GCSEChemistryOCRChemistry A (Gateway)Exam Questions5. Monitoring & Controlling Chemical ReactionsControlling Reactions

Controlling Reactions (OCR GCSE Chemistry A (Gateway)): Exam Questions

Exam code: J248

1 hour25 questions

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Controlling Reactions

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11 mark

A student investigates the reaction between sodium carbonate and dilute nitric acid. She does all the experiments using the

  • same temperature

  • same mass of sodium carbonate

  • same volume of nitric acid.

She uses four different concentrations (A, B, C and D) of nitric acid.

For each concentration, she measures the time for the reaction to complete.

Which concentration of nitric acid gives the fastest reaction?

Concentration

Time for reaction to complete (in seconds)

A

41

B

74

C

135

D

67

    Choose your answer

    21 mark

    Which statement about catalysts is correct?

    • A catalyst decreases the activation energy of a reaction.

    • A catalyst increases the activation energy of a reaction.

    • A catalyst increases the time for a reaction to go to completion.

    • A catalyst slows down a reaction.

    Choose your answer

    31 mark

    Why do marble chips react faster with warm hydrochloric acid than with cold hydrochloric acid?

    • The warm hydrochloric acid acts as a catalyst.

    • The warm hydrochloric acid has more crowded particles.

    • The warm hydrochloric acid has particles with more energy.

    • The warm hydrochloric acid has particles that move slower.

    Choose your answer

    41 mark

    Why does increasing concentration increase the rate of reaction?

    • The particles have more kinetic energy.

    • There are more particles per unit volume.

    • There are more surfaces available for collisions

    • The activation energy is lowered

    Choose your answer

    51 mark

    What name is given to a catalyst in biological systems?

    • Transition metals

    • Acid

    • Polymer

    • Enzyme

    Choose your answer

    1
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    The rate of a reaction was monitored by recording the volume of gas produced every 5 seconds.

    TIUbhf1t_q1

    What is the mean rate of reaction in the first 10 seconds of the reaction, in cm3/s?

    • 2.9

    • 3.0

    • 3.5

    • 2.5

    Choose your answer

    2
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    Hydrogen peroxide, H2O2, quickly decomposes to produce water and oxygen when a catalyst is added to the solution:

    2H2O2 (aq) → 2H2O (l)  + O2 (g)

    The volume of gas produced was measured and is shown in the graph below:

    TIUbhf1t_q1

    Which statement is not true for this reaction?

    • The reaction finishes after 30 seconds

    • The mean rate of reaction in the first 5 seconds is 2.5 cm3/s

    • The final volume of gas produced is 60 cm3

    • The concentration of the hydrogen peroxide decreases during the reaction

    Choose your answer

    3
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    Magnesium metal reacts with an excess of hydrochloric acid solution to form magnesium chloride and hydrogen:

    Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)

    Which of the following will not increase the rate of this reaction?

    • Increase the temperature of the acid

    • Increase the surface area to volume ratio of the pieces of magnesium

    • Increase the concentration of the hydrochloric acid

    • Increase the volume of hydrochloric acid solution used

    Choose your answer

    41 mark

    Catalysts are often used in chemical reactions.

    Which letter represents two correct features of catalysts?

     

    Feature 1

    Feature 2

    A

    Lower activation energy for the reaction

    More products made in total

    B

    Alternative pathway for the reaction is provided

    Not used up over the course of the reaction

    C

    Makes industrial processes cheaper

    Metal catalysts are cheap to buy

    D

    Reduce the overall energy change of the reaction

    Can be present in biological systems as enzymes

      Choose your answer

      51 mark

      Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water and carbon dioxide:

      CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + H2O (l) + CO2 (g)

      Which statement is not true if the temperature of the reaction decreases?

      • The frequency of the collisions between particles decreases

      • The collisions are less energetic

      • The activation energy increases

      • There are fewer particles with the minimum energy to react

      Choose your answer

      61 mark

      The rate of a reaction can be changed by adding a catalyst to the reaction mixture.

      Which line of the table shows how the rate of reaction and the mass of the catalyst change as the reaction takes place?

       

      Change in rate of reaction

      Change in mass of catalyst

      A

      decreases

      no change

      B

      no change

      decreases

      C

      increases

      no change

      D

      increases

      decreases

        Choose your answer

        71 mark

        A student investigates the decomposition of hydrogen peroxide.

