chemical equillibrium

• At equilibrium, the rates of the forward and reverse reactions are equal.
• The Haber process is a process used for the synthesis of ammonia.
• Changing the temperature will change the value of an equilibrium constant.
• The equilibrium-constant expression depends on the stoichiometry of the reaction.
• Which of the following statements is true?

  Q is the same as Keq when a reaction is at equilibrium.
• The reaction is at equilibrium when Q=Keq.
• The effect of a catalyst on an equilibrium is to increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture.
• The effect of a catalyst on a chemical reaction is to react with product, effectively removing it and shifting the equilibrium to the right.

  FALSE
• At constant temperature, reducing the volume of a gaseous equilibrium mixture causes the reaction to shift the direction that increases the number of moles of gas in the system.

  FALSE
• In an exothermic reaction, increasing the reaction temperature favors the formation of reactants.

  TRUE
• Le Chatelier's principle states that if a system at equilibrium is disturbed, the equilibrium will shift to minimize the disturbance.

  TRUE
• Chemical Equilibrium


  State of balance where the rate of forward and reverse reactions are equal, resulting in no net change over time
• Chemical Equilibrium


  • Static
  • Dynamic
• Chemical Equilibrium


  1. Forward rate = Reverse rate

  2. No net change over time
• Equilibrium Constant (K)


  The quantity that represents the extent of a reaction, the larger the K the more the reaction proceeds towards products
• Hemoglobin in placenta has a higher affinity for oxygen than hemoglobin in maternal blood
• Hemoglobin in placenta (Hb)

  Affinity for oxygen (KF(Hb)) is greater than hemoglobin in maternal blood (Km(Hb))
• Kinetic rate law


  Rate = k[A]^m[B]^n, where k is the rate constant and m,n are the orders of the reaction
• For an elementary reaction, the rate law is simply Rate = k[A][B]
• Reaction Mechanism


  1. Substrate binding

  2. Transition state facilitation

  3. Catalysis

  4. Product release
• Equilibrium Constant (Kc)


  Expressed in terms of concentrations (M)
• Equilibrium Constant (Kp)


  Expressed in terms of partial pressures (atm)
• Kc and Kp are numerically equal when all reactants and products are gases
• Kc = Kp(RT)^(Σν_products - Σν_reactants)
• The equilibrium constant (K) does not change with time once equilibrium is established
• At equilibrium, the concentrations of reactants and products remain constant
• The reaction quotient (Q) determines the direction the reaction will shift to reach equilibrium
• If Q < K, the reaction will shift to the right to increase product concentrations
• If Q > K, the reaction will shift to the left to increase reactant concentrations
• Le Chatelier's Principle


  • If a system at equilibrium is disturbed, it will shift in the direction that counteracts the disturbance to re-establish equilibrium
• Increase in reactant concentration

  Reaction shifts to the right to consume the added reactant
• Increase in product concentration


  Reaction shifts to the left to consume the added product
• Increase in pressure


  Reaction shifts to the side with fewer moles of gas

  
• Increase in temperature


  Exothermic reactions shift left, endothermic reactions shift right

  
• Catalysts do not affect the equilibrium position, they only speed up the rate at which equilibrium is reached
• The Haber process for producing ammonia is an exothermic reaction, so lower temperatures favor higher ammonia yields
• The enzyme nitrogenase catalyzes the fixation of nitrogen to produce ammonia