Chapter 13: Chemical Equilibrium (CHEM 2B) 13.1 A chemical engineer injects limestone (CaCO3) into the hot flue gas of a coalburning power plant to form lime (CaO), which scrubs SO2 from the gas and forms gypsum (CaSO4.2H2O) Find Kc for the following reaction, if CO2 pressure is in atmospheres: 13.2 For the reaction N2O4(g) < -> 2NO2(g), Kc = 0.21 at 100°C At a point during the reaction, [N2O4] = M and [NO2} = If not, in which direction is it progressing? 13.3 In a study of the conversion of methane to other fuels, a chemical engineer mixes gaseous CH4 and H2O in a 0.32-L flask at 1200 K At equilibrium, the flask contains 0.26 mol of CO, 0.091 mol of H2, and 0.041 mol of CH4 What is [H2O] at equilibrium? Kc = 0.26 for the equation CH4(g) + H2O (g) < - > CO(g) + 3H2(g) 13.4 Fuel engineers use the extent of the change from CO and H2O to CO2 and H2 to regulate the proportions of synthetic fuel mixtures If 0.250 mol of CO and 0.250 mol of H2O are placed in a 125 -mL flask at 900 K, what is the composition of the equilibrium mixture? At this temperature, Kc is 1.56 for the equation: CO(g) + H2O (g) < - > CO2(g) + H2(g) 13.5 Phosgene is a potent chemical warfare agent that is now outlawed by international agreement It decomposes by the reaction Calculate [CO], [CI2], and [COCI2] when each of the following amounts of phosgene decomposes and reaches equilibrium in a 1O.0-L flask: (a) 5.00 mol of COCl2 (b) 100 mol of COCl2 Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU 19 - Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam Email: nguyentienthao@gmail.com 13.6 The research and development unit of a chemical company is studying the reaction of CH4 and H2S, two components of natural gas: CH4(g) + 2H2S(g) < - > CS2(g) + 4H2(g) 2.00 mol of H2S, and In one experiment, 1.00 mol of CH4, 1.00 mol of CS2, 2.00 mol of H2 are mixed in a 250-mL vessel at 960°C At this temperature, Kc = 0.036 (a) In which direction will the reaction proceed to reach equilibrium? (b) If [CH4] =5.56 M at equilibrium, what are the equilibrium concentrations of the other substances? 13.7 To improve air quality and obtain an useful product, chemists often remove sulfur from coal and natural gas by treating the fuel contaminant hydrogen sulfide with O2: 2H2S(g) + O2 (g) < - > 2S(g) + 2H2O(g) What happens to (a) [H2O] if O2 is added? (b) [H2S] if O2 is added? (c) [O2] if H2S is removed? (d) [H2S] if sulfur is added? 12.8 How would you change the volume of each of the following reactions to increase the yield of the products? 12.9 How does an increase in temperature affect the equilibrium concentration of the underlined substance and Kc for each of the following reactions? 13.10 For the reaction of nitrogen with hydrogen to produce ammonia: N2(g) + 3H2 (g) < - > 2NH3(g) Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU 19 - Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam Email: nguyentienthao@gmail.com the equilibrium concentrations of N2, H2, and NH3 are 0.15, 0.80, and 0.20 mol/L respectively at 400°C What is the value of Kc? 13.11 For the same reaction in Problem 13.10 but at a different temperature, if one starts with 0.1 mol/L of both hydrogen and nitrogen, the equilibrium concentration of ammonia is 0.040 mol/L Calculate Kc· 10.12 When gasoline burns in an automobile, the temperature is high enough that nitric oxide forms from the elements nitrogen and oxygen : N2(g) + O2 (g) < - > 2NO(g) At 2000°C, Kc for this reaction is 0.10 What are the equilibrium concentrations of NO, N2 and O2, when the starting concentration of each reactant is 1.0 mol/l? 13.13 At a certain temperature, Kc for the reaction (in Problem13.12) between N2 and O2 to form NO is 3.2 x1 0-4 What is the equilibrium concentration of NO when 0.150 moles of N2 and 0.30 moles of O2 are added to a 1.50 l container? 13.14 For the Haber process in which nitrogen is converted to ammonia N2(g) + 3H2 (g) < - > 2NH3(g) H = -92.0 kJ If thee quilibrium constant at room temperature is 5.0 x108 At 200°C, will K2 be smaller or larger than K1 ? Additional problems: Chapter 13: 19, 21, 23, 33, 37, 41, 47, 49, 51,53, 57, 59, 65, 67, 69 Deadline: 08/22/2011 Nguyen Tien Thao, Faculty of Chemistry, Hanoi College of Science, VNU 19 - Le Thanh Tong, Hoan Kiem, Hanoi, Vietnam Email: nguyentienthao@gmail.com