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Chemistry · May / June 2026 · Paper 41 · Question 4

0620

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The question as text

Aqueous hydrogen peroxide, H2O2, decomposes to produce water and oxygen gas. Manganese(IV) oxide is a catalyst in this reaction. A student adds powdered manganese(IV) oxide to aqueous hydrogen peroxide in a conical flask as shown in Figure 4.1. The volume in the gas syringe is measured at regular time intervals. The volume increases as time increases. manganese(IV) oxide hydrogen peroxide gas syringe Figure 4.1

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  • 4(a)[3]

    2H2O2(aq) → 2H2O(l) + O2(g)

    M1 all three formulas correct(1)

    M2 equation correct(1)

    M3 state symbols(1)

  • 4(b)[2]

    M1 increases the rate of a reaction(1)

    M2 unchanged at the end of the reaction(1)

  • 4(c)(i)[1]

    Answers must be based on

    EITHER concentration

    OR distance between particles

    OR collision frequency

    concentration (of hydrogen peroxide or reactant) is highest (at the start)

    OR

    particles or molecules (of hydrogen peroxide or reactant) are closest (at the start)

    OR

    collision frequency

    (of hydrogen peroxide particles or molecules or reactant) is highest (at the start)

  • 4(c)(ii)[1]

    the hydrogen peroxide is used up

    OR

    ALL the hydrogen peroxide has reacted or decomposed

  • 4(d)[3]

    M1 kinetic energy of particles is lower(1)

    M2 frequency of collisions between particles is lower(1) M3 fewer or lower percentage or lower proportion or lower fraction of particles have energy greater than / equal to activation energy

    OR

    fewer of the collisions or lower percentage or lower fraction of collisions have energy greater than or equal to activation energy(1)

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