University of Texas, Arlington CHEM 1442 Chapter 13 Questions Deriving the Rate Law 1)The following rate data were measured for the reaction: A + B ? C + D

University of Texas, Arlington

CHEM 1442

Chapter 13 Questions

Deriving the Rate Law

1)The following rate data were measured for the reaction: A + B ? C + D. What is                                                                   the rate law?

Initial [A]                                        Initial [B]                              Initial Rate (M/s)

2. What is the rate equation for the elementary reaction: 2 NO2 ? O2 + N2O2 ?
   1. Rate = k[O2] (b) Rate = k[N2O2] (c) Rate = k[NO2] (d) Rate = k[NO2]2

Using the integrated rate law equations for first and second order reactions

3. SO2Cl2 (g) decomposes in a first order reaction to produce SO2(g) and Cl2(g). From the date below relating the partial pressure of SO2Cl2(g) to time, determine the rate constant for the reaction.

SO2Cl2(atm)                                               Time, Sec

1.000                                                             0

0.803                                                             10,000

(a) 2.2 X 10-5/s  (b) 9.5 X 10-6/s (c) 8.0 X 10-5/s  (d) 1.0 X 10-4/s (e) 2.0 X 10-5/s

4. The decomposition of nitrosyl chloride is a bimolecular reaction involving two nitrosyl chloride molecules and therefore is second order. If the rate constant for the reaction at room temperature is 0.020 liter mol-1s- 1 , what will be the concentration of NOCl be after 2 minutes if the initial concentration was .200 M? (a) . 14 M (b) .07 M (c) .09 M (d) .12 M (e) .16 M

5. The decomposition of nitrogen dioxide to produce nitric oxide and oxygen is a second-order reaction. For this reaction, a plot of which variables should produce a straight line?

6. A certain first order reaction is 65% complete in 45 s. What is the half-life of this reaction? (a)5s  (b) 15s  (c) 22s  (d) 30s  (e) 44s

The Arrhenius Equation

7. The rate constant for a reaction increases from 10 s-1 to 100s-1 when the temperature increases from 300 K to 400 K. What is the activation energy for the reaction in kJ/mol ? (R = 8.314 J/mol K )

(a) 23  (b) 12.7 (c) 5  (d) 18.3  (e) 45.6

Rate Law Questions without using the equations

8. The rate equation for the overall reaction 2 P + R ?Q is : Rate = k[P]2 . If the                concentration of P is halved and the concentration of R is doubled, then the initial             rate of the reaction:
   1. is increased by a factor of 8 (b) is increased by a factor of 4 (c) is decreased by a factor of 4 (d) is decreased by a factor of 8 (e) remains the same

9.         The combustion of ammonia (NH3) given by the following: 4NH3 + 5O2 ?                           4NO + 6 H2O. If ammonia is burning at the rate of 6 mole/s. what is the rate of                                            formation of water in moles/s?

(a)          4 (b) 6  (c) 7.5 (d) 9  (e) 12

Mechanisms

10. Consider the following reaction: H₂(g) + 2ICl(g) ? 2HCl(g) + I₂(g)

The rate law for this reaction was determined to be R = k [H₂][ICl]. Is the following proposed mechanism consistent with the above data?

H₂(g) + ICl(g) ? HI(g) + HCl(g) (fast)

HI(g) + ICl(g) ? HCl(g) + I₂(g)                      (slow)