Card Set Information

2011-09-30 09:12:30

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  1. Equilibrium constant expression for aA + bB ↔ cC + dD
    • K = K1/K-1 = [C]c[D]d/[A]a[B]b
    • Product favored: K has large value
    • Reactant favoried: K has a small value
    • Note - Pure solids and liquids aren't included in equilibrium constant expression
  2. Effect on equilibrium constant if equation is reversed? A coefficient is added? You add equations together?
    • Reversed: Kbackward = 1/Kforward
    • Coefficent: Knew = Knoriginal
    • Addition: Knew = K1 x K2
  3. Relationship between Kp and Kc
    • KP = Kc x (RT)Δn
    • Δn = moles gas products - moles gas reactants
    • note - Kp always given in atm
  4. Reaction Quotient?
    • same as equilibirum constant, but at ANY concentration.
    • Can be compared with equilibrium constant to determine how reactants/products will change
    • Q>K - [reactants] increase and [products] decrease
    • Q<K - [reactants] decrease and [products] increase
    • Q=K - [reactants] and [products] do not change
    • If rxn has only reactants Q = 0, only products Q = ∞
  5. Explain the simplification step and method of approximations
    • Simplification: assume x is very small and eliminate x from equation (+x, -x). Solve equation. If x is less than 5% of the largest initial concentration then the answer is correct.
    • Method of approximations: if x is not smaller than 5% of the largest initial concentration then input the number you got into the equation. If the new answer is not less than 5% of the largest initial concentration then input the number you just got into the equation, repeat until less than 5%!
  6. Effect of adding/removing reactants, gas volume changes, and temperature shifts
    • Adding a reactant / removing a product: rxn ---->
    • Adding a product / removing a reactant: rxn <-----
    • When volume is reduced equilibrium favors side w/ fewer moles (gases)
    • When volume is increase equilibrium favors side w/ more moles (gases)
    • Temperature: determine exothermic/endothermic. Write heat into the equation (exo - heat as product, endo - heat as reactant). Consider temperature change as a change to heat within the equation. EXAMPLE - endothermic heat increases forces equilibrium ---->