2.1.7
Rate of Reaction 2
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Rate of Reaction - Key Factors
The main factors that affect the rate of chemical reactions are:
Concentration of dissolved reactants
- Increasing the concentration increases the frequency (number) of collisions. This increases the rate of reaction.
Pressure of gas reactants
- Increasing pressure is like increasing the concentration.
- It increases the frequency (number) of collisions. This increases the rate of reaction (makes the reaction faster).
Temperature
- Increasing the temperature increases the frequency (number) of collisions.
- Increasing the temperature increases the energy of reactant particles. This means that a greater proportion (more) of the particles will have more energy than the activation energy that is needed.
- Together, these lead to more successful collisions. This increases the rate of reaction.
Surface area of solid reactants
- Increasing the surface area increases the frequency (number) of collisions. This increases the rate of reaction.
- This is often done by breaking up solids into smaller lumps (e.g. powders).
- This increase in surface area to volume ratio makes sure that more particles are exposed to attack.
Catalysts
- Catalysts are substances that increase the rate of a chemical reaction without being used up in the process.
Catalysts
Catalysts increase the rate of chemical reactions by lowering the activation energy. They do this by providing a different reaction pathway.
Not used up
- Catalysts are not used up during chemical reactions. This means that:
- They can be reused indefinitely.
- They are not found in chemical equations.
- However, catalysts will often need cleaning or regenerating, which has knock-on effects for energy expenditure and environmental impact.
Different catalysts
- Different reactions need different catalysts:
- Iron is used in the process that makes ammonia.
- Platinum and palladium are used in catalytic converters in cars.
- Enzymes catalyse reactions in biological systems.
Powders
- Catalysts often come as powders, pellets or fine gauzes because these types of substance have particularly high surface areas.
1Biology
2Chemistry
2.1Practicals
2.1.1Salts2.1.2Neutralisation2.1.3Titration2.1.4Electrolysis2.1.5Electrolysis 22.1.6Rate of Reaction2.1.7Rate of Reaction 22.1.8Chromatography2.1.9Identifying Gases2.1.10Identifying Gases 22.1.11Identifying Ions2.1.12Carbonates, Halides & Sulfates2.1.13Flame Emission Spectroscopy2.1.14Water Purification2.1.15Water Purification 2
3Physics
3.1Practicals
Jump to other topics
1Biology
2Chemistry
2.1Practicals
2.1.1Salts2.1.2Neutralisation2.1.3Titration2.1.4Electrolysis2.1.5Electrolysis 22.1.6Rate of Reaction2.1.7Rate of Reaction 22.1.8Chromatography2.1.9Identifying Gases2.1.10Identifying Gases 22.1.11Identifying Ions2.1.12Carbonates, Halides & Sulfates2.1.13Flame Emission Spectroscopy2.1.14Water Purification2.1.15Water Purification 2
3Physics
3.1Practicals
Practice questions on Rate of Reaction 2
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- 1
- 2
- 3Which of the following describe catalysts?True / false
- 4
- 5What are the consequences of catalysts not being used up?Fill in the list
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