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Equilibrium Constant Calculations quiz

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  • What information do you need to calculate the equilibrium constant (Kc) for a reaction?
    You need the equilibrium concentrations of all reactants and products involved in the reaction.
  • How is the equilibrium constant expression (Kc) written for a reaction involving only gases?
    Kc is written as the ratio of the concentrations of products to reactants, each raised to the power of their stoichiometric coefficients.
  • Which states of matter are excluded from the equilibrium constant expression?
    Solids and liquids are excluded from the equilibrium constant expression.
  • What is the Kc expression for the reaction: CH4(g) + CO2(g) ⇌ 2CO(g) + 2H2(g)?
    Kc = [CO]^2[H2]^2 / ([CH4][CO2])
  • If the equilibrium concentrations are [CH4]=0.255 M, [CO2]=1.10 M, [CO]=0.388 M, and [H2]=0.250 M, how do you set up the Kc calculation?
    Plug the values into the expression: Kc = (0.388^2 × 0.250^2) / (0.255 × 1.10).
  • What is the calculated value of Kc for the given example, before rounding?
    The calculated value of Kc before rounding is 0.033543762.
  • How many significant figures should the final Kc value have in this example?
    The final Kc value should have 3 significant figures, matching the given concentrations.
  • What is the final rounded value of Kc for the example reaction?
    The final rounded value of Kc is 0.0335.
  • Does the equilibrium constant Kc have units in this example?
    No, the equilibrium constant Kc is dimensionless in this example.
  • What does the value of the equilibrium constant Kc represent?
    It represents the ratio of product and reactant concentrations at equilibrium.
  • Can the equilibrium constant be used to find a missing equilibrium concentration?
    Yes, if Kc and all but one equilibrium concentration are known, the missing value can be calculated.
  • Why are the concentrations in the Kc expression raised to a power?
    They are raised to the power of their respective stoichiometric coefficients from the balanced equation.
  • What should you do if the equilibrium constant calculation gives a long decimal?
    You should round the answer to the correct number of significant figures based on the data provided.
  • Why are all species included in the Kc expression for the given example?
    All species are gases, and only gases and aqueous species are included in Kc expressions.
  • What fundamental concept in chemical thermodynamics does the equilibrium constant illustrate?
    It illustrates the relationship between the concentrations of products and reactants at equilibrium.