Physical Chemistry Practicals (A Level only) (AQA A Level Chemistry)

Exam Questions

3 hours30 questions
11 mark

A student is asked to investigate the initial rate of reaction for the chemical reaction between magnesium and nitric acid

Mg (s) + 2HNO3 (aq) → Mg(NO3)2 (aq) + H2 (g)

Alongside a timer, which piece of equipment would be the most appropriate to determine the initial rate of reaction?

  • Colorimeter

  • Gas syringe

  • Balance

  • Burette

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21 mark

The pH curve for the reaction of a weak acid with a strong base is shown.

q1-8-1-mcq-easy-physical-chemistry-practicals

Which row shows the correct location of the chemicals used for this reaction?

 

Burette

Conical flask

A

Ammonia

Ethanoic acid

B

Hydrochloric acid

Sodium hydroxide

C

Sodium hydroxide

Ethanoic acid

D

Ethanoic acid

Sodium hydroxide

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    31 mark

    An electrochemical cell is established using the half cells described.

    Oxidation half-cell

    Reduction half-cell

    Silver electrode in 1.0 mol dm-3

    silver(II) nitrate solution

    Copper electrode in 1.0 mol dm-3 copper(II) sulfate solution

    Which chemical is a suitable choice for the salt bridge to connect the electrochemical cell without reacting with either half-cell?

    • Barium chloride

    • Potassium chloride

    • Potassium nitrate

    • Barium nitrate

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    41 mark

    The entropy of vaporisation of water practical can be completed using a kettle.

    Which piece of information is not required to complete the calculations for this practical?

    • Power rating of the kettle

    • Temperature of the room

    • Initial mass of water

    • Final mass of water

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    51 mark

    The determination of the equilibrium constant, Kc, can be completed using the esterification reaction between propanol, C3H7OH, and ethanoic acid, CH3COOH, in the presence of a sulfuric acid catalyst.

    C3H7OH (l) + CH3COOH (l) ⇌ CH3COOC3H7 (l) + H2O (l) 

    Which is the correct Kc expression for this reaction?

    • Kcfraction numerator open square brackets C H subscript 3 C O O C subscript 3 H subscript 7 close square brackets over denominator open square brackets C subscript 3 H subscript 7 O H close square brackets open square brackets C H subscript 3 C O O H close square brackets end fraction

    • Kcfraction numerator open square brackets C subscript 3 H subscript 7 O H close square brackets open square brackets C H subscript 3 C O O H close square brackets over denominator open square brackets C H subscript 3 C O O C subscript 3 H subscript 7 close square brackets open square brackets H subscript 2 O close square brackets end fraction

    • Kcfraction numerator open square brackets C subscript 3 H subscript 7 O H close square brackets open square brackets C H subscript 3 C O O H close square brackets over denominator open square brackets C H subscript 3 C O O C subscript 3 H subscript 7 close square brackets end fraction

    • Kcfraction numerator open square brackets C H subscript 3 C O O C subscript 3 H subscript 7 close square brackets open square brackets H subscript 2 O close square brackets over denominator open square brackets C subscript 3 H subscript 7 O H close square brackets open square brackets C H subscript 3 C O O H close square brackets end fraction

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    11 mark

    The initial rate of reaction between marble chips and dilute acid can be determined by measuring the volume of gas given off per unit time and plotting a graph of the results.

    What is the reason for plotting a graph of the results?

    • The rate of reaction is a more accurate value

    • Outliers in the results can be spotted and discarded

    • An average rate can be determined from the graph

    • The rate of reaction can be found more precisely

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    21 mark

    The EMF of an electrochemical cell can be measured using the following apparatus:

    q2-8-1-mcq-medium-physical-chemistry-practicals

    Which of the following is true?

    • electrons flow through the external circuit from copper to zinc

    • sulfate ions flow from the zinc half cell to the copper half cell

    • zinc is reduced when current flows through the cell

    • cations and anions flow through the sodium chloride solution in opposite directions

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    31 mark

    The following partially drawn pH curve was obtained in an experiment:

    rsgb9zyl-q1-8-1-mcq-easy-physica

    Which of the following could be true?

