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DP IB Chemistry: SL

Topic Questions

Home / IB / Chemistry: SL / DP / Topic Questions / 5. Energetics / Thermochemistry / 5.1 Energetics / Structured Questions: Paper 2


5.1 Energetics

Question 1a

Marks: 1
a)
Chemical reactions can be exothermic or endothermic. State which type of reaction is indicated by a decrease in temperature. 
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    Question 1b

    Marks: 1
    b)
    State the type of reaction in which the energy of the system decreases. 

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      Question 1c

      Marks: 1
      c)
      The reaction of propane with oxygen is represented by the following equation

      C3H8 + 5O2 → 3CO2 + 4H2O          ΔH = -2219 kJ mol-1

        
      State the classification of the enthalpy change is occurring in this reaction. 
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        Question 1d

        Marks: 6
        d)
        Define the term enthalpy of formation, ΔHf , and state the standard conditions. 
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          Question 2a

          Marks: 2
          a)
          Define the term enthalpy change of reaction, ΔHr

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            Question 2b

            Marks: 3
            b)
            The equations below can be identified as any of the following enthalpy changes. Identify the enthalpy change for each reaction. 
            • Enthalpy of reaction, ΔHr
            • Enthalpy of formation, ΔHf
            • Enthalpy of combustion, ΔHc
            • Enthalpy of neutralisation, ΔHneut 
              
            C2H5OH (l) + O2 (g) → CO2 (g) + H2O (l) …………………………………………
              
            CaSO3 (s) → CaO (s) + SO2 (g) ……………………………………………
              
            HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l) …………………………………………



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              Question 2c

              Marks: 2
              c)
              Hydrochloric acid, HCl (aq), and sodium hydroxide, NaOH (aq), react as follows 

              HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l)    ΔHr  = -57.9 kJ mol-1

                
              Determine the enthalpy change, in kJ, when 25 cmof 0.5 mol dm-3 hydrochloric acid reacts with 25 cmof 0.5 mol dm-3 sodium hydroxide. Give your answer to 2 decimal places. 

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                Question 3a

                Marks: 3
                a)
                A student set up apparatus for a calorimetry experiment as shown below.
                Suggest suitable materials for the lid and cup. Justify your answer. 

                IB Chem 5.1 SQ E Q3a

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                  Key Concepts
                  Calorimetry

                  Question 3b

                  Marks: 3
                  b)
                  The student added excess zinc powder to the cup with 50.0 cm3 of 1.0 mol dm-3 copper(II) sulfate solution in a calorimeter. The reaction equation was as follows:

                  Zn (s) + CuSO4 (aq)  ZnSO4 (aq) + Cu (s)

                  The maximum temperature rise was 22.6 oC. Using section 1 of the data booklet, determine the enthalpy of reaction, in kJ. Give your answer to 2 significant figures.
                  Calculate the energy change, q …………………………
                  Calculate the number of moles of copper(II) sulfate solution ………………
                  Calculate the enthalpy change of the reaction …………………

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                    Key Concepts
                    Calorimetry

                    Question 3c

                    Marks: 2
                    c)
                    Another calorimetry experiment was set up to determine the enthalpy of combustion for ethanol. 

                    6-3

                    Define standard enthalpy of combustion, ΔHc

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                      Question 3d

                      Marks: 2
                      d)
                      0.61 g of ethanol, C2H5OH, was burned in a spirit burner and used to heat 100 cm3 of water in a copper calorimeter. The temperature of the water rose by 40 oC.

                      i)
                      Using section 1 and 2 in the data booklet determine the energy, in joules, for this reaction.

                      ii)
                      Convert your answer to part (i) into kilojoules. 

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                        Key Concepts
                        Calorimetry

                        Question 3e

                        Marks: 3
                        e)
                        Calculate the enthalpy change for the combustion of ethanol.

                        Determine the moles of ethanol ………………………..
                        Determine the overall enthalpy change …………………………..

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                          Key Concepts
                          Calorimetry

                          Question 4a

                          Marks: 1
                          a)
                          4.00 g of powdered iron was reacted with 25.0 cm3 of 2.00 mol dm−3 copper(II) sulfate solution in an insulated beaker. Temperature was plotted against time.

                          5-1-ib-sl-sq-easy-q4a-calorimetry

                          Estimate the time at which the powdered iron was added to the beaker.

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                            Question 4b

                            Marks: 3
                            b)
                            A student added point Y to the graph.
                            i)
                            State what point Y indicates on the graph.
                            ii)
                            Assuming there is no heat loss in the experiment and the heat change is instantaneous, using the graph, determine the total temperature change.

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                              Question 4c

                              Marks: 1
                              c)
                              Explain why the student has recorded the temperature of the copper sulfate solution for a period of time before adding the iron powder. 

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                                Question 4d

                                Marks: 1

                                The student used the equation q = mcΔT  to calculate the enthalpy change for the reaction that took place in the beaker. State the value that the student should use for m

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