Disturbing a System at Equilibrium Calculations To help with the calculations we must determine the direction that the equilibrium will shift by comparing Q with Kc We can then use the calculated Kc to calculate the new equilibrium concentrations that result from adding or removing one or more species from the eq Calculate new eq concentrations that result from decreasing or increasing the volume of a gaseous system 1 An equilibrium mixture from the following reaction was found to contain 0 20 mol L of A 0 30 mol L of B and 0 30 mol L of C What is the value of Kc for this reaction A B C g g g 2 If the volume of the reaction vessel were suddenly halved while the temperature remained constant what would be the new equilibrium concentrations First what are the now initial concentrations of all the reactants 1 Calculate Q after the volume has been halved 3 Solve the quadratic equation for this expression 1 65 1 65 2 4 1 0 18 x 2 1 1 65 1 42 x 1 5 and 0 12 2 Because the limits are 0 x 0 60 we can discard 1 5 as an answer Thus 0 12 is the only possible answer A 0 40 x M 0 52 M B C 0 60 x M 0 48 M 4 If the initial volume of the reaction vessel were doubled while the temperature remains constant what will the new equilibrium concentrations be Recall that the original concentrations were A 0 20 M B 0 30 M and C 0 30 M What was Kc What are the new initial conc What is Q Which way does eq have to shift to reach Kc A g B g C g 5 2 Use algebra to represent the new concentrations A B C g New initial s 0 10 M g 0 15 M g 0 15 M 6 A 2 00 liter vessel in which the following system is in equilibrium contains 1 20 moles of COCl2 0 60 moles of CO and 0 20 mole of Cl2 Calculate Kc COCl CO g Cl 2 g 2 g 7 An additional 0 80 mole of Cl2 is added to the vessel at the same temperature Calculate the molar concentrations of CO Cl2 and COCl2 when the new equilibrium is established COCl CO g Cl 2 g 2 g 8 Applying Equilibrium Concepts The HaberBosch Ammonia Process The Haber process is used for the commercial production of ammonia NH3 made from atmospheric N2 NH3 used to make plastics explosives synthetic fibers This is an enormous industrial process in the US and many other countries Ammonia is the starting material for fertilizer production 9 N 2 g 3 H 2 g Fe metal oxides 2 NH3 g H o 92 22 kJ N 2 g is obtained from liquid air H 2 g obtained from coal gas This reaction is run at a T 450o C and P of N 2 200 to 1000 atm G 0 which is favorable H 0 also favorable S 0 which is unfavorabl e However th e reaction kinetics are very slow at low temperatu res Haber s solution t o this dilemma 10 Haber s solution t o this dilemma 1 Increase T to increase rate but yield is decreased 2 Increase reaction pressure to right 3 Use excess N 2 to right 4 Remove NH3 periodical ly to right The reaction system never reaches equilibriu m because NH3 is removed This increases the reaction yield and helps with the kinetics 11 This diagram illustrates the commercial system devised for the Haber Bosch process 12