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Edexcel IAL Chemistry 17.32 Mn2+ autocatalysis

The rate starts slowly, rises as Mn2+ catalyst forms, then falls as manganate(VII) and ethanedioate reactants are used up.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
A2

Exam points

  • Interpret rate graphs showing slow start, acceleration and final slowing.
  • Write the Mn3+ and ethanedioate step regenerating Mn2+ and forming CO2.
  • Identify Mn2+ as the autocatalyst produced during the manganate(VII) reaction.

17.32—The role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions question 1

[Maximum number: 1]

Acidified manganate(VII) ions react with ethanedioate ions.

2MnO4−+16H++5C2O42−→2Mn2++8H2O+10CO22 \mathrm{MnO}_{4}^{-}+16 \mathrm{H}^{+}+5 \mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_{2} \mathrm{O}+10 \mathrm{CO}_{2}

The rate of this reaction increases then decreases.
What are the reasons for these changes in rate of reaction?
A
B
C
D

Table for Question 17.32—The role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions question 1 — Edexcel A-Level Chemistry A2
A

kinetic energies of particles increase then reactant concentration decreases

B

Mn2+ acts as a catalyst; concentration of reactants decreases

C

MnO4− acts as a catalyst; kinetic energies decrease

D

MnO4− acts as a catalyst; concentration of reactants decreases

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