5 Written Questions
5 Matching Questions
- Given the following data for the reaction below.
NH4+ + NO2− → N2 + 2H2O
Trial [NH4+] [NO2−] Rate
1 0.010 M 0.030 M 0.020 M/s
2 0.015 0.030 0.030
3 0.010 0.015 0.005
The rate law for the reaction is
a. rate = k[NH4+][NO2−]
b. rate = k[NH4+]2[NO2−]
c. rate = k[NH4+][NO2−]2
d. rate = k[NH4+]2[NO2−]2
e. None of these
- Suppose the activation energy of a certain reaction is 250 kJ/mol. If the rate constant at T1 = 300 K is k1, and the rate constant at T2 = 320 K is k2, then k2/k1 = ____. (The universal gas constant = 8.314 J/mol•K.)
a. 3 × 10−29
e. 3 × 1028
- Consider the following rate law expression: rate = k[A]2[B]. Which of the following is not true about the reaction having this expression?
a. The reaction is first order in B.
b. The reaction is overall third order.
c. The reaction is second order in A.
d. A and B must both be reactants.
e. Doubling the concentration of A doubles the rate.
- Which of the following is/are expected to affect the rate of a chemical reaction?
1. Increasing the reaction temperature.
2. Addition of a catalyst.
3. Stirring a well mixed reaction solution.
a. 1 only
b. 2 only
c. 3 only
d. 1 and 2
e. 1, 2, and 3
- Which response below is not an example of how the nature of reactants affects the rate of reaction?
a. Graphite burns faster than diamond under equal conditions.
b. Coal dust burns faster than large chunks of coal.
c. Magnesium reacts faster in higher concentrations of HCl(aq).
d. Calcium reacts faster in water than magnesium.
e. White phosphorus reacts explosively on contact with air; red phosphorus does not.
- a d. 525
- b c. rate = k[NH4+][NO2−]2
- c d. 1 and 2
- d e. Doubling the concentration of A doubles the rate.
- e c. Magnesium reacts faster in higher concentrations of HCl(aq).
5 Multiple Choice Questions
- b. M−2•s−1
- d. Their values get larger as the temperature is increased.
- e. 0.057 mol/L•s
- c. must be able to reach the activation energy
- e. The slow step will only include reactants listed in the overall chemical equation.
5 True/False Questions
At a certain temperature the reaction below obeys the rate-law expression rate = (1.14 × 10−3 M−1•s−1)[B]2. If 5.00 mol of B is initially present in a 1.00-L container at that temperature, how long would it take for 2.00 mol of B to be consumed at constant temperature?
2B → C + D
a. 224 s
b. 87.5 s
c. 46.0 s
d. 73.0 s
e. 58.5 s → e. 58.5 s
Compounds A and B react to form C and D in a reaction that is found to be second-order overall and second-order in B. The rate constant at 30°C is 0.622 liter per mole per minute.
A + B → C + D
How many minutes does it take 4.0 × 10−2 M B (mixed with excess A) to be reduced to 3.3 × 10−2 M B?
a. 1.4 min
b. 3.6 min
c. 5.0 min
d. 6.4 min
e. 8.5 min → a. increasing the temperature
Which is not an example of the effect of subdivision of the reactant on the rate of chemical reaction?
a. Violent explosions that occur in grain elevators.
b. A container of flammable liquid will burn on the surface but allowed to vaporize will burn explosively.
c. A chunk of iron takes months to rust completely while iron wool will rust in days.
d. Some metals may be fused (welded) with minimal loss while their powders will burn in a flame.
e. The Grand Canyon was created by dissolution by water over millions of years. → e. The Grand Canyon was created by dissolution by water over millions of years.
Which term is incorrectly matched with its description?
a. Activation Energy / kinetic energy required for reaction to occur
b. Transition State / short-lived high-energy intermediate state
c. Effective Collision / molecular collision resulting in a reaction
d. Net energy change of the reaction / Ea, forward − Ea, reverse
e. Endothermic Reaction / reaction having Ea, reverse > Ea, forward → e. The Grand Canyon was created by dissolution by water over millions of years.
If the half-life of a reaction is independent of concentration, the reaction is:
a. Zero order
b. First order
c. Second order
d. Zero and first order
e. First and second order → a. Zero order