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Problem 41a
Indicate whether each of the following statements about the reaction quotient Q is true or false: (a) The expression for 𝑄𝑐 looks the same as the expression for 𝐾𝑐.
Problem 41b
Indicate whether each of the following statements about the reaction quotient Q is true or false: (b) If 𝑄𝑐 < 𝐾𝑐, the reaction needs to proceed to the right to reach equilibrium.
Problem 43
At 100°C, the equilibrium constant for the reaction COCl2(𝑔) ⇌ CO(𝑔) + Cl2(𝑔) has the value 𝐾𝑐 = 2.19×10−10. Are the following mixtures of COCl2, CO, and Cl2 at 100°C at equilibrium? If not, indicate the direction that the reaction must proceed to achieve equilibrium.
(a) [COCl2] = 2.00×10−3 M, [CO] = 3.3×10−6 M, [Cl2] = 6.62×10−6 M
(b) [COCl2] = 4.50×10−2 M, [CO] = 1.1×10−7 M, [Cl2] = 2.25×10−6 M
(c) [COCl2] = 0.0100 M, [CO] = [Cl2] = 1.48×10−6 M
- As shown in Table 15.2, Kp for the equilibrium N2(g) + 3 H2(g) ⇌ 2 NH3(g) is 4.51 * 10^-5 at 450 _x001F_C. For each of the mixtures listed here, indicate whether the mixture is at equilibrium at 450 _x001F_C. If it is not at equilibrium, indicate the direction (toward product or toward reactants) in which the mixture must shift to achieve equilibrium. (a) 98 atm NH3, 45 atm N2, 55 atm H2. (b) 57 atm NH3, 143 atm N2, no H2. (c) 13 atm NH3, 27 atm N2, 82 atm H2.
Problem 44
- At 100 _x001F_C, Kc = 0.078 for the reaction SO2Cl2(g) ⇌ SO2(g) + Cl2(g). In an equilibrium mixture of the three gases, the concentrations of SO2Cl2 and SO2 are 0.108 M and 0.052 M, respectively. What is the partial pressure of Cl2 in the equilibrium mixture?
Problem 45
Problem 46
At 900 K, the following reaction has 𝐾𝑝 = 0.345: 2 SO2(𝑔) + O2(𝑔) ⇌ 2 SO3(𝑔) In an equilibrium mixture the partial pressures of SO2 and O2 are 0.135 atm and 0.455 atm, respectively. What is the equilibrium partial pressure of SO3 in the mixture?
- At 1285 _x001F_C, the equilibrium constant for the reaction Br2(g) ⇌ 2 Br(g) is Kc = 1.04 * 10^-3. A 0.200-L vessel containing an equilibrium mixture of the gases has 0.245 g of Br2(g) in it. What is the mass of Br(g) in the vessel?
Problem 47
- For the reaction H2(g) + I2(g) ⇌ 2 HI(g), Kc = 55.3 at 700 K. In a 2.00-L flask containing an equilibrium mixture of the three gases, there are 0.056 g H2 and 4.36 g I2. What is the mass of HI in the flask?
Problem 48
- At 800 K, the equilibrium constant for the reaction I2(g) ⇌ 2 I(g) is Kc = 3.1 * 10^-5. If an equilibrium mixture in a 10.0-L vessel contains 2.67 * 10^-2 g of I(g), how many grams of I2 are in the mixture?
Problem 49
Problem 51a
At 218°C, 𝐾𝑐 = 1.2×10−4 for the equilibrium NH4SH(𝑠) ⇌ NH3(𝑔) + H2S(𝑔) (a) Calculate the equilibrium concentrations of NH3 and H2S if a sample of solid NH4SH is placed in a closed vessel at 218°C and decomposes until equilibrium is reached.
Problem 52a
At 80°C, 𝐾𝑐 = 1.87×10−3 for the reaction PH3BCl3(𝑠) ⇌ PH3(𝑔) + BCl3(𝑔) (a) Calculate the equilibrium concentrations of PH3 and BCl3 if a solid sample of PH3BCl3 is placed in a closed vessel at 80°C and decomposes until equilibrium is reached.
Problem 52b
At 80°C, 𝐾𝑐 = 1.87×10−3 for the reaction PH3BCl3(𝑠) ⇌ PH3(𝑔) + BCl3(𝑔) (a) Calculate the equilibrium concentrations of PH3 and BCl3 if a solid sample of PH3BCl3 is placed in a closed vessel at 80°C and decomposes until equilibrium is reached. (b) If the flask has a volume of 0.250 L, what is the minimum mass of PH3BCl3(𝑠) that must be added to the flask to achieve equilibrium?
