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Practice Exam: Paper 1
Topic 6: Kinetics
SL
1. Which statements describe the action of a catalyst? I. It does not alter the โ H for a reaction. II. It increases the E a for the reaction. III. It alters the mechanism (pathway) of a reaction. A. I and II only C. II and III only B. I and III only D. I, II and III 2. Consider the reaction between gaseous iodine and gaseous hydrogen. I 2 (g) + H 2 (g) 2HI(g) โ H O^ = โ9 kJ Why do some collisions between iodine and hydrogen not result in the formation of the product? A. The I 2 and H 2 molecules do not have sufficient energy. B. The system is in equilibrium. C. The temperature of the system is too high. D. The activation energy for this reaction is very low. 3. Curve X on the graph below shows the volume of oxygen formed during the catalytic decomposition of a 1. mol dmโ3^ solution of hydrogen peroxide. 2H 2 O 2 (aq) โ O 2 (g) + 2H 2 O(l) Which change would produce the curve Y? A. Adding water C. Using a different catalyst B. Adding some 0.1 mol dmโ3^ hydrogen peroxide solution D. Lowering the temperature SL Score / HL Score /
4. At 25 ยฐC, 200 cm^3 of 1.0 mol dmโ3^ nitric acid is added to 5.0 g of magnesium powder. If the experiment is repeated using the same mass of magnesium powder, which conditions will result in the same initial reaction rate? Volume of HNO 3 / cm^3 Concentration of HNO 3 / mol dmโ Temperature / ยฐC A. 200 2.0 25 B. (^200) 1.0 50 C. 100 2.0 25 D. (^100) 1.0 25 5. Sodium carbonate and hydrochloric acid react according to the equation below. Na 2 CO 3 (s) + 2HCl(aq) โ CO 2 (g) + 2NaCl(aq) + H 2 O(l) Which conditions will produce the fastest initial rate with 2.0 g of powdered sodium carbonate? A. 100 cm^3 of 1.0 mol dmโ3^ hydrochloric acid at 323 K B. 50 cm^3 of 2.0 mol dmโ3^ hydrochloric acid at 323 K C. 100 cm^3 of 1.0 mol dmโ3^ hydrochloric acid at 348 K D. 50 cm^3 of 2.0 mol dmโ3^ hydrochloric acid at 348 K 6. Under which conditions will the reaction between 1.0 g calcium carbonate and excess hydrochloric acid be the fastest? Assume that all reactions are carried out at the same temperature. A. One large piece of calcium carbonate and 2 mol dmโ3^ hydrochloric acid B. One large piece of calcium carbonate and 1 mol dmโ3^ hydrochloric acid C. Powdered calcium carbonate and 2 mol dmโ3^ hydrochloric acid D. Powdered calcium carbonate and 1 mol dmโ3^ hydrochloric acid 7. Powdered manganese(IV) oxide, MnO 2 (s), increases the rate of the decomposition reaction of hydrogen per- oxide, H 2 O 2 (aq). Which statements about MnO 2 are correct? I. The rate is independent of the particle size of MnO 2. II. MnO 2 provides an alternative reaction pathway for the decomposition with a lower activation energy. III. All the MnO 2 is present after the decomposition of the hydrogen peroxide is complete. A. I and II only C. II and III only B. I and III only D. I, II and III
11. A piece of zinc was added to aqueous nitric acid and the volume of hydrogen gas produced was measured every minute. The results are plotted on the graph below. Which graph would you expect if the same mass of powdered zinc was added to nitric acid with the same concentration?
12. Which changes increase the rate of the reaction below? C 4 H 10 (g) + Cl 2 (g) โ C 4 H 9 Cl(l) + HCl(g) I. Increase of pressure II. Increase of temperature III. Removal of HCl(g) A. I and II only B. I and III only C. II and III only D. I, II and III 13. Which quantities in the enthalpy level diagram are altered by the use of a catalyst? A. I and II only B. I and III only C. II and III only D. I, II and III 14. The formation of nitric acid, HNO 3 (aq), from nitrogen dioxide, NO 2 (g), is exothermic and is a reversible re- action. 4NO 2 (g) + O 2 (g) + 2H 2 O(l) 4HNO 3 (aq) What is the effect of a catalyst on this reaction? A. It increases the yield of nitric acid. B. It increases the rate of the forward reaction only. C. It increases the equilibrium constant. D. It has no effect on the equilibrium position.
