8. The table below describes two different reactions in which Reaction 1 is faster. What accounts for this observation? Reaction 1 Reaction 2.

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1 Public Review - Rates and Equilibrium June What does X represent in the diagram below? (A) activation energy for the forward reaction (B) activation energy for the reverse reaction (C) heat of reaction for the forward reaction (D) heat of reaction for the reverse reaction 2. Which increases the reaction rate? (A) decreasing the frequency of collisions (B) decreasing ªH for the reaction (C) increasing the frequency of collisions (D) increasing ªH for the reaction 3. Which observation best supports the Kinetic Molecular Theory? (A) Acetic acid odour is detected from across the room. (B) Liquid water freezes at 0 C under standard conditions. (C) Nitrogen dioxide gas is dark brown in colour. (D) When burned, butane produces more heat per mole than propane. 4. What is the high energy, unstable chemical species that exists in the transition from reactants to products? (A) activated complex (B) catalyst (C) inhibitor (D) reaction intermediate 5. What is the value of ªH for the forward reaction if its activation energy is 20.0 kj and the activation energy of the reverse reaction is 30.0 kj? (A) kj (B) kj (C) 10.0 kj (D) 50.0 kj 6. What affect would increasing the surface area of a solid reactant have on a system approaching equilibrium? (A) decreases the rate of the forward reaction (B) decreases the time to reach equilibrium (C) increases the equilibrium concentration of products (D) increases the equilibrium concentration of reactants 7. For the reaction mechanism below, increasing the concentration of which species would have the greatest effect on the overall reaction rate? X + Y 6 2 Z slow Z + 2 W 6 U fast Z + U 6 V fast (A) U (B) V (C) Y (D) Z 8. The table below describes two different reactions in which Reaction 1 is faster. What accounts for this observation? Reaction 1 Reaction 2 Reactants Fe 2+ (aq) + MnO 4 - (aq) MnO4 - (aq) + H 2 C 2 O 4 (aq) Temperature 20 o C 40 o C Concentration 0.5 mol/l solutions 1.0 mol/l solutions (AA) nature of reactants (BB) solution concentration (CC) surface area

2 (DD) temperature

3 9. The equilibrium system below is in a test tube at room temperature. When five drops of Fe(NO 3 )(aq) is added, a precipitate forms. H + (aq) + 2 CrO 2-4 (aq) º Cr 2 O 2-7 (aq) + OH - (aq) yellow orange 10. What happens to [O 2 (g)] and [H 2 O(g)] in the equilibrium below if the system is heated? 4 HCl (aq) + O 2(g) º 2 H 2 O (g) + 2 Cl 2(g) ªH = +113 kj 11. Given the equilibrium concentrations; [CO(g)] = mol/l, [H 2 (g)] = mol/l, and [CH 3 OH(g)] = mol/l, what is the value of K eq for the equilibrium below? CO (g) + 2 H 2 º CH 3 OH (g) (A) (B) (C) 2.51 (D) What happens to the equilibrium below when NO(g) is added to the system? 2 NO (g) + Cl 2(g) º 2 NOCl (g) 4% 51.(a) Use the table below to answer the following questions. Reaction Mechanism ªH Fe 3+ + H 2 O 2 FeOH 3+ + HO HO + H 2 O 2 6 H 2 O + HO 2 FeOH 3+ + HO 2 6 Fe 3+ + H 2 O + O kj kj kj i.) Write the equation for the overall net reaction. Identify reaction intermediate(s) and/or catalyst(s) present. Reaction Intermediate(s): Catalyst(s):

4 2% (b) The system below is at equilibrium. H 2 CO (g) º CO (g) + H 2(g) ªH = 5.36 kj What effect would increasing the temperature have on the value of K eq for this reaction? Justify your answer. 4% (c) Mixtures of hydrogen gas and carbon monoxide are placed in two separate flasks.one flask is at o C and the other is at o C. The graph below shows the change in methane concentration over time for each flask. 3 H 2(g) + CO (g) º CH 4(g) + H 2 O (g) ªH = -206 kj (xiii) Mark an X on each line in the graph, where equilibrium is first established. (ii) Which temperature condition, o C or o C, is represented by line A in the graph? Provide two reasons for your answer. 3% (d) The equilibrium below occurs when nitrogen monoxide is placed in a closed container and decomposes. 2 NO (g) º N 2(g) + O 2(g) When mol of NO(g) is placed in a sealed 1.0 L container at a particular temperature, 40.0% of it decomposes. Calculate the equilibrium constant at this temperature. June According to collision theory, which is true about reactants when a chemical reaction occurs? (A) They acquire the activation energy. (B) They are gases. (C) They are heated. (D) They have more PE than products. 2. Which letter below represents the heat of reaction? (A) A (B) B (C) C (D) D 3. Which best indicates the energy as reactants collide and form an activated complex? 4. Which factor explains why coal dust is explosive? (A) concentration (B) pressure (C) surface area

