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Edexcel IAL Chemistry 11.11 Heterogeneous catalysis

Describe reactants reaching active sites and adsorbing, bonds weakening while new bonds form and products desorbing to free the surface for another cycle.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
A2

Exam points

  • Explain rate stopping when reaction mixture is separated from the solid catalyst.
  • Describe adsorption, bond weakening, surface reaction and product desorption.
  • Link porous catalyst support to greater surface area and more available active sites.

11.11—The use of a solid (heterogeneous) catalyst for industrial reactions, in the gas phase, in terms of providing a surface question 1

[Maximum number: 3]

A student investigated the kinetics of the reaction between bromate(V) ions and bromide ions in acidic conditions.

BrO3−(aq)+5Br−(aq)+6H+(aq)→3Br2(aq)+3H2O(l)\mathrm{BrO}_{3}^{-}(\mathrm{aq})+5 \mathrm{Br}^{-}(\mathrm{aq})+6 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow 3 \mathrm{Br}_{2}(\mathrm{aq})+3 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})

The presence of bromate(V) ions in drinking water is harmful to humans. Bromate(V) ions can be converted to less harmful bromide ions by passing the water through palladium with a reducing agent.

Describe how a heterogeneous catalyst, such as palladium, increases the rate of a reaction.
(3)

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