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K eq for GASES

K eq for GASES. Kp. Equilibrium and Pressure. 2SO 2 (g) + O 2 (g) 2SO 3 (g) If reactants and products are gases, partial pressures of each species can be used to determine the equilibrium The total pressure = P SO 2 + P O 2 + P SO 3. Concentration of Gases.

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K eq for GASES

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  1. Keq for GASES Kp

  2. Equilibrium and Pressure 2SO2(g) + O2(g) 2SO3(g) • If reactants and products are gases, partial pressures of each species can be used to determine the equilibrium • The total pressure = PSO2 + PO2+ PSO3

  3. Concentration of Gases For reactions that contain gases: PV = nRT P = (n/V)RT P = CRT “C” is concentration in mol/L C = P/RT • The concentration of a gas is directly proportional to the pressure exerted by the gas.

  4. Problems Involving Pressure 2 NO2 (g) N2O4 (g) KP = 7.63atm at 300K. What are the equilibrium pressures of NO2 and N2O4 if a flask initially contains 1.000 atm of NO2? What is the value of the Kc at 300K.

  5. Relating Kp and Kc Kp = Kc (RT)Δn Kp = partial pressure constant using atm Kc = molar concentration constant using M R = ideal gas constant, 0.0821 L-atm/mol-K T = absolute temperature in K Δn= moles of product – moles of reactants

  6. DIFFERENT TYPE OF K

  7. Ksp - Solubility Product of a Salt KCl (s) K+ (aq) + Cl- (aq) CaCl2 (s) Ca+2 (aq) + 2 Cl- (aq)

  8. Ksp values Is any substance truly insoluble? Why are some substances more soluble than others?

  9. Problem Involving Ksp The Ksp of lead (II) chloride at 298K is 1.7 x 10-5. • Write the dissociation of lead (II) chloride in water. • Write the expression for the solubility product, Ksp, of lead (II) chloride. • Determine the concentration of the chloride ions and the lead ions of a saturated solution at 298K.

  10. Kw - Autoionization of Water Kw is 1.00 x 10-14 at room temperature. What would be the Keq expression? • How does the [H3O+] compare to the [OH-]? • What would be the [H3O+]? • What would be the pH? Like any other equilibrium constant, the value of Kw varies with temperature.

  11. Ka – Acid Dissociation Constant Arrhenius acids dissociate to produce hydrogen ions in solution. What is the difference between a strong and weak acid?

  12. Ka values

  13. Problem Involving Ka Acetic acid, HC2H3O2, has a Ka of 1.7 x 10-5 at 298K. • Write the expression for the acid dissociation of acetic acid. • Determine the concentration of the hydrogen ions and the acetate ions at 298K of a 1.0 M acetic acid.

  14. Kb – Base Dissociation Constant Arrhenius bases dissociate to produce hydroxide ions in solution. Some bases dissociate completely; other dissociate only partially. This determines if a base is strong or weak.

  15. Kb values

  16. Problem Involving Kb 1.0 moles of pure ammonia gas is dissolved to make a 1 Liter solution at 298K. Ammonia partially dissociates to produce the ions shown below. Ammonia, NH3, has a Kb of 1.8 x 10-5 at 298K. • Write the expression for the Kb of ammonia. • What is the hydroxide concentration at equilibrium? • What is the pH of a 1.0 M NH3(aq) solution?

  17. DIFFERENT TYPE OF K MULTISTEP REACTIONS

  18. Overall Keq A + B C Keq = K1 C  D + E Keq = K2 A + B D + E Keq = K1K2

  19. Practice Problem Mg(OH)2 (s) Mg+2(aq) + 2 OH- (aq) Ksp = 5.6 x 10-11 MgF2 (s) Mg+2(aq) + 2 F- (aq) Ksp = 5.8 x 10-10 NET REACTION: 2 F- (aq) + Mg(OH)2 (s) 2 OH- (aq) + MgF2 (s) Manipulate the equations for the dissolving of Mg(OH)2 and MgF2 to obtain the net ionic reaction. Calculate the Keq of the net ionic reaction.

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