5 (D) temperature 5. Which reaction occurs fastest at room temperature? (A) 2 H 2 (g) + O 2 (g) 6 2 H 2 O(A) (B) 2 Ag + (aq) + CrO 4 2)(aq) 6 Ag 2 CrO 4 (s) (C) Pb(s) + 2 HCl(aq) 6 PbCl 2 (s) + H 2 (g) (D) CH 4 (g) + 2 O 2 (g) 6 CO 2 (g) + 2 H 2 O(g) 6. Which is the catalyst in the reaction mechanism below? Step 1: NO 2 (g) + SO 2 (g) 6 SO 3 (g) + NO(g) Step 2: NO(g) + ½O 2 (g) 6 NO 2 (g) (A) NO(g) (B) NO 2 (g) (C) O 2 (g) (D) SO 2 (g) 7. How many elementary steps are in the mechanism illustrated below? (A) 1 (B) 2 (C) 3 (D) 4 8. Which are necessary to establish a dynamic equilibrium? (A) a changing concentration and a closed system (B) a constant temperature and an open system (C) an irreversible reaction and an open system (D) a reversible reaction and a closed system (E) 9. The equilibrium below is established in a rigid 1.0 L container. CH 4 (g) + 2H 2 S(g) + heat º CS 2 (g) + 4H 2 (g) If some CH 4 (g) is added to the system, what happens to the concentration of CS 2 (g) and the value of K? 10. If [F 2 ] = mol/l and [F] = mol/l in the equilibrium below, what is the value of the equilibrium constant? F 2 (g) º 2 F(g) (A) G 6 (B) G 2 (C) G 2 (D) Which is the equilibrium expression for the system below? CaCO 3 (s) + 2 HF(g) CaF 2(s) + H 2 O(g) + CO 2 (g)

6 12. Which K value indicates a reaction in which products are most favoured? (A) (B) (C) (D) % 51. (a) Explain two ways that the rate of CO2(g) production can be increased in the reaction below. CaCO 3(s) + 2 HCl (aq) 6 CaCl 2(aq) + CO 2(g) + H 2 O (l) 2% (b) What is the equation for step 3 in the reaction mechanism below? Show workings. Step 1: 2 NO 6 N 2 O 2 Step 2: N 2 O 2 + H 2 6 N 2 O + H 2 O Step 3:? Overall reaction: 2 NO + 2 H2 ÿ N2 + 2 H2O Step 3: 2% (c) At 1000 K, sulfur dioxide is converted into sulfur trioxide, as shown below. 2 SO 2 (g) + O 2 (g) º 2 SO 3(g) K = 284 If [SO 2 ] = mol/l, [O 2 ] = mol/l, and [SO 3 ] = mol/l, is the mixture at equilibrium? Justify your answer. 4% (d) The equilibrium below was established under constant temperature conditions. Co(H 2 O) 2+ (aq) + 4 Cl-(aq) º CoCl 4 2- (aq) + 6H 2 O(l) pale pink deep blue (i) Explain what color change would occur if AgNO 3 was added to the system, producing a precipitate. (ii) When the equilibrium is placed in an ice bath it turns pale pink. Is ªH for the forward reaction positive or negative? Justify your answer. 2% (e) Explain what happens to the value of K in the equilibrium below when the temperature of the system is increased. N 2 (g) + 3 H 2 (g) 2 NHR 3 (g) + heat June In the potential energy diagram below, which represents the activation energy for the reverse reaction? (A) A (B) B (C) C (D) D 2. Which is true about an activated complex?

7 3. When studying the effect of temperature on the rate of the reaction below, what must be kept constant? HCl(aq) + NaHCO3(s) 6NaCl(aq) + H2O(l) + CO2(g) (A) concentration of HCl(aq) (B) concentration of NaCl(aq) (C) pressure of reaction vessel (D) volume of reaction vessel 4. What is produced in one step of a reaction mechanism and consumed in a later step? (A) activated complex (B) catalyst (C) inhibitor (D) intermediate 5. Which must occur for a chemical reaction to take place? (A) addition of a catalyst (B) addition of energy (C) collisions between reacting particles (D) formation of a reaction intermediate 6. In the graph below, what is the rate determining step? (A) A (B) B (C) C (D) D 7. What is true for the equilibrium below? Co(H2O)6 2+ (aq) + 4 Cl- (aq) + energy º CoCl 4 2- (aq) + 6 H2O (l) Pink Blue (A) Cooling the reaction flask will make the colour turn blue. (B) Cooling the reaction flask will make the colour turn pink. (C) Decreasing pressure will make the colour turn blue. (D) Decreasing pressure will make the colour turn pink. 8. At equilibrium, 2.2 mol of CH4(g), 2.2 mol of H2O(..), 0.12 mol of CO(g) and 0.36 mol of H2(g) are present in a 1.0 L container. What is the value of Keq for the equilibrium below? CH 4(g) + H 2 O (l) º CO (g) + 3 H 2(g) (A) (B) (C) (D) The graph below refers to an equilibrium. When does the system reach equilibrium? (A) A (B) B (C) C (D) D

