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Equilibrium – Chapter 15

Equilibrium – Chapter 15. Equilibrium is achieved when forward and reverse reaction rates are equal. aA + bB ↔ cC + dD. Watch this animation http://www.youtube.com/watch?v=LMIbJ-B92Ho. [X] = concentration of species X in molarity P x = pressure of gas X in atmospheres.

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Equilibrium – Chapter 15

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  1. Equilibrium – Chapter 15

  2. Equilibrium is achieved when forward and reverse reaction rates are equal. aA + bB ↔ cC + dD Watch this animation http://www.youtube.com/watch?v=LMIbJ-B92Ho [X] = concentration of species X in molarity Px= pressure of gas X in atmospheres

  3. ex Write the equilibrium constant for the following reaction: 2NO(g) + Cl2(g) ↔ 2NOCl(g)

  4. ex The reaction of N2 with O2 to form NO might be considered a means of "fixing" nitrogen: N2(g) + O2(g) ↔ 2NO(g) Determine the K for: 2NO ↔ N2 + O2

  5. for 4NO ↔ 2N2 + 2O2

  6. Kp is the equilibrium expression in terms of pressure for a reaction involving only gases. It is not necessarily equal to Kc. Kp = Kc(RT)Δn Δn = sum of the coefficients of the gas products - sum of the coefficients of the gas reactants. ex SnO2(s) + 2CO(g) ↔ Sn(s) + 2CO2(g)

  7. Applications of K K >> 1 equilibrium lies to the right, products favored K << 1 equilibrium lies to the left, reactants favored Important: The size of K and the time to reach equilibrium are NOT related.

  8. Link to simulation http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/kim2s2_5.swf

  9. Prediction of the direction of a reaction Reaction quotient, Q, takes the same form as K but is the expression at a given time, not necessarily at equilibrium. Q > K ← Q = K equilibrium Q < K →

  10. Ex - At 448oC the equilibrium constant for the following reaction, Kc, is 50.5. H2(g) + I2(g) ↔ 2HI Predict the direction in which the reaction will proceed to reach equilibrium at 448oC if we start with 0.020 mol of HI, 0.010 mol of H2 and 0.030 mol of I2 in a 2.0 L container.

  11. Calculation of Equilibrium Concentrations ex For the Haber process, N2(g) + 3H2(g) ↔ 2NH3(g) Kp = 1.45x10-5 at 500oC. In an equilibrium mixture of the three gases at 500oC, the partial pressure of H2 is 0.928 atm and that of N2 is 0.432 atm. What is the partial pressure of NH3 in the equilibrium mixture?

  12. ex A 1.000 L flask is filled with 1.000 mol of H2 and 2.000 mol of I2 at 448oC. The value of Kc at this temperature is 50.5. What are the equilibrium concentrations of H2, I2, and HI?

  13. Here is the quiz https://docs.google.com/spreadsheet/embeddedform?formkey=dDM4ODY2LWJKVGdXM2dnQXdkTjBrbUE6MQ

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