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Chapter 11 Practice Paper: Energy changes — question paper

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GCSE (9–1) · GCSE Chemistry (Foundation and Higher)

Chapter 11 Practice Paper

Energy changes

Duration: 40 minutes
Total: 30 marks
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Class:
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Date:

READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A contains ten multiple-choice questions. Choose one answer, A, B, C or D, for each.
  • Section B contains structured questions. Write your answers in the spaces provided.
  • Bond energies will be given where needed.
  • The total mark for this paper is 30.

Original practice material written for the MOE GCSE Chemistry syllabus. It is not an official MOE or school examination paper. Chapter 11: exothermic and endothermic reactions, reaction profiles and activation energy, bond energy calculations (Higher), the temperature practical, cells and fuel cells (Chemistry-only badged).

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

  1. 1

    The temperature of a reaction mixture drops. The reaction is

    1. Aendothermic
    2. Bexothermic
    3. Ccombustion
    4. Dcomplete
    ( )
  2. 2

    Which is exothermic?

    1. APhotosynthesis
    2. BThermal decomposition of CaCO₃
    3. CCitric acid + bicarbonate
    4. DRespiration in cells
    ( )
  3. 3

    On a reaction profile, ΔH is the difference between

    1. Areactants and time
    2. Bproducts and reactants
    3. Cpeak and reactants
    4. Dpeak and products
    ( )
  4. 4

    A catalyst changes

    1. Aboth ΔH and activation energy
    2. Bneither
    3. Cthe activation energy only
    4. DΔH only
    ( )
  5. 5

    Bond making

    1. Aabsorbs energy
    2. Bneeds a catalyst
    3. Cis endothermic
    4. Dreleases energy
    ( )
  6. 6

    ΔH is calculated as

    1. Abonds broken + bonds made
    2. Bbonds made × bonds broken
    3. Cbonds broken − bonds made
    4. Dbonds made − bonds broken
    ( )
  7. 7

    In the temperature practical, the maximum temperature change identifies

    1. Athe exact reacting volumes
    2. Bthe room temperature
    3. Cthe rate constant
    4. Dthe acid concentration
    ( )
  8. 8

    A cell’s voltage is largest when the two metals are

    1. Afar apart in reactivity
    2. Bboth magnetic
    3. Cidentical
    4. Dboth unreactive
    ( )
  9. 9

    The only product of a working hydrogen fuel cell is

    1. Asteam and CO₂
    2. Bwater
    3. Ccarbon dioxide
    4. Dhydrogen peroxide
    ( )
  10. 10

    Fuel cells compared with rechargeable batteries

    1. Anever need any input
    2. Bare always cheaper
    3. Cstore more energy per gram but charge slowly
    4. Drefuel in minutes but need a continuous fuel supply
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 11

    An ice-pack sachet contains water and a bag of ammonium nitrate. Squeezing bursts the bag, and the temperature falls from 22 °C to 3 °C.

    1. (a)

      Explain, in terms of energy transfer, why the temperature falls.

      [2]
    2. (b)

      State the sign of ΔH for this process.

      [1]
    3. (c)

      On a profile of this process, state whether the products sit above or below the reactants.

      [1]
    4. (d)

      State one safety reason users are told not to reuse the sachet.

      [1]
  2. 12

    Hydrogen chloride is formed in the gas phase: H₂ + Cl₂ → 2HCl. Bond energies: H–H 436, Cl–Cl 242, H–Cl 431 kJ/mol.

    1. (a)

      Calculate the energy needed to break the reactant bonds.

      [2]
    2. (b)

      Work out the total energy given out as the new bonds form.

      [2]
    3. (c)

      Find the overall energy change and state whether the reaction is exothermic or endothermic.

      [3]
  3. 13

    A student investigates the neutralisation of hydrochloric acid by sodium hydroxide, adding 5 cm³ portions of alkali to 30 cm³ of acid and recording the maximum temperature each time.

    Results

    Volume of alkali / cm³Max temperature / °C
    018.5
    519.9
    1021.3
    1522.7
    2023.6
    2524.0
    3023.8
    3523.4
    1. (a)

      Identify the volume of alkali at which neutralisation is exact.

      [1]
    2. (b)

      Explain why the temperature falls after this volume.

      [2]
    3. (c)

      The student repeats with a lid on the cup. State and explain the effect on the results.

      [2]
    4. (d)

      Is this reaction exothermic or endothermic? Justify from the data.

      [2]
    5. (e)

      Name one error the student cannot remove by better insulation.

      [1]

— End of paper —