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DP IB Chemistry: HL

Topic Questions

Home / IB / Chemistry: HL / DP / Topic Questions / 15. Energetics/Thermochemistry (HL only) / 15.1 Energy Cycles / Structured Questions: Paper 2


15.1 Energy Cycles

Question 1a

Marks: 3
a)
Write one equation to represent each the following changes:

Atomisation of sodium ………………………………………………………………….

First ionisation energy of magnesium ………………………………………………………………….

First electron affinity of chlorine ………………………………………………………………….
[3]
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    Key Concepts
    Key Enthalpy Terms

    Question 1b

    Marks: 2
    b)
    Give the definition of the term enthalpy of lattice formation.
    [2]



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      Key Concepts
      Key Enthalpy Terms

      Question 1c

      Marks: 3
      c)
      Study the following Born-Haber cycle.

      ib-chem-hl-sq-15-1-e-q1c-b-h-cycle-agf

         State the enthalpy changes for the following steps: 

      Step 1 ………………………………………………………………………………………………..

      Step 3 ………………………………………………………………………………………………..

      Step 4 ………………………………………………………………………………………………..
      [3]

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        Question 1d

        Marks: 3
        d)
        The enthalpy of lattice formation of potassium fluoride and caesium fluoride is -829 kJ mol-1 and -759 kJ mol-1 respectively.

        With reference to the ions in the structure, explain why the enthalpy of lattice formation i
        s more exothermic for potassium fluoride.
        [3]
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          Question 2a

          Marks: 1
          a)
          State the equation to determine the standard enthalpy change of solution, ΔHsol.
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            Question 2b

            Marks: 2
            b)
            Use sections 18 and 20 in the data booklet to determine the enthalpy change of solution, ΔHsol, in kJ mol-1, of sodium chloride, NaCl. 
            [2]
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              Question 2c

              Marks: 3
              c)
              Part of the dissolution cycle for magnesium bromide is shown below. Complete the cycle.

              ib-chem-hl-sq-15-1-e-q2c-mgbr2-cycle
              [3]
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                Question 2d

                Marks: 2
                d)
                The lattice enthalpy ΔHlatt , of magnesium bromide is 2421 kJ mol-1. Using section 20 of the data booklet and your answer to part c), determine the enthalpy of solution, ΔHsol , in kJ mol-1 of magnesium bromide. 
                [2]
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                  Question 2e

                  Marks: 2
                  e)
                  The enthalpy of hydration for the calcium ion , ΔHhyd(Ca2+, is 1616 kJ mol-1 . Explain why this value is less exothermic than the value for the enthalpy of hydration for the magnesium ion , ΔHhyd(Mg2+)
                  [2]
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                    Question 3a

                    Marks: 3
                    a)
                    State the definition of electron affinity, ΔHea.
                    [3]
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                      Key Concepts
                      Key Enthalpy Terms

                      Question 3b

                      Marks: 2
                      b)
                      Electron affinities can be represented using equations.

                      i)
                      State the equation which represents the first electron affinity of oxygen.
                      [1]
                      ii)
                      State the equation which represents the second electron affinity of oxygen.

                      [1]

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                        Key Enthalpy Terms

                        Question 3c

                        Marks: 2
                        c)
                        The first and second electron affinities of oxygen are shown in the table below.

                        First electron affinity of O -141 kJ mol-1 Exothermic
                        Second electron affinity of O +844 kJ mol-1 Endothermic

                        State why the second electron affinity of oxygen is an endothermic process.

                        [2]

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                          Question 4a

                          Marks: 2
                          a)
                          The incomplete Born-Haber cycle for silver fluoride, AgF, is shown below.
                          4f157c5f-edcc-4420-a0a6-eb114baa5c79

                          Complete the Born Haber cycle. 
                          [2]
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                            Question 4b

                            Marks: 2
                            b)
                            Use the Born-Haber cycle in part a) and sections 8 and 11 in the data booklet to determine the enthalpy changes, in kJ mol-1, of the following.

                            The enthalpy of atomisation of silver, ΔHat(Ag) , is +289 kJ mol-1
                            The enthalpy of atomisation of fluorine, ΔHat(F) , is +79 kJ mol-1

                            ΔHat(Ag) + ΔHie(Ag) ................................................................

                            ΔHat(F) + ΔHea(F) ................................................................
                            [2]
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                              Question 4c

                              Marks: 3
                              c)
                              Use your answer to part b) and the lattice enthalpy of silver fluoride, ΔHlatt(AgF) , in section 18 in the data booklet to determine the enthalpy of formation of silver fluoride, ΔHf(AgF), in kJ mol-1
                              [3]
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                                Question 5a

                                Marks: 1
                                a)
                                The equipment set up below is used to measure the enthalpy change for a reaction.

                                3-11

                                Suggest why a polystyrene cup is used for this experiment.
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                                  Question 5b

                                  Marks: 3
                                  b)
                                  A student added 50.00 cm3 of 1.50 mol dm-3 copper sulfate solution, CuSO4 (aq), to the polystyrene cup. They recorded the temperature every minute for 3 minutes. On the fourth minute, 6.00 g of powdered zinc was added. They then recorded the temperature of the reaction mixture every minute for a further 7 minutes. The maximum temperature change was estimated to be 29.0 °C. 

                                  Use section 6 of the data booklet to answer the following questions.

                                  i)
                                  Determine the amount, in moles, of copper sulfate used in the reaction.
                                  [1]
                                  ii)
                                  Determine the amount, in moles, of powdered zinc used in the reaction.
                                  [1]
                                  iii)
                                  Determine the limiting reagent in the reaction.
                                  [1]
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                                    Question 5c

                                    Marks: 3
                                    c)
                                    Use the information in part b) and sections 1 and 2 in the data booklet to determine the following.

                                    i)
                                    The energy change, in J, for the reaction.
                                    [1]
                                    ii)
                                    The enthalpy change, in kJ mol-1, for the reaction between copper sulfate and zinc. 
                                    [2]
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