8 10. Why is a chemical equilibrium described as dynamic? (A) Concentration of chemical species remains constant. (B) Minimum energy is achieved. (C) Reactants and products continue to form. (D) Temperature remains constant. 11. In the equilibrium system below, which change would decrease the concentration of O2(g)? N2 (g) + 2 O2 (g) + energy º N2O4 (g) (A) decrease the concentration of N2(g) (B) decrease the pressure of the reaction vessel (C) increase the temperature (D) increase the volume of the reaction vessel 12. In a 1.0 L container, 2.0 moles of CS2(g) and 4.0 moles of Cl2(g) are mixed to establish the equilibrium below. If 0.30 moles of CCl4(g) are present at equilibrium, how much Cl2(g) remains? CS2 (g) + 3 Cl2 (g) S2Cl2 (g) + CCl4 (g) (A) 0.30 mol (B) 0.90 mol (C) 3.1 mol (D) 3.9 mol 6% 51. (a) Use the table below to answer the following questions. (i) What is the enthalpy for the overall reaction? (ii) Identify the reaction intermediate(s) and/or catalyst(s) present. (iii) Sketch a clearly labelled potential energy diagram for this reaction mechanism. 3% (b) All Canadian automobiles are equipped with catalytic convertors to improve air quality. (i) Using the mechanism below for ozone production, describe how catalytic convertors decrease ground level ozone concentrations. (ii) Describe one way to improve the design of a catalytic convertor that will increase its ability to reduce air pollution. 4% (c) The system below is at equilibrium. (i) If the gases are in a sealed container, explain the effect increasing the volume would have on the equilibrium position. (ii) Explain what effect increasing the temperature of the reaction vessel would have on the value of Keq for this reaction.

9 June In the potential energy diagram below, which represents the activation energy for the catalysed reaction? (A) A (B) B (C) C (D) D 2. In a reaction E a (forward) is 28 kj and E a (reverse) is 54 kj. Which describes the forward reaction? 3. Marble chips and chalk dust are different forms of CaCO3(s). Which explains the difference in the reaction rate of each with vinegar? (A) concentration (B) pressure (C) surface area (D) temperature 4. Which refers to each single step in a reaction mechanism? (A) activated complex (B) elementary (C) intermediate (D) rate determining 5. Which substance, when added to the reaction mechanism below, will have the greatest effect on the overall reaction rate? (A) HOI (B) H2O (C) IG (D) OclG 6. Which predicts how an equilibrium responds to imposed changes? (A) Arrhenius definition (B) Faraday s law (C) Hess law (D) Le Châtelier s principle

10 7. Which change in the equilibrium below will result in the highest concentration of NO(g)? (A) adding a catalyst (B) increasing pressure (C) increasing temperature (D) removing oxygen 8. The reaction below is allowed to reach equilibrium. If O2(g) is added to the system, what is the effect on the value of [CO2(g)] and the value of K? 9. When the reaction below is at equilibrium, [Cl2] = mol/l, [N2] = mol/l, and [NCl3] = mol/l. What is the value of K? (A) (B) (C) (D) What is the equilibrium expression for the reaction below? 11. For the equilibrium below, the concentration of CO(g) and Cl2(g) are both mol/l. What is the equilibrium concentration of COCl2? (A) 0.24 (B) 0.84 (C) 1.2 (D) 4.2

11 12. A sample of ammonia is placed in a sealed vessel and allowed to reach equilibrium. Using the graph below, what is the value of K? (A) (B) 0.30 (C) 3.4 (D) (a) In a lab, data from two trials of the reaction below were collected. The graph illustrates the volume of oxygen produced over time for each trial. i) Which trial has the highest rate of O2 production? ii) On the diagram below, show how the graph for trial 2 will change if a catalyst is added after 6 seconds. iii) Give one factor, other than a catalyst, that could cause the different rates observed in the graph in part i), and explain how this factor affects the reaction rate.

