AP CHEM 5.3

After a certain pesticide compound is applied to crops, its decomposition is a first-order reaction with a half-life of 5656 days. What is the rate constant, kk, for the decomposition reaction?

0.012day−1

X → products Pure substance X decomposes according to the equation above. Which of the following graphs indicates that the rate of decomposition is second order in X ?

1/x going up

The reaction between C25H30N3+ (aq) and OH-(aq), as represented above, is first order with respect to C25H30N3+ (aq) in the presence of excess OH-(aq). A 10.0 mL sample of 0.10 M NaOH(aq) is mixed with a 10.0 mL sample of 2.5 x 10-5 M C25H30N3+(aq). A 5.0 mL sample of the mixture is quickly transferred to a clean cuvette and placed in a spectrophotometer, and the progress of the reaction is measured. The data are given in the table below. Approximately how long did it take for 75 percent of the initial amount of C25H30N3+ (aq) to react?

300 s

The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. The concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied?

It is first order in [X].

X → Products A student studied the kinetics of the reaction represented above by measuring the concentration of the reactant, X, over time. The data are plotted in the graph below. Which of the following procedures will allow the student to determine the rate constant, k , for the reaction?

Plot ln [X] versus time and determine the magnitude of the slope.

The data from a study of the decomposition of NO2(g) to form NO(g) and O2(g) are given in the table above. Which of the following rate laws is consistent with the data?

Rate=k[NO2]2

A reaction was observed for 20 days and the percentage of the reactant remaining after each day was recorded in the table above. Which of the following best describes the order and the half-life of the reaction?

Reaction order: 1st half life : 3

A sample of N2O5 was placed in an evacuated container, and the reaction represented above occurred. The value of PN2O5, the partial pressure of N2O5(g), was measured during the reaction and recorded in the table below. Which of the following correctly describes the reaction?

The decomposition of N2O5 is a first-order reaction.

2 H2O2(aq) → 2 H2O(l) + O2(g) ΔH° = −196 kJ/molrxn The decomposition of H2O2(aq) is represented by the equation above. A student monitored the decomposition of a 1.0 L sample of H2O2(aq) at a constant temperature of 300. K and recorded the concentration of H2O2 as a function of time. The results are given in the table below. Which of the following statements is a correct interpretation of the data regarding how the order of the reaction can be determined?

The reaction is first order if the plot of ln [H2O2] versus time is a straight line.

Which of the following best identifies the rate constant kk for the reaction based on the information in the plot of ln[H2O2] versus time (t) ?

k=−(slope of plot)