Kinetics Quiz #2 Factors that Change the Reaction Rate

1. Which of the following reactions is the slowest at room temperature?

A. Zn_(s) + S_(s) → ZnS_(s)

B. Ba2+(aq) + SO42-(aq) → BaSO4(s)

C. NH_3(g) + HCl_(g) → NH₄Cl_(g)

D. 2 Ag⁺_(aq) + CO₃^2-_(aq) → Ag₂CO_3(s)

2. Dust particles suspended in the air inside unheated grain elevators can sometimes react explosively because the dust particles have a:

A. High kinetic energy

B. High activation energy

C. Catalytic effect on the reaction

D. Large surface area for the reaction

3. Consider the following reaction: 2H₂O_2(aq) → 2 H₂O_(t) + O_2(g)

When 1.0 g of KI is added to the H₂O₂, bubbles of O₂ are produced at an increased rate. When the reaction is complete, the mass of KI is 1.0 g. The KI is a

A. Product

B. Catalyst

C. Reactant

D. Reaction Intermediate

4. Consider the following factors:

I. Concentration of reactants.

II. Temperature of reactants.

III. Surface area of reactants.

The factors that affect the rate of a chemical reaction between two gases are

A. I and II only

B. I and III only

C. II and III only.

D. I, II, and III

5. Consider the following reactions:

I. N_2(g) + O_2(g) → 2NO_(g)

II. 2Mg_{(s) +} O_2(g) → 2MgO_(s)

III. CaCO_{3(s) +} 2H⁺_(aq) → Ca²⁺_(aq) + H₂O_(l) + CO_2(g)

Increasing the surface area will increase the reaction rate in

A. II only

B. I and III only

C. II and III only

D. I, II and III

6. An untreated sugar cube does not burn when held over a lighted match. A sugar cube coated with cigarette ash readily ignites and burns. All of the cigarette ash remains after the reaction. The factor that caused this change in rate is the

A. Nature of reactants

B. Presence of a catalyst

C. Increase in surface area

D. Increase in concentration

7. Which combination of factors will affect the rate of the following reaction?

Zn_{(s) +} 2HCl _(aq) → ZnCl_2(aq) + H_2(g)

A. Temperature and surfaces only

B. Temperature and concentration only

C. Concentration and surface area only

D. Temperature, concentration, and surface area

8. A catalyst increases the rate of a reaction by

A. Increasing the concentration of the reactant(s)

B. Decreasing the concentration of the reactant(s)

C. Increasing the activation energy of the overall reaction

D. Decreasing the activation energy of the overall reaction

9. Consider the following reaction:

2MnO₄^-_(aq) + 5C₂O₄^2-_(aq) + 16H⁺_(aq) ® 2Mn²⁺_(aq) + 10CO_2(g) + 8H₂O_(l)

The rate of decomposition of the oxalate ion is increased by

A. Adding NaOH

B. Removing CO2

C. Adding a catalyst

D. Decreasing the pressure.

10. Which of the following factors affect the rates of both homogeneous and heterogeneous reactions

I. Nature of reactants

II. Presence of a catalyst

III. Temperature of system

IV Concentration of reactants

A. I and IV only

B. II and III only.

C. II, III and IV only

D. I, II, III and IV

11. Which of the following factors affects the rate of heterogeneous reactions only.

A. Nature of reactants

B. Temperature of system

C. Surface area of reactants

D. Concentration of reactants

12. Consider the following reaction: 2S_{(s) +} 30_2(g) → 2SO_3(g) + heat

The rate of this reaction could be increased by

A. Decreasing temperature

B. Adding a catalyst

C. Increasing the concentration of S_(s)

D. Increasing the concentration of SO_3(g)

13. 6.0 g of Mg reacts with some HCl in two different experiments. The reaction for both was:

Mg_{(s) +} 2HCl_(aq) ® MgCl_2(aq) + H_2(g)

In the first experiment, it took 6.2 minutes for all the Mg to react. In the second experiment, it took 10.8 minutes for all the Mg to react. Which of the following could explain the change in rate in the second experiment?

A. A catalyst was added

B. The Mg was powdered

C. The H₂ was decreased

D. The temperature was decreased

14. Which of the following reactions is most likely to proceed at the greatest rate?

A. Zn_(s) + S_(s) ® ZnS_(s)

B. H_2(g) + I_2(s) ® 2HI_(g)

C. Cu_(s) + Cl_2(g) ® CuCl_2(s)

D. 2KOH_(aq) + H₂SO_4(aq) ® 2H₂O_(l) + K₂SO_4(aq)

15. Consider the following reaction:

Mg_(s) + 2HCl_(aq) ® MgCl_2(aq) + H_2(g)

Which of the following would increase the reaction rate?

A. an increase in pressure

B. an increase in temperature

C. an increase in the concentration of H₂

D. an increase in the concentration of MgCl₂

16. When a candle C₂₀H₄₂ burns, the following reaction occurs:

2C₂₀H_42(s) + 61O_2(g) ® 40CO₂ + 42H₂O_(g)

If the rate of production of CO₂ is 0.49 g/min, what is the rate of oxygen consumption?

A. 0.24 g/min

B. 0.27 g/min

C. 0.36 g/min

D. 0.54 g/min

17. Which of the following properties could best be monitored in order to determine the reaction rate of the above burning candle?

A. mass of C₂₀H₄₂

B. pressure of H₂O

C. surface area of C₂₀H₄₂

D. concentration of C₂₀H₄₂

18. Which of the following factors only affects the rate of heterogeneous reactions?

A. nature of reactants

B. presence of a catalyst

C. temperature of reactants

D. surface area of reactants

19. Consider the following experimental results:

Experiment 1 Experiment 2

Reactants Ca_(s) + HCl_(aq) Zn_(s) + HCl_(aq)

Temperature 20 ⁰C 40 ⁰C

Concentration 1.0 M 2.0 M

Rates Fast Slow

Which factor would account for the faster reaction rate in Experiment 1?

A. temperature

B. surface area

C. nature of reactants

D. solution concentration

20. Consider the following reaction:

2NO_(g) + O_2(g) ® 2NO_2(g)

How could the rate of this reaction be increased?

A. Reduce the pressure

B. Increase the volume

C. Remove some NO_2(g)

D. Increase the temperature

21. Which factor explains why coal dust is explosive?

A. temperature

B. surface area

C. concentration

D. addition of catalyst

22. Which factor explains why potassium generally reacts faster than magnesium?

A. surface area

B. temperature

C. concentration

D. nature of reactants

23. Which factor explains why gasoline vapour is explosive?

A. temperature

B. surface area

C. concentration

D. nature of the reactant