Ch.13 - Chemical KineticsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Additional Problems
Which of the following is NOT TRUE about the behavior of a catalyst. A) A catalyst accelerates a reaction. B) A catalyst is consumed in an earlier elementary step and then regenerated in a later elementary step. C) A catalyst does not appear in the overall balanced reaction. D) A catalyst shifts the reaction equilibrium so that the products become more favored. E) A catalyst does not have to be in the same phase as the reactants.
What is NOT true for a catalyst? 1. A catalyst is not consumed in chemical reactions. 2. A catalyst can convert an endothermic reaction into an exothermic reaction. 3. A catalyst may be used in the solid, liquid or gaseous phase. 4. A catalyst increases the rate of a chemical reaction by decreasing activation energy.
Which statement most accurately describes the behavior of catalyst? (A) A catalyst increases the ΔG of a reaction and hence the forward rate. (B) A catalyst reduces ΔH of a reaction and hence the temperature needed to produce products. (C) A catalyst reduces the activation energy for a reaction and increases the rate of a reaction. (D) A catalyst increases the equilibrium constant and final product concentrations.
Which one of the following statements about the effect of a catalyst on a reaction is NOT TRUE? (a) A catalyst has no effect on the equilibrium composition of the reaction. (b) A catalyst increases the value of k for a reaction. (c) When a reaction is catalyzed, both forward and reverse reactions are accelerated. (d) When a catalyst speeds up a reaction, the rate law stays the same. (e) A catalyst provides an alternate, lower energy pathway for a reaction.
Which of the following correctly describes or depicts a homogenous catalyst? a) The reactants and the catalyst are in the same phase b) A reaction with an aqueous phase and an organic phase in the same reaction vessel c) An aqueous reaction with a solid platinum catalyst d) Platinum metal with gaseous methane e) A reaction of N2 and H2 at 25 degrees Celsius with a Fe catalyst
A catalyst increases the rate of a reaction by (A) changing the mechanism of the reaction. (B) increasing the activation energy of the reaction. (C) increasing the concentration of one or more of the products. (D) decreasing the difference in relative energy of the reactants and products.
Identify a heterogeneous catalyst.   A) CFCs with ozone B) Pd in H2 gas C) KI dissolved in H2O2 D) H2SO4 (aq) with concentrated HCl E) H3PO4 (aq) with an alcohol
Which one of the following statements regarding catalysts is  FALSE? (a) A catalyst is a chemical agent that speeds up the rate of a given reaction. (b) A catalyst may be in the same phase or a different phase than the reactants and products. (c) A catalyst has no effect on the mechanism of a reaction. (d) A catalyst has no effect on ΔG of K of the reaction. (e) Effective catalysis can be achieved even when the amount of catalyst is small compared to the amount of reactants.
Is it reasonable to say that enzymes lower the energy of the transition state for a reaction?
What is a catalyst?
What is the difference between a homogeneous and a heterogeneous catalyst?
Do catalysts affect the overall enthalpy change for a reaction, the activation energy, or both?
What role does adsorption play in the action of a heterogeneous catalyst?
Many metallic catalysts, particularly the precious-metal ones, are often deposited as very thin films on a substance of high surface area per unit mass, such as alumina (Al2O3) or silica (SiO2).Why is this an effective way of utilizing the catalyst material compared to having powdered metals?
The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to: l NO2(g) + SO2(g)NO( g ) + SO3 ( g )2NO(g) + O2(g)2NO2(g) Is this an example of homogeneous catalysis or heterogeneous catalysis?
In general, which type of catalyst, homogeneous or heterogeneous, will be easier to recover from the reaction mixture?
What is a catalyst? How does a catalyst increase the rate of a chemical reaction?
Explain the difference between homogeneous catalysis and heterogeneous catalysis.
What are the four basic steps involved in heterogeneous catalysis?
What will happen to the rates of the forward and reverse reactions when a catalyst is added?a. Forward rate increases; reverse rate decreases.b. Both forward and reverse rates increase.c. Both forward and reverse rates decrease.d. Forward rate decreases; reverse rate increases.
A catalyst facilitates a reaction by a) shifting the position of the equilibrium of the reaction. b) lowering the activation energy of the reaction. c) making the reaction more exothermic. d) increasing the activation energy for the reverse reaction. e) decreasing the temperature at which the reaction will proceed spontaneously. 
