In a decomposition reaction NO --> products, a plot of the on [ NO] vs time yiel
ID: 569964 • Letter: I
Question
In a decomposition reaction NO --> products, a plot of the on [NO] vs time yields a straight line with a slope of -0.0363/s. If the initial concentration of [NO] is 4.0 M, what is the concentration after 155 seconds? What is the half-life of the reaction? In a decomposition reaction NO --> products, a plot of the on [NO] vs time yields a straight line with a slope of -0.0363/s. If the initial concentration of [NO] is 4.0 M, what is the concentration after 155 seconds? What is the half-life of the reaction? If the initial concentration of [NO] is 4.0 M, what is the concentration after 155 seconds? What is the half-life of the reaction?Explanation / Answer
1)
ln[N2O5] vs t is straight line
So, it is 1st order reaction
for 1st order reaction,
slope = -k
so,
k = 3.63*10^-2 s-1
[N2O5]o = 4.0 M
t = 155.0 s
use integrated rate law for 1st order reaction
ln[N2O5] = ln[N2O5]o - k*t
ln[N2O5] = ln(4) - 3.63*10^-2*155
ln[N2O5] = 1.3863 - 3.63*10^-2*155
ln[N2O5] = -4.2402
[N2O5] = 1.44*10^-2 M
Answer: 1.44*10^-2 M
2)
Given:
k = 0.0363 s-1
use relation between rate constant and half life of 1st order reaction
t1/2 = (ln 2) / k
= 0.693/(k)
= 0.693/(3.63*10^-2)
= 19.09 s
Answer: 19.1 s