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DP IB Chemistry: SL

Topic Questions

Home / IB / Chemistry: SL / DP / Topic Questions / 7. Equilibrium / 7.1 Equilibrium / Structured Questions: Paper 2


7.1 Equilibrium

Question 1a

Marks: 1
a)
Distinguish between the terms reaction quotient, Q, and equilibrium constant, Kc.
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    Question 1b

    Marks: 1
    b)
    Write an expression for the reaction quotient, Q, for this reaction.

    2SO2 (g) + O2 (g) not stretchy rightwards harpoon over leftwards harpoon 2SO3 (g)

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      Key Concepts
      The Reaction Quotient

      Question 1c

      Marks: 1
      c)
      The equilibrium constant, Kc, for the reaction is 0.282 at temperature T whilst the reaction quotient is calculated to be 0.5.

                Deduce the direction of the initial reaction.

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        Key Concepts
        The Reaction Quotient

        Question 2a

        Marks: 1
        a)
        Urea can be made by the direct combination of ammonia and carbon dioxide gases.

        2NH3 (g) + CO2 (g) not stretchy rightwards harpoon over leftwards harpoon CO(NH2)2 (g) + H2O (g) 

           Write the equilibrium constant expression, Kc.

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          Question 2b

          Marks: 1
          b)
          ΔH < 0 for the forward reaction.

             Predict the effect on the equilibrium constant, Kc, when the temperature is increased.

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            Question 2c

            Marks: 1
            c)
            Predict what will happen to the equilibrium position if there is a decrease in pressure.
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              Question 2d

              Marks: 1
              d)
              The Kc value for the reaction is determined to be 2 x 10-9 mol dm-3    at 298 K.

                 Determine the magnitude of Kc if the reaction is reversed.

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                Question 3a

                Marks: 1
                a)
                The following reaction was allowed to reach equilibrium at 761 K.

                H2 (g) + I2 (g) not stretchy rightwards harpoon over leftwards harpoon 2HI (g)               ΔHθ < 0

                   Determine the Kc expression for this reaction.

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                  Question 3b

                  Marks: 1
                  b)
                  The Kc value for the reaction in part a) is found to be 48.52.

                     Deduce the Kc value for the following reaction.

                  1/2H2 (g) + 1/2I2 (g) rightwards harpoon over leftwards harpoon HI (g)  

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                    Question 3c

                    Marks: 1
                    c)
                    The temperature of the reaction is increased to 703K and the new Kvalue is found to be 54.30.

                       Explain why the value of Kc has changed.

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                      Question 3d

                      Marks: 1
                      d)
                      A catalyst is added in an attempt to speed up the rate of reaction.

                         State what will happen to the value of Kc.

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                        Question 4a

                        Marks: 1
                        a)
                        State what is meant by the term dynamic equilibrium.
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                          Question 4b

                          Marks: 2
                          b)
                          Describe two characteristics of a reaction at equilibrium.
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                            Question 4c

                            Marks: 2
                            c)
                            State and explain the effect of a catalyst on the position of equilibrium.
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                              Question 4d

                              Marks: 1
                              d)
                              Methanoic acid reacts with methanol to form the ester methyl methanoate.

                              HCOOH (l) + CH3OH (l) rightwards harpoon over leftwards harpoon HCOOCH3 (l) + H2O (l)

                              The esterification reaction is exothermic. State the effect of increasing temperature on the value of the equilibrium constant (Kc) for this reaction.

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