Which of the following statements is incorrect concerning a catalyst? A) A catalyst may appear in the rate law for a reaction. B) A catalyst alters the equilibrium distribution of reactants and products. C) A catalyst decreases the activation energy of a reaction. D) A catalyst provides an alternative reaction mechanism. E) There is no net consumption of a catalyst in a reaction.
The effect of a catalyst in a reaction is to:a. Increase the rate of the forward reaction, but not affect the reverse rate of the reaction. b. Decrease the value of Ea for the reaction. c. Increase the value of Keq for the reaction. d. Make  ΔH for the reaction more negative. e. Increase the average kinetic energy of the reactants. 
 Which statements below are always true regarding the addition of a catalyst to a reaction:I. the catalyst is in the same state as the reactantsII. the catalyst lowers the activation energy in a reactionIII. the catalyst raises the value for the rate constant, kA. only IB. only IIC. only IIID. II and IIIE. All three statements
The enzyme urease catalyzes the reaction of urea, (NH2CONH2), with water to produce carbon dioxide and ammonia. In water, without the enzyme, the reaction proceeds with a first-order rate constant of 4.15 x 10-5 s–1 at 100˚C. In the presence of the enzyme in water, the reaction proceeds with a rate constant of 3.4 x 104 s–1 at 21˚C. If the rate of the catalyzed reaction were the same at 100˚C as it is at 21˚C, what would be the difference in the activation energy between the catalyzed and uncatalyzed reactions? In actuality, what would you expect for the rate of the catalyzed reaction at 100˚C as compared to that at 21˚C?On the basis of your answers, what can you conclude about the difference in activation energies for the catalyzed and uncatalyzed reactions?
Account for the increase in reaction rate brought about by a catalyst.
Compare the functions of homogeneous and heterogeneous catalysts.
Consider this scenario and answer the following questions: Chlorine atoms resulting from decomposition of chlorofluoromethanes, such as CCl2F2, catalyze the decomposition of ozone in the atmosphere. One simplified mechanism for the decomposition is:O3 O2 + OO3 + Cl ⟶ O2 + ClOClO + O ⟶ Cl + O2(a) Explain why chlorine atoms are catalysts in the gas-phase transformation: 2 O3 ⟶ 3 O2
Consider this scenario and answer the following questions: Chlorine atoms resulting from decomposition of chlorofluoromethanes, such as CCl2F2, catalyze the decomposition of ozone in the atmosphere. One simplified mechanism for the decomposition is:O3  O2 + OO3 + Cl ⟶ O2 + ClOClO + O ⟶ Cl + O2(b) Nitric oxide is also involved in the decomposition of ozone by the mechanism:O3   O2 + OO3 + NO ⟶ NO2 + O2NO2 + O ⟶ NO + O2Is NO a catalyst for the decomposition? Explain your answer.
For each of the following pairs of reaction diagrams, identify which of the pair is catalyzed:
For each of the following pairs of reaction diagrams, identify which of the pair is catalyzed:
For each of the following pairs of reaction diagrams, identify which of the pairs is catalyzed:
For each of the following pairs of reaction diagrams, identify which of the pairs is catalyzed:
Is each of these statements true? If not, explain why.(i) A catalyst increases the rate by increasing collision frequency.
Is each of these statements true? If not, explain why.(l) The activation energy of a reaction is lowered by a catalyst.
Is each of these statements true? If not, explain why.(m) For most reactions, ΔHrxn is lowered by a catalyst.
Like any catalyst, palladium, platinum, or nickel catalyzes both directions of a reaction: addition of hydrogen to (hydrogenation) and its elimination from (dehydrogenation) carbon double bonds. Which variable determines whether an alkene will be hydrogenated or dehydrogenated?
Like any catalyst, palladium, platinum, or nickel catalyzes both directions of a reaction: addition of hydrogen to (hydrogenation) and its elimination from (dehydrogenation) carbon double bonds. Which reaction requires a higher temperature?
Like any catalyst, palladium, platinum, or nickel catalyzes both directions of a reaction: addition of hydrogen to (hydrogenation) and its elimination from (dehydrogenation) carbon double bonds. How can all-trans fats arise during hydrogenation of fats that contain some double bonds with a cis orientation?
Many heterogeneous catalysts are deposited on high surface-area supports. Why is a large surface area important in heterogeneous catalysis?