     

    Label for
    x-axis

    Solution in
    burette

    Solution in
    conical flask

    A

    volume of acid

    HCl

    NH3

    B

    volume of base

    NaOH

    CH3COOH

    C

    volume of acid

    CH3COOH

    NaOH

    D

    volume of base

    NaOH

    HCl

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      41 mark

      This question is about drawing curves and obtaining gradients in chemistry investigations.

      q4-8-1-mcq-medium-physical-chemistry-practicals

      Which of the following is not true?

      • There are an equal number of points on either side of the line of best fit

      • The hypotenuse of the gradient triangle includes at least half of the line

      • The gradient triangle starts and ends on points where the line of best fit crosses grid lines

      • The gradient in this graph is 60 over 6

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      51 mark

      Which of the following combinations could be used to make a buffer solution?

      • 40 cm3 of 0.1 mol dm-3 CH3COOH + 40 cm3 of 0.05 mol dm-3 NaOH

      • 40 cm3 of 0.1 mol dm-3 CH3COOH + 40 cm3 of 0.1 mol dm-3 NaOH

      • 20 cm3 of 0.1 mol dm-3 CH3COOH + 20 cm3 of 0.2 mol dm-3 NaOH

      • 40 cm3 of 0.1 mol dm-3 CH3COOH + 20 cm3 of 0.2 mol dm-3 NaOH

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      11 mark

      A student performed a rate of reaction experiment and plotted the results on a graph.

      q1-8-1-hard-mcq-physical-chemistry-practicals

      Which can be deduced from this graph?

      • The reaction is a first order reaction

      • The reaction has reached equilibrium

      • The reaction has gone to completion

      • The rate of reaction is constant

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      21 mark

      Use the table of electrode potentials to answer this question.

      Electrode half-equation

      EӨ / V

      Fe3+ (aq) + e → Fe2+(aq)

      +0.77

      I2 (s) + 2e → 2I (aq)

      +0.54

      S4O82– (aq) + 2e → 2S2O32– (aq)

      +0.12

      A student made some predictions and then carried out a series of test tube reactions to test her predictions. Which row correctly describes a prediction and result?

       

      Prediction

      Result

      A

      Fe3+ + I2 = no reaction

      Colourless solution

      B

      Fe3+ + S2O32– = reaction

      Yellow solution

      C

      I + S2O32–  = no reaction

      No visible change

      D

      Fe3+ + I- = no reaction

      Yellow solution

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        31 mark

        A student plotted a titration curve for the reaction between a weak acid and a strong base. The initial pH of the acid was 2.52. The student identified the half equivalence point from the curve and found the pH to be 3.75.

        What was the approximate initial concentration of the acid in mol dm-3?

        • 0.003

        • 17.0

        • 0.05

        • 1.0 x 10-5

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        41 mark

        A student carried out an iodine clock reaction using hydrogen peroxide and potassium iodide in acidic conditions:

        H2O2 (aq) + 2I (aq) + 2H+ (aq) → I2 (aq) + 2H2O (l)

        The reaction is zero order with respect to the acid. The following data was obtained:

        Experiment

        [I-]/ mol dm-3

        [H2O2]/mol dm-3

        [H+]/mol dm-3

        Rate/mol dm-3s-1

        1

        0.0364

        0.0364

        0.0100

        6.94 x 10-6

        2

        0.0364

        0.0728

        0.0100

        1.39 x 10-5

        3

        0.0728

        0.0364

        0.0100

        1.39 x 10-5

        What is the unit of the rate constant?

        • mol dm-3 s-1

        • s-1

        • mol-1 dm3 s-1

        • mol2 dm-6 s-1

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        51 mark

        A student attempted to find the entropy of vaporisation of water using a 3 kW kettle and balance. He boiled 1 kg of water for 100 s and measured the mass of the kettle before and after boiling.

        What assumption is not made in determining the entropy change?

        • The mass change in the kettle is entirely due to loss of water by evaporation

        • The free energy change, ΔG, at the boiling point is zero

        • The kettle supplies energy at a constant rate

        • The density of the water is 1 g cm-3

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