12 51. (b) The mechanism below shows the decomposition of ozone in the upper atmosphere. i) What is the equation for the overall reaction? ii) Identify reaction intermediate(s) and/or catalyst(s) present. Reaction Intermediate(s): Catalyst(s): iii) Step 1 of the reaction mechanism does not occur unless ultraviolet radiationis present. Describe the role that ultraviolet radiation plays in the reaction. 51. (c) mol of H 2 O 2 (g) are placed in a 2.00 L flask at a certain temperature and allowed to establish the equilibrium below. If there are mol of O 2 (g) in the flask at equilibrium, what is K for the reaction? June Why does decreasing the concentration of a reactant usually decrease the rate of reaction? (A) causes more intense collisions (B) decreases the number of collisions per second (C) lowers the activation energy (D) provides an alternate reaction mechanism 2. Which graph represents the fastest exothermic reaction? (A) (B) (C) (D)

13 3. A student placed 3.0 g of Mg(s) into some HCl(aq) in two different experiments giving the reaction below. It took more time for all of the Mg(s) to react in the second experiment. Which accounts for the slower rate in the second experiment? Mg(s) + 2 HCl(aq) (A) a catalyst was added (B) [H 2 ] was decreased (C) Mg was crushed into a powder (D) temperature was decreased MgCl 2 (aq) + H 2 (g) 4. How does adding a catalyst to a reaction affect the reaction pathway and the activation energy? Reaction Pathway Provided Activation Energy (A) alternate higher (B) alternate lower (C) same higher (D) same lower 5. Which step of a reaction is the rate determining step? (A) fastest (B) first (C) last (D) slowest 6. What is the role of O 2 (g) in the mechanism below? Step 1: O 3 (g) + Br 2 (g) Br 2 O(g) + O 2 (g) Step 2: Br 2 (g) + O 2 (g) 2 BrO(g) Step 3: 2 BrO(g) Br 2 O 2 (g) (A) catalyst (B) intermediate (C) product (D) reactant 7. The diagram below illustrates the reverse reaction rate for the equilibrium shown. Which explains what happens at t 1? N 2 (g) + 3 H 2 (g) º 2 NH 3 (g) + energy (A) [NH 3 ] decreased (B) [NH 3 ] increased (C) pressure is increased (D) temperature is decreased 8. Which is necessary for equilibrium to occur? (A) closed system (B) open system (C) rate of the forward reaction is zero (D) rate of the reverse reaction is zero

14 9. Some Fe(NO 3 ) 3 (aq) and NaSCN(aq) are added to a sealed flask and allowed to reach equilibrium. What happens to the reverse reaction rate and [Fe 3+ ] as equilibrium is being reestablished? Fe 3+ (aq) + SCNG(aq) W FeSCN 2+ (aq) Reverse Rate [Fe 3+ ] (A) decreased decreased (B) decreased increased (C) increased decreased (D) increased increased 10. Which describes the temperature and pressure needed for the maximum yield of styrene? C 6 H 5 CH 2 CH 3 (g) kj W C 6 H 5 CHCH 2 (g) + styrene H 2 (g) Temperature Pressure (A) high high (B) high low (C) low high (D) low low 11. Which chemical equation corresponds to the equilibrium constant expression shown below? (A) 2A + 3B W C (B) A + B W C (C) C W A + B (D) C W 2A + 3B K = eq [ A] [ B] [ C] At equilibrium, [CCl 4 ] = 0.28 mol/l and [Cl 2 ] = mol/l. What is the value of K eq? (A) !4 (B) !2 (C) !1 (D) CCl 4 (g) W C(s) + 2 Cl 2 (g) 51.(a) The reaction below has an activation energy of 209 kj. Sketch a potential energy diagram for the reaction, and label the activation energy and heat of reaction. 2 NO 2 (g) + O 2 (g) kj 2 NO 3 (g) (b) For the reaction below, it takes longer to collect 35 ml of CO 2 (g) using acid at room temperature compared to acid at 60.0 EC. Explain why. CaCO 3 (s) + H 2 SO 4 (aq) CO 2 (g) + CaSO 4 (s) + H 2 O(l) (c) Using collision theory, explain why zinc metal reacts more rapidly in concentrated HCl(aq) than in dilute Hcl(aq).

15 (d) Inside a propane tank, the equilibrium below is created. When propane gas is released from the tank, explain why condensation forms on the outside of the tank. C 3 H 8 (l) + Energy º C 3 H 8 (g) (e) For the reaction below, the graph shows how A 2 (g) and B 2 (g) come to equilibrium with AB(g) at constant temperature in a 1.0 L flask. Calculate the equilibrium constant. A 2 (g) + B 2 (g) º 2 AB(g) (f) Calculate K eq if 1.0 mol of N 2 O 4 is initially placed into a 1.0 L vessel, and at equilibrium 0.75 mol of N 2 O 4 remains in the vessel. N 2 O 4 (g) º 2 NO 2 (g)