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Problem 1a
(a) Based on the following energy profile, predict whether kf > kr or kf < kr. [Section 15.1]
Problem 2
The following diagrams represent a hypothetical reaction A Β‘ B, with A represented by red spheres and B represented by blue spheres. The sequence from left to right represents the system as time passes. Does the system reach equilibrium? If so, in which diagram(s) is the system in equilibrium? [Sections 15.1 and 15.2]
- Consider the equilibrium Na2O(s) + SO2(g) β Na2SO3(s). (a) Write the equilibrium-constant expression for this reaction in terms of partial pressures. (b) All the compounds in this reaction are soluble in water. Rewrite the equilibrium-constant expression in terms of molarities for the aqueous reaction.
Problem 3
Problem 4d
The following diagram represents a reaction shown going to completion. Each molecule in the diagram represents 0.1 mol, and the volume of the box is 1.0 L. (d) Assuming that all of the molecules are in the gas phase, calculate n, the change in the number of gas molecules that accompanies the reaction. [Section 15.2]
Problem 6
Ethene (C2H4) reacts with halogens (X2) by the following reaction:
C2H4(π) + X2(π) β C2H4X2(π)
The following figures represent the concentrations at equilibrium at the same temperature when X2 is Cl2 (green), Br2 (brown), and I2 (purple). List the equilibria from smallest to largest equilibrium constant. [Section 15.3]
Problem 8a
When lead(IV) oxide is heated above 300Β°C, it decomposes according to the reaction, 2 PbO2(π ) β 2PbO(π ) + O2(π). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400Β°C and allowed to come to equilibrium, which of the following statements is or are true? a. There will be less PbO2 remaining in vessel A than in vessel B.
Problem 8b
When lead(IV) oxide is heated above 300Β°C, it decomposes according to the reaction, 2 PbO2(π )β2PbO(π )+O2(π). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400Β°C and allowed to come to equilibrium, which of the following statements is or are true?
b. The solid left at the bottom of each vessel will be a mixture of PbO2(π ) and PbO(π ).
Problem 8c
When lead(IV) oxide is heated above 300Β°C, it decomposes according to the reaction, 2 PbO2(π )β2PbO(π )+O2(π). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400Β°C and allowed to come to equilibrium, which of the following statements is or are true? c. The partial pressure of O2(π) will be the same in vessels A and B. [Section 15.4]
Problem 9a
The reaction A2 + B2 β 2 AB has an equilibrium constant Kc = 1.5. The following diagrams represent reaction mixtures containing A2 molecules (red), B2 molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?
Problem 10a
The diagram shown here represents the equilibrium state for the reaction A2(π) + 2B(π) β 2AB(π). (a) Assuming the volume is 2 L, calculate the equilibrium constant πΎπ for the reaction.
Problem 13
Suppose that the gas-phase reactions A β B and B β A are both elementary reactions with rate constants of 4.7Γ10β3β sβ1 and 5.8Γ10β1 sβ1, respectively. (a) What is the value of the equilibrium constant for the equilibrium A(g) β B(g)? (b) Which is greater at equilibrium, the partial pressure of A or the partial pressure of B?
Problem 14a
The equilibrium constant for the dissociation of molecular iodine, I2(g) β 2 I(g), at 800 K is Kc = 3.1 Γ 10β5. (a) Which species predominates at equilibrium I2 or I?
Problem 14b
The equilibrium constant for the dissociation of molecular iodine, I2(g) β 2 I(g), at 800 K is Kc = 3.1Γ10β5. (b) Assuming both forward and reverse reactions are elementary reactions, which reaction has the larger rate constant, the forward or the reverse reaction?
Problem 15e
Write the expression for Kc for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.
(a) 3 NO(g) β N2O(g) + NO2(g)
(b) CH4(g) + 2 H2S(g) β CS2(g) + 4 H2(g)
(c) Ni(CO)4(g) β Ni(s) + 4 CO(g)
(d) HF(aq) β H+(aq) + F-(aq)
(e) 2Ag(s) + Zn2+(aq) β 2 Ag+(aq) + Zn(s)
(f) H2O(l) β H+(aq) + OH-(aq)
(g) 2 H2O(l) β 2 H+(aq) + 2 OH-(aq)
Problem 16a,c,d,e,f,g
Write the expressions for Kc for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.
