Eduqas A-Level Chemistry A410QS
Formulae and Equations
Basic Ideas About Atoms
Chemical Calculations
Bonding
Solid Structures
The Periodic Table
Simple Equilibria and Acid-Base Reactions
Thermochemistry
Rates of Reaction
The Wider Impact of Chemistry
Organic Compounds
Hydrocarbons
Halogenoalkanes
Alcohols and Carboxylic Acids
Instrumental Analysis
Redox and Standard Electrode Potential
Redox Reactions
Chemistry of the P-Block
Chemistry of the D-Block Transition Metals
Chemical Kinetics
Enthalpy Changes for Solids and Solutions
Entropy and Feasibility of Reactions
Equilibrium Constants
Acid-Base Equilibria
Stereoisomerism
Aromaticity
Alcohols and Phenols
Aldehydes and Ketones
Carboxylic Acids and Their Derivatives
Amines
Amino Acids, Peptides and Proteins
Organic Synthesis and Analysis
Specified Practical Work
Practical Skills and Techniques
Mathematical Skills in Chemistry
Chemistry of the D-Block Transition Metals
Heterogeneous and homogeneous catalysis
- 3 things to know
- Component 1
Overview
Three stages of a reaction on a heterogeneous catalyst, how adsorption onto a surface speeds up a reaction and substance that poisons an industrial catalyst.
What you need to know
Answer each one before you reveal it.
Outline the three stages of a reaction on a heterogeneous catalyst.
Why is a poisoned transition metal catalyst so costly to an industrial process?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why are most transition metal catalysts used in a different phase from the reactants?
Model answer
The metal is a solid while the reactants are gases or in solution, so the reaction happens at the surface and the catalyst is easily recovered afterwards.
- 2
Why can a transition metal ion in solution catalyse a reaction between two other ions?
Model answer
It can be oxidised by one of them and reduced back by the other, providing a two-step route of lower activation energy and emerging unchanged.
- 3
Where does the reaction take place on a heterogeneous catalyst?
Model answer
On its surface, at positions called active sites.
- 4
Outline the three stages of a reaction on a heterogeneous catalyst.
Model answer
The reactant molecules are adsorbed onto the surface, they react there, and the products are then desorbed.
- 5
Explain how adsorption onto a surface speeds up a reaction.
Model answer
It holds the reactants close together in a favourable orientation and weakens their bonds, which lowers the activation energy.
- 6
Why is a heterogeneous catalyst usually used as a fine powder or as a thin coating on a support?
Model answer
This gives the greatest surface area per unit mass, so more active sites are available and less of the costly metal is needed.
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