5 Written questions
5 Matching questions
- For which of the following hypothetical rate laws would the units of the rate constant have the general form M⋅time−1?
a. rate = k
b. rate = k[A]
c. rate = k[A]3
d. rate = k[A]2
e. rate = k[A]4
- At 300 K the reaction below obeys the rate law Rate = k[NOCl]2 where k = 2.8 × 10−5 M−1•s−1.
2NOCl → 2NO + Cl2
Suppose 1.0 mole of NOCl is introduced into a 2.0-liter container at 300 K. Evaluate the half-life of the reaction.
a. 2.6 × 103 seconds
b. 3.6 × 104 seconds
c. 2.4 × 104 seconds
d. 1.1 × 103 seconds
e. 4.0 × 104 seconds
- Which of the following statements regarding the rate constant in the rate law expression is incorrect?
a. Its value increases with temperature.
b. Its value is independent of initial concentration at a given temperature.
c. Its units depend on the overall order of reaction.
d. Its value is experimentally determined.
e. The larger its value, the slower the reaction rate.
- Evaluate the specific rate constant at the temperature at which the data were collected. The rate-law expression is rate = k[NO]2[H2].
H2(g) + NO(g) → N2O(g) + H2O(g)
Experiment Initial [NO] (M) Initial [H2] (M) Initial Rate (M•s−1)
1 0.30 0.35 2.835 × 10−3
2 0.60 0.35 1.134 × 10−2
3 0.60 0.70 2.268 × 10−2
a. 9.4 × 10−3 M−2•s−1
b. 2.7 × 10−2 M−2•s−1
c. 1.6 × 10−4 M−2•s−1
d. 8.1 × 10−3 M−2•s−1
e. 9.0 × 10−2 M−2•s−1
- Reaction rates increase with increasing temperature because ____.
a. the activation energy increases
b. larger molecules collide more frequently
c. the energy of the transition state is lowered
d. the activation energy is decreased
e. a greater fraction of molecules possess the activation energy when they collide
- a e. 9.0 × 10−2 M−2•s−1
- b b. 3.6 × 104 seconds
- c e. a greater fraction of molecules possess the activation energy when they collide
- d e. The larger its value, the slower the reaction rate.
- e a. rate = k
5 Multiple choice questions
- a. 21 min
- a. 0.0016 mol/L
- e. 0.057 mol/L•s
- e. 6.4 × 10−3 M•s−1
- a. increasing the temperature
5 True/False questions
Which idea listed below is not a part of the collision theory of reaction rates?
a. Molecules must be properly oriented when they collide to react.
b. Molecules must collide to react.
c. Molecules must collide with enough kinetic energy to overcome the potential energy stabilization of the bonds.
d. Effective collisions result in a chemical reaction.
e. All molecular collisions result in a reaction. → d. 1 and 2
Suppose a reaction A + B → C occurs at some initial rate at 25°C. Which response includes all of the changes below that could increase the rate of this reaction?
I. lowering the temperature
II. adding a catalyst
III. increasing the initial concentration of B
d. I and II
e. II and III → e. II and III
The rate constant for a first-order reaction is 0.58 s−1 at 25°C. At what temperature would the rate constant have a value of 0.75 s−1? The activation energy is 84 kJ/mol and the universal gas constant = 8.314 J/mol•K.
c. 298 K
d. 301 K
e. 310 K → b. 300°K
Of the following questions, which ones are thermodynamic rather than kinetic concepts?
I. Can substances react when they are put together?
II. If a reaction occurs, how fast will it occur?
III. What is the mechanism by which the reaction occurs?
IV. If substances react, what energy changes are associated with the reaction?
a. I and III
b. II and IV
c. I and IV
d. II and III
e. I, III, and IV → c. I and IV
Which of the following expressions does not represent a proper expression for the rate of this reaction?
2A + 3B → F + 2G
ANS: A → -DeltaA/Dt