Problem 53
At 25°C, the reaction CaCrO4(𝑠) ⇌ Ca2+(𝑎𝑞) + CrO42−(𝑎𝑞) has an equilibrium constant 𝐾𝑐 = 7.1×10−4. What are the equilibrium concentrations of Ca2+ and CrO42− in a saturated solution of CaCrO4?
- Consider the reaction \( \text{CaSO}_4(\text{s}) \rightleftharpoons \text{Ca}^{2+}(\text{aq}) + \text{SO}_4^{2-}(\text{aq}) \) At 25 °C, the equilibrium constant is \( K_c = 2.4 \times 10^{-5} \) for this reaction. (a) If excess \( \text{CaSO}_4(\text{s}) \) is mixed with water at 25 °C to produce a saturated solution of \( \text{CaSO}_4 \), what are the equilibrium concentrations of \( \text{Ca}^{2+} \) and \( \text{SO}_4^{2-} \)? (b) If the resulting solution has a volume of 1.4 L, what is the minimum mass of \( \text{CaSO}_4(\text{s}) \) needed to achieve equilibrium?
Problem 54
Problem 55
At 2000°C, the equilibrium constant for the reaction 2 NO(𝑔) ⇌ N2(𝑔) + O2(𝑔) is 𝐾𝑐 = 2.4×103. If the initial concentration of NO is 0.175 M, what are the equilibrium concentrations of NO, N2, and O2?
- For the reaction I2(g) + Br2(g) ⇌ 2 IBr(g), Kc = 280 at 150 _x001F_C. Suppose that 0.500 mol IBr in a 2.00-L flask is allowed to reach equilibrium at 150 _x001F_C. What are the equilibrium concentrations of IBr, I2, and Br2?
Problem 56
Problem 57
For the equilibrium Br2(𝑔) + Cl2(𝑔) ⇌ 2 BrCl(𝑔) at 400 K, 𝐾𝑐 = 7.0. If 0.25 mol of Br2 and 0.55 mol of Cl2 are introduced into a 3.0-L container at 400 K, what will be the equilibrium concentrations of Br2, Cl2, and BrCl?
Problem 58
At 373 K, 𝐾𝑝 = 0.416 for the equilibrium 2 NOBr(𝑔) ⇌ 2 NO(𝑔) + Br2(𝑔) If the equilibrium partial pressures of NOBr(𝑔) and Br2(𝑔) are both 0.100 atm at 373 K, what is the equilibrium partial pressure of NO(𝑔)?
- Methane, CH4, reacts with I2 according to the reaction CH4(g) + I2(g) ⇌ CH3I(g) + HI(g). At 630 K, Kp for this reaction is 2.26 × 10^-4. A reaction was set up at 630 K with initial partial pressures of methane at 105.1 torr and I2 at 7.96 torr. Calculate the pressures, in torr, of all reactants and products at equilibrium.
Problem 59
Problem 61e
Consider the following equilibrium, for which Δ𝐻<0
2 SO2(𝑔) + O2(𝑔) ⇌ 2 SO3(𝑔)
(e) the total pressure of the system is increased by adding a noble gas
Problem 61f
Consider the following equilibrium, for which Δ𝐻<0
2 SO2(𝑔) + O2(𝑔) ⇌ 2 SO3(𝑔)
(f) How will each of the following changes affect an equilibrium mixture of the three gases: SO3(𝑔) is removed from the system?
Problem 62a,b,c
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (a) increase [NH3] (b) increase [H2O] (c) decrease [O2]
Problem 62d
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (d) decrease the volume of the container in which the reaction occurs
Problem 62e
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (e) add a catalyst
Problem 62f
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (f) increase temperature.
- How do the following changes affect the value of the equilibrium constant for a gas-phase exothermic reaction: (a) removal of a reactant, (b) removal of a product?
Problem 63
- For a certain gas-phase reaction, the fraction of products in an equilibrium mixture is increased by either increasing the temperature or by increasing the volume of the reaction vessel. Does the balanced chemical equation have more molecules on the reactant side or product side?
Problem 64
Problem 65a
Consider the following equilibrium between oxides of nitrogen 3 NO(g) ⇌ NO2(g) + N2O(g) (a) At constant temperature, would a change in the volume of the container affect the fraction of products in the equilibrium mixture?
Problem 66a
Methanol (CH3OH) can be made by the reaction of CO with H2: CO(𝑔) + 2 H2(𝑔) ⇌ CH3OH(𝑔) (a) Use thermochemical data in Appendix C to calculate ΔH° for this reaction.
Problem 66b
Methanol (CH3OH) can be made by the reaction of CO with H2: CO(𝑔) + 2 H2(𝑔) ⇌ CH3OH(𝑔) (b) To maximize the equilibrium yield of methanol, would you use a high or low temperature?