(a) 2 O3(g) β 3 O2(g)
(c) 2 C2H4(g) + 2 H2O(g) β 2 C2H6(g) + O2(g)
(d) C(s) + 2 H2(g) β CH4(g)
(e) 4 HCl(aq) + O2(g) β 2 H2O(l) + 2 Cl2(g)
(f) 2 C8H18(l) + 25 O2(g) β 16 CO2(g) + 18 H2O(g)
(g) 2 C8H18(l) + 25 O2(g) β 16 CO2(g) + 18 H2O(l)
Problem 16b
Write the expressions for πΎπ for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.
(b) Ti(π ) + 2Cl2(π) β TiCl4(π)
- When the following reactions come to equilibrium, does the equilibrium mixture contain mostly reactants or mostly products? (a) N2(g) + O2(g) β 2 NO(g), Kc = 1.5 Γ 10^-10 (b) 2 SO2(g) + O2(g) β 2 SO3(g), Kp = 2.5 Γ 10^9
Problem 17
Problem 18
Which of the following reactions lies to the right, favoring the formation of products, and which lies to the left, favoring the formation of reactants?
(a) 2 NO(g) + O2(g) β 2 NO2(g) Kp = 5.0 Γ 1012
(b) 2 HBr(g) β H2(g) + Br2(g) Kc = 5.8Γ10β18
Problem 19a,b
Which of the following statements are true and which are false? (a) The equilibrium constant can never be a negative number. (b) In reactions that we draw with a single-headed arrow, the equilibrium constant has a value that is very close to zero.
Problem 19c
Which of the following statements are true and which are false? (c) As the value of the equilibrium constant increases, the speed at which a reaction reaches equilibrium must increase.
Problem 21
If πΎπ = 0.042 for PCl3(π) + Cl2(π) β PCl5(π) at 500 K, what is the value of πΎπ for this reaction at this temperature?
- Calculate Kc at 303 K for SO2(g) + Cl2(g) β SO2Cl2(g) if Kp = 34.5 at this temperature.
Problem 22
- The equilibrium constant for the reaction 2 NO(g) + Br2(g) β 2 NOBr(g) is Kc = 1.3 * 10^-2 at 1000 K. (b) Calculate Kc for 2 NOBr(g) β 2 NO(g) + Br2(g). (c) Calculate Kc for NOBr(g) β NO(g) + 1/2 Br2(g).
Problem 23
Problem 24b
Consider the following equilibrium: 2 H2(g) + S2(g) β 2 H2S(g) Kc = 1.08 Γ 107 at 700Β°C (b) Does the equilibrium mixture contain mostly H2 and S2 or mostly H2S?
Problem 24c
Consider the following equilibrium: 2 H2(g) + S2(g) β 2 H2S(g) Kc = 1.08 Γ 107 at 700Β°C (c) Calculate the value of πΎπ if you rewrote the equation H2(g) + 1/2 S2(g) β H2S(g)
Problem 25a,b
At 1000 K, πΎπ = 1.85 for the reaction SO2(π) + 1/2 O2(π) β SO3(π) (a) What is the value of Kp for the reaction SO3(π) β SO2(π) + 1/2 O2(π)? (b) What is the value of Kp for the reaction 2 SO2(π) + O2(π) β 2 SO3(π)?
Problem 25c
At 1000 K, πΎπ = 1.85 for the reaction SO2(π) + 12 O2(π) β SO3(π) (c) What is the value of πΎπ for the reaction in part (b)?
Problem 26a
Consider the following equilibrium, for which at πΎπ = 0.0752 at 480Β°C: 2 Cl2(π) + 2 H2O(π) β 4 HCl(π) + O2(π) (a) What is the value of πΎπ for the reaction 4 HCl(π) + O2(π) β 2 Cl2(π) + 2 H2O(π)?
Problem 27
The following equilibria were attained at 823 K:
CoO(s) + H2(g) β Co(s) + H2O(g) Kc = 67
CoO(s) + CO(g) β Co(s) + CO2(g) Kc = 490
Based on these equilibria, calculate the value of πΎπ for H2(π)ββ+ CO2(π) β CO(π) + H2O(π) at 823 K.
Problem 28
Consider the equilibrium N2(π) + O2(π) + Br2(π) β 2 NOBr(π) Calculate the equilibrium constant πΎπ for this reaction, given the following information at 298 K:
2 NO(π) + Br2(π) β 2 NOBr(π) πΎπ = 2.02
NO(π) β N2(π) + O2(π) πΎπ = 2.1Γ1030