18. What is the function of iron in the Haber process? A. It shifts the position of equilibrium towards the products. B. It decreases the rate of the reaction. C. It provides an alternative reaction pathway with a lower activation energy. D. It reduces the enthalpy change of the reaction. 19. Hydrochloric acid is reacted with large pieces of calcium carbonate, the reaction is then repeated using cal- cium carbonate powder. How does this change affect the activation energy and the collision frequency? Activation energy Collision frequency A. increases increases B. (^) stays constant increases C. increases stays constant D. (^) stays constant stays constant 20. Which statement is true about using sulfuric acid as a catalyst in the following reaction? CH 3 โCOโCH 3 (aq) + I 2 (aq) --------> CH 3 โCOโCH 2 โI(aq) + HI(aq) I. The catalyst increases the rate of reaction. II. The catalyst lowers the activation energy for the reaction. III. The catalyst has been consumed at the end of the chemical reaction. A. I and II only C. II and III only B. I and III only D. I, II and III 21. Excess magnesium, was added to a beaker of aqueous hydrochloric acid. A graph of the mass of the beaker and contents was plotted against time (line 1). What change in the experiment could give line 2? A. The same mass of magnesium in smaller pieces C. A lower temperature B. The same volume of a more concentrated hydrochloric acid D. A more accurate instrument to measure time
HL
1. Bromine and nitrogen(II) oxide react according to the following equation. Br 2 (g) + 2NO(g) โ 2NOBr(g) Which rate equation is consistent with the experimental data? [Br 2 ] / mol dmโ3^ [NO] / mol dmโ3^ Rate / mol dmโ3^ sโ 0.10 0.10 (^) 1.0 ร 10 โ 0.20 0.10 (^) 4.0 ร 10 โ 0.20 0.40 (^) 4.0 ร 10 โ A. rate = k [Br 2 ]^2 [NO] B. rate = k [Br 2 ] [NO]^2 C. rate = k [Br 2 ]^2 D. rate = k [NO]^2 2. Which step is the rate-determining step of a reaction? A. The step with the lowest activation energy B. The final step C. The step with the highest activation energy D. The first step 3. The rate information below was obtained for the following reaction at a constant temperature. 2NO 2 (g) + F 2 (g) โ 2NO 2 F(g) [NO 2 ] / mol dmโ3^ [F 2 ] / mol dmโ3^ Rate / mol dmโ3^ sโ 2.0 ร 10 โ3^ 1.0 ร 10 โ2^ 4.0 ร 10 โ 4.0 ร 10 โ3^ 1.0 ร 10 โ2^ 8.0 ร 10 โ 4.0 ร 10 โ3^ 2.0 ร 10 โ2^ 1.6 ร 10 โ What are the orders of the reaction with respect to NO 2 and F 2? A. NO 2 is first order and F 2 is second order B. NO 2 is second order and F 2 is first order C. NO 2 is first order and F 2 is first order D. NO 2 is second order and F 2 is second order
7. Sodium thiosulfate solution, Na 2 S 2 O 3 (aq), and hydrochloric acid, HCl(aq), react spontaneously to produce solid sulfur, S(s), according to the equation below. S 2 O 3 2โ(aq) + 2H+(aq) โ S(s) + SO 2 (aq) + H 2 O(l) A student experimentally determined the rate expression to be: rate = k [S 2 O 3 2โ(aq)]^2 Which graph is consistent with this information? 8. Consider the following reaction. NO 2 (g) + CO(g) โ NO(g) + CO 2 (g) At T < 227 ยฐC the rate expression is rate = k [NO 2 ]^2. Which of the following mechanisms is consistent with this rate expression? A. NO 2 + NO 2 N 2 O 4 fast N 2 O 4 + 2CO โ 2NO + 2CO 2 slow B. NO 2 + CO โ NO + CO 2 slow C. NO 2 โ NO + O slow CO + O โ CO 2 fast D. NO 2 + NO 2 โ NO 3 + NO slow NO 3 + CO โ NO 2 + CO 2 fast
9. Consider the following reaction. 2P + Q โ R + S This reaction occurs according to the following mechanism. P + Q โ X slow P + X โ R + S fast What is the rate expression? A. rate = k [P] C. rate = k [P][Q] B. rate = k [P][X] D. rate = k [P]^2 [Q] 10. What happens when the temperature of a reaction increases? A. The activation energy increases. C. The enthalpy change increases. B. The rate constant increases. D. The order of the reaction increases. 11. This question refers to the following reaction. X 2 + 2Y โ 2XY The reaction occurs in a series of steps. X 2 โ 2X slow X + Y โ XY fast What is the rate-determining step for this reaction mechanism? A. X 2 + 2Y โ 2XY C. X 2 โ 2X B. X 2 + Y โ XY + X D. X + Y โ XY 12. This question refers to the following reaction. X 2 + 2Y โ 2XY The reaction occurs in a series of steps. X 2 โ 2X slow X + Y โ XY fast What is the rate expression for this reaction? A. rate = k [XY] C. rate = k [X 2 ] B. rate = k [X 2 ][Y]^2 D. rate = k [2X]
16. Two species, P and Q, react together according to the following equation. P + Q โ R The accepted mechanism for this reaction is P + P P 2 fast P 2 + Q โ R + P slow What is the order with respect to P and Q? P Q A. (^1 ) B. 1 2 C. (^2 ) D. 2 2 17. The activation energy of a reaction may be determined by studying the effect of a particular variable on the reaction rate. Which variable must be changed? A. pH B. Concentration C. Surface area D. Temperature 18. What is the order of reaction with respect to NO 2 (g) and F 2 (g) given the following rate data at a certain tem- perature? [NO 2 (g)] / mol dm โ^3 [F 2 (g)] / mol dm โ^3 Rate / mol dmโ3^ minโ 0.1 0.2 0. 0.2 0.2 0. 0.1 0.4 0. Order with respect to NO 2 (g) Order with respect to F 2 (g) A. (^) first first B. (^) first second C. (^) second first D. (^) second second