        2H2O2 (aq) → 2H2O (l) + O2 (g)

        0.2 g of oxygen gas is produced in the reaction.

        The student uses 0.5 g of manganese(IV) oxide as a catalyst in the reaction.

        How much manganese(IV) oxide remains at the end of the reaction?

        • 0.2 g

        • 0.3 g

        • 0.5 g

        • 0.7 g

        Choose your answer

        81 mark

        Enzymes are a type of catalyst.

        Which of the following catalysts is an example of an enzyme?

        • Amylase – a catalyst found in human saliva.

        • Iron – a catalyst used in the Haber process.

        • Manganese(IV) oxide – a catalyst used in the decomposition of hydrogen peroxide.

        • Vanadium(V) oxide – a catalyst used in the Contact process.

        Choose your answer

        9
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        A student investigates the reaction between calcium carbonate and hydrochloric acid.

        He measures the total volume of gas made every minute.

        Look at the graph. It shows his results for the experiment.

        q8-paper-4-specimen-2016-ocr-gcse-chem

        What is the rate of reaction between 0 and 2 minutes, in cm3/minute?

        • 7.5

        • 15

        • 30

        • 60

        Choose your answer

        101 mark

        A catalyst can be used to increase the rate of a reaction.

        Which graph shows the mass of the catalyst as the reaction takes place?

        • q8a-paper-4-june-2019-ocr-gcse-chem
        • q8b-paper-4-june-2019-ocr-gcse-chem
        • q8c-paper-4-june-2019-ocr-gcse-chem
        • q8d-paper-4-june-2019-ocr-gcse-chem

        Choose your answer

        11 mark

        A student investigates the reaction between zinc and dilute sulfuric acid.

        He measures the time taken to collect 50 cm3 of hydrogen gas. This time is 65 seconds.

        The student investigates four substances which are possible catalysts for the reaction.

        Substance

        Appearance of substance

        Time to collect 50 cm3 of hydrogen (g)

        Other observations

        A

        red-brown powder

        19

        red-brown powder remains

        B

        blue solid

        15

        colourless solution formed

        C

        red-brown lumps

        65

        red-brown lumps remain

        D

        white solid

        65

        colourless solution formed

        Which substance, A, B, C or D, is a catalyst for the reaction?

          Choose your answer

          21 mark

          The rate of reaction of marble chips with dilute hydrochloric acid depends on the surface area of the marble chips.

          Which surface area of the marble chips gives the highest rate of reaction?

          • 0.673 mm2

          • 1030 mm2

          • 2.18 × 103 mm2

          • 4.98 × 10–2 mm2

          Choose your answer

          3
          Sme Calculator          1 mark

          Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas:

          Mg (s) + 2HCl (aq) rightwards arrowMgCl2 (aq) + H2 (g)

          During the first 10 s of the reaction, 1.2 g of magnesium was used up.

          Calculate the mean rate of reaction in mol/s for this part of the reaction.

          The relative atomic mass, Ar, of H is 1, of Mg is 24 and of Cl is 35.5.

          • 2.9 mol/s

          • 2.0 mol/s

          • 0.05 mol/s

          • 0.005 mol/s

          Choose your answer

          4
          Sme Calculator          1 mark

          A student investigates the reaction between 1.0 g of calcium carbonate and 20 cm3 of 1.0 mol/dm3 hydrochloric acid at 25 ºC.

          The student does two experiments.

          • He uses different sized pieces of calcium carbonate for each experiment.

          • The rate of reaction is greater in the first experiment.

          Which is the best explanation for this result?

          • Large pieces of calcium carbonate have a larger surface area resulting in less frequent collisions.

          • Large pieces of calcium carbonate have a smaller surface area resulting in more frequent collisions.

          • Small pieces of calcium carbonate have a larger surface area resulting in less frequent collisions.

          • Small pieces of calcium carbonate have a larger surface area resulting in more frequent collisions.

          Choose your answer

          51 mark

          The graph shows the volume of hydrogen gas made in an experiment.

          screenshot-2024-11-06-205937

          What is the rate of reaction when the time is 20s?

          • 0.44 cm3/s

          • 2.25 cm3/s

          • 25 cm3/s

          • 900 cm3/s

          Choose your answer