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Chemical Equilibrium quiz #2

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Terms in this set (20)

  • Consider the following reactions: A ⇌ B, K1 = 3.76; A ⇌ C, K2 = 2.00. What is K for the reaction C ⇌ B?
    K = K1 / K2 = 3.76 / 2.00 = 1.88
  • When any reversible reaction is at equilibrium, what conditions are necessarily true?
    The rates of the forward and reverse reactions are equal, and concentrations remain constant.
  • A chemical reaction has reached equilibrium when what occurs?
    The forward and reverse reaction rates are equal, and concentrations of all species remain constant.
  • For the following acid-base reaction, predict which side of the equilibrium is favored.
    The side favored is determined by the relative strengths of the acids and bases involved and the value of K.
  • Select all the true statements regarding chemical equilibrium.
    At equilibrium, forward and reverse reaction rates are equal, concentrations remain constant, and reactions continue at the molecular level.
  • Using reaction free energy, how can you predict equilibrium composition?
    If the free energy change (ΔG) is negative, products are favored; if positive, reactants are favored; at equilibrium, ΔG = 0.
  • Why do chemical reactions not always go to completion, leaving some reactant present at equilibrium?
    Some reactions are reversible, so both forward and reverse processes occur, resulting in a constant amount of reactant and product at equilibrium.
  • What does the plateau in concentration graphs of reactants and products indicate about a chemical reaction?
    A plateau shows that the concentrations of reactants and products have become constant, signifying the system has reached equilibrium.
  • Which states of matter are excluded when calculating the equilibrium constant K?
    Solids and liquids are excluded from the equilibrium constant expression; only gases and aqueous species are included.
  • How are the equilibrium constants Kp and Kc related for gaseous reactions?
    Kp and Kc are related by the equation Kp = Kc(RT)^(Δn), where Δn is the difference in moles of gaseous products and reactants.
  • When has a chemical reaction reached equilibrium?
    A chemical reaction has reached equilibrium when the concentrations of reactants and products remain constant over time, indicating that the forward and reverse reaction rates are equal.
  • What does the condition 'ad = as' refer to in the context of equilibrium?
    The condition 'ad = as' refers to equilibrium, meaning that the rate at which reactants are converted to products equals the rate at which products are converted back to reactants.
  • How is dynamic equilibrium best described in chemical reactions?
    Dynamic equilibrium is a state in which the forward and reverse reactions continue to occur at equal rates, resulting in constant concentrations of reactants and products.
  • How is equilibrium defined in a chemical system?
    Equilibrium is defined as the point at which the rates of the forward and reverse reactions are equal, causing the concentrations of reactants and products to remain unchanged over time.
  • What characterizes a system at equilibrium?
    A system at equilibrium is characterized by constant concentrations of reactants and products, with ongoing forward and reverse reactions occurring at equal rates.
  • How can two phases be described as being in dynamic equilibrium?
    Two phases are in dynamic equilibrium when the rate of transfer from one phase to the other equals the rate of transfer in the opposite direction, resulting in constant amounts in each phase.
  • What statement accurately describes a reaction at equilibrium?
    At equilibrium, the forward and reverse reaction rates are equal, and the concentrations of reactants and products remain constant over time.
  • Which phrase defines chemical equilibrium?
    Chemical equilibrium is defined as the state in which the forward and reverse reactions occur at equal rates, leading to constant concentrations of all species involved.
  • How is chemical equilibrium correctly described?
    Chemical equilibrium is correctly described as a dynamic state where the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products do not change.
  • What types of changes can reach dynamic equilibrium?
    Reversible physical or chemical changes, such as phase changes or chemical reactions where both forward and reverse processes occur, can reach dynamic equilibrium.