1.Nitric oxide and nitrogen dioxide are found in photochemical smog. Nitrogen di
ID: 580910 • Letter: 1
Question
1.Nitric oxide and nitrogen dioxide are found in photochemical smog. Nitrogen dioxide is formed from nitrogen monoxide in the exhaust of automobile engines. A possible mechanism for this reaction is given below. What is the rate law predicted by the mechanism?
Reaction: 2NO(g) + O2(g) ® 2NO2(g)
Step 1 (fast): NO + NO ® N2O2
Step 2 (slow): N2O2 + O2 ® 2NO2
Rate = k[NO]2
Rate = k[NO]2[O2]
Rate = k[NO][O2]
Rate = k[NO2]2
2.Which of the following statements must be true of a catalyst in a reaction mechanism?
I. Is consumed in an elementary step.
II. Is regenerated in an elementary step after it is consumed.
III. Is included in the overall balanced reaction equation.
I only
II only
III only
I, II, and III
I and II only
a.
Rate = k[NO]2
b.Rate =
c.Rate = k[NO]2[O2]
d.Rate = k[NO][O2]
e.Rate = k[NO2]2
Explanation / Answer
1.Nitric oxide and nitrogen dioxide are found in photochemical smog. Nitrogen dioxide is formed from nitrogen monoxide in the exhaust of automobile engines.
the rate law of the following reaction is C. rate = k[O2][NO]2 correct answer
overall reaction order = 3
units of rate constant = M-2 s-1
Reaction: 2NO(g) + O2(g) ® 2NO2(g)
Step 1 (fast): NO + NO ® N2O2
Step 2 (slow): N2O2 + O2 ® 2NO2
2. the following statements must be true for a catalyst in a reaction mechanism
Yes, a catalyst can be included in a rate law. That's because, most reactions occur in a series of step and the rate is based on the "rate determining step", which is the slowest step. A catalyst may be a reactant in the rate determining step, and a product in a subsequent step. Therefore, the catalyst is not included in the overall reaction.
But a catalyst need not always be in the rate law. The rate law is usually based on the rate determining step.
Correct answer is E.i.e. I and II only
I. Is consumed in an elementary step.
II. Is regenerated in an elementary step after it is consumed.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.