Chapter 14 Lecture Problems


Introduction to Equlibrium

M&M's Spreadsheet

Heterogenous Equlibrium

  1. For the reaction CaCO3(s) (limestone) <-> CaO(s) (lime) + CO2(g)
  2. At 1173 K, Kp = 1.04 atm
  3. Start with 250 g of CaCO3(s) and a 20 liter container
  4. Start with 250 g of CaCO3(s) and a 400 liter container
  5. Solutions


Ammonia Equlibrium

For the reaction N2 (g) + 3 H2 (g) <--> 2 NH3 (g)
  1. Calculate Kc
    1. N2 = 0.921 M
    2. H2 = 0.763 M
    3. NH3 = 0.157 M

  2. Calculate Q if:
  3. N2H2NH3
    1.8310.7630.157
    10.3210.7630.157
    0.9210.03630.157
    0.02590.02770.0102

  4. Solutions


Kp and Kc

  1. Determining Kp, given Kc = 0.06025 liter2 mole-2 for the reaction

    N2(g) + 3 H2(g) <-> 2 NH3(g)

  2. Solve for the equlibrium pressure of NH3, given equlibrium conditions at 25 °C where PN2 = 12 atm and PH2 = 35 atm for the reaction:

    N2(g) + 3 H2(g) <-> 2 NH3(g)

  3. Solutions


PCl3

  1. Given INITIAL NON-EQULIBRIUM conditions, calculate the final EQULIBIRUM conditions. In solving this type of reaction the quadratic equation is often required. The example below shows one way to work this type of problem. For the following BALANCED reaction:

    PCl3 (g) + Cl2 (g) <-> PCl5 (g)
    At 230 C, Kc = 49 liter mole-1

    Initial conditions
    mass PCl3 = 50 gm
    mass Cl2 = 50 gm
    mass PCl5 = 0 gm
    volume = 5 liter
  2. Solutions


NO Equlibrium

Calculate the equlibrium pressure of NO at 300, 600, and 1500 K. For the reaction:

N2 + O2 <-> 2 NO

  1. Given starting pressures (typical atmospheric concentrations) of:
    1. PN2 = 0.80 atm
    2. PO2 = 0.20 atm
    3. P NO = 0.00 atm
  2. And equlibrium constants
    1. K = 10-30.5 at 300 K
    2. K = 10-14.6 at 600 K
    3. K = 10-5.1 at 1500 K
  3. solutions

HOCl Equlibrium

For the system: H2O (g) + Cl2O (g) <-> 2 HOCl (g)
  1. Given the equlibrium partial pressures solve for Kp
    1. PH2O = 200.0 torr
    2. PCl2O = 48.7 torr
    3. PHOCl = 29.6 torr

  2. Given equlibrium partial pressures of reactants, find product
    1. PH2O = 23.4 torr
    2. PCl2O = 123.5 torr

  3. Given initial (non-equlibrium) pressures, find equlibrium conditions
    1. PH2O = 100.0 torr
    2. PCl2O = 50.0 torr
    3. PHOCl = 0.0 torr

  4. Solutions

Acid Base Equlibrium

  1. At equlibrium
    1. [NH3] = 0.897 M
    2. [NH4+ = 0.345 M

  2. Equlibrium Constants
    1. Ka = 5.6 x 10-10
    2. Kw = 1.0 x 10-14
    3. Kb = ?

  3. Find the equlibrium concentrations of:
    1. H3O+
    2. OH-

  4. Solutions

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