same temperature?
2. N2O5 decomposes to N2O4 and O2 and the reaction is first order in N2O5 with a specific rate constant of 6.22 x 10^ -4 sec^-1 at 45 C. What will be the initial rate of formation of oxygen if the concentration of N2O5 is 0.100 M?
1. k = 0.693/t1/2
solve for k and substitute into the following:
ln(No/N) = kt
I would use No = 100 (just an arbitrary number), then N would be 15 left if it was 85% complete. Solve for t.
Thank you so much. That makes more sense. I had in 85, not 15.
It will take 550.8min for the reaction to be 85% complete at the same temperature
To solve this problem, we need to use first-order reaction kinetics.
1. For the first part of the question, we are given that the reaction is first order and it takes 324 minutes for the reaction to be 50.0% complete. This means that we can use the equation for first-order reactions: ln[A] = -kt + ln[A]0, where [A] is the concentration of the reactant at a given time, k is the rate constant, t is the time, and [A]0 is the initial concentration of the reactant.
We can rearrange this equation to solve for t: t = (ln[A] - ln[A]0) / -k
Since the reaction is 50.0% complete, we know that [A] = 0.5[A]0. We can substitute this into the equation and solve for t:
t = (ln[0.5[A]0] - ln[A]0) / -k
Now, to find the time it will take for the reaction to be 85.0% complete, we can use the same equation. We know that [A] = 0.85[A]0, so we can substitute this into the equation and solve for t:
t = (ln[0.85[A]0] - ln[A]0) / -k
2. For the second part of the question, we are given the specific rate constant (k) for the reaction and the initial concentration of N2O5. We can use the rate equation for a first-order reaction: rate = k[A], where rate is the rate of formation of the product and [A] is the concentration of the reactant.
In this case, the product is O2. So, the initial rate of formation of oxygen can be calculated by substituting the values into the rate equation:
rate = k[N2O5]
Given that the concentration of N2O5 is 0.100 M, we can substitute this value into the equation to find the initial rate of formation of oxygen:
rate = (6.22 x 10^ -4 sec^-1)(0.100 M)
By multiplying the values, we can find the initial rate of formation of oxygen in units of M/sec.