While developing a catalytic process to make ethylene glycol from synthesis gas (CO + H2), a chemical engineer findsthe rate to be fourth order with respect to gas pressure. The uncertainty in the pressure reading is 5%. When the catalyst is modified, the rate increases by 10%. If you were the company patent attorney, would you file for a patent on this catalyst modification? Explain.
The scenes depict four initial reaction mixtures for the reaction of A (blue) and B (yellow), with and without a solid present (gray cubes). The initial rate, –d[A]/dt (in mol/L·s), is shown, with each sphere representing 0.010 mol and the container volume at 0.50 L.Do the gray cubes have a catalytic effect? Explain.
One of the many remarkable enzymes in the human body is carbonic anhydrase, which catalyzes the interconversion of carbonic acid with carbon dioxide and water. If it were not for this enzyme, the body could not rid itself rapidly enough of the CO2 accumulated by cell metabolism. The enzyme catalyzes the dehydration (release to air) of up to 107 CO2 molecules per second.Which component of this description corresponds to the term enzyme?
Which statement is true regarding the function of a catalyst in a chemical reaction?a) A catalyst increases the rate of a reaction.b) A catalyst provides an alternate mechanism for the reaction.c) A catalyst is not consumed by the reaction.d) All of the above are true.
Suppose that the reaction A → products is exothermic and has an activation barrier of 75 kJ/mol. Draw an energy curve showing the effect of a catalyst.
Platinum nanoparticles of diameter ~2 nm are important catalysts in carbon monoxide oxidation to carbon dioxide. Platinum crystallizes in a face-centered cubic arrangement with an edge length of 3.924 Å.Which size of nanoparticle (2.0 nm or 5.0 nm) would you expect to be more catalytically active and why?
One of the concerns about the use of Freons is that they will migrate to the upper atmosphere, where chlorine atoms can be generated by the following reaction:Chlorine atoms can act as a catalyst for the destruction of ozone. The activation energy for the reactionis 2.1 kJ/mol. Which is the more effective catalyst for the destruction of ozone, Cl or NO? Ea for the uncatalyzed reaction O3 (g) + O(g) → 2O2 (g) is 14.0 kJ. Ea for the same reaction when catalyzed is 11.9 kJ. 
The decomposition of NH3 to N2 and H2 was studied on two surfaces:Without a catalyst, the activation energy is 335 kJ/mol.a. Which surface is the better heterogeneous catalyst for the decomposition of NH 3? Why?
A certain compound, A, reacts to form products according to the reaction A → P. The amount of A is measured as a function of time under a variety of different conditions and the tabulated results are shown here:Time (s)25.0 oC [A] (M)35.0 oC [A] (M)45.0 oC [A] (M)01.0001.0001.000100.7790.6620.561200.5910.4610.312300.4530.3060.177400.3380.2080.100500.2590.1360.057600.2000.0930.032The same reaction is conducted in the presence of a catalyst, and the following data are obtained:Time (s)25.0 oC [A] (M)35.0 oC [A] (M)45.0 oC [A] (M)01.0001.0001.0000.10.7240.6680.5980.20.5110.4330.3410.30.3750.2910.2020.40.2750.1900.1190.50.1980.1220.0710.60.1410.0800.043What effect does a catalyst have on the rate of the reaction?
A certain compound, A, reacts to form products according to the reaction A → P. The amount of A is measured as a function of time under a variety of different conditions and the tabulated results are shown here:Time (s)25.0 oC [A] (M)35.0 oC [A] (M)45.0 oC [A] (M)01.0001.0001.000100.7790.6620.561200.5910.4610.312300.4530.3060.177400.3380.2080.100500.2590.1360.057600.2000.0930.032The same reaction is conducted in the presence of a catalyst, and the following data are obtained:Time (s)25.0 oC [A] (M)35.0 oC [A] (M)45.0 oC [A] (M)01.0001.0001.0000.10.7240.6680.5980.20.5110.4330.3410.30.3750.2910.2020.40.2750.1900.1190.50.1980.1220.0710.60.1410.0800.043How does the activation energy of the catalyzed reaction compare with the activation energy for the reaction when the catalyst isn't present?
Which of the following statement(s) is(are) true?a. The half-life for a zero-order reaction increases as the reaction proceeds.b. A catalyst does not change the value of the rate constant.c. The half-life for a reaction, aA → products, that is first order in A increases with increasing [A]  0.d. The half-life for a second-order reaction increases as the reaction proceeds.
How are the following aspects of a reaction affected by the addition of a catalyst?