Catalysts
Select Lesson
Exam Board
Select an option
Chemistry practicals
Using resources
Chemistry of the atmosphere
Rates of reaction and equilibria
Energy changes
Chemical changes
Quantitative chemistry
Bonding, structure and properties of matter
Atomic structure and the periodic table
Practical skills
Explainer Video
Summary
Catalysts
In a nutshell
Catalysts increase the rate of reaction by providing an alternative pathway for the reaction to occur. They do not get used up in the reaction.
Catalysts
Definition
A catalyst is a substance which increases the rate of reaction by providing an alternative reaction pathway for the reaction to occur. This is done by decreasing the activation energy, so more particles have at least the minimum energy required to collide, leading to a reaction. This is represented in the reaction profile below.
 |
|
Some important points about catalysts:
- They do not get used up during the reaction.
- They do not interfere with a reaction, therefore the reactants and products will remain the same.
- A small amount of catalyst can be used for a large amount of reactants.
- They are very specific.
Examples
Catalyst | Reaction |
| Manganese () oxide () | Speeds up the decomposition of hydrogen peroxide into water and oxygen. |
| Nickel () | Hydrogenation of unsaturated hydrocarbons. |
Identifying catalysts
To identify whether a substance is a catalyst or not you can run a reaction without this substance and measure the rate of reaction. Then, add this potential catalyst and run the experiment again. Measure the rate of reaction again and if it increases then it is likely that the substance is a catalyst.
Enzymes
Definition
Enzymes are biological catalysts. They speed up biochemical reactions in living organisms. Enzymes are involved in processes such as respiration and photosynthesis. Enzymes are also involved in fermentation, where enzymes from yeast cells are used to make alcoholic beverages. The enzymes catalyse the reaction of sugars to form ethanol and carbon dioxide.
Examples
Enzyme | Reaction |
| Lactase | Breaks down lactose into glucose and galactose. |
| Catalase | Breaks down hydrogen peroxide into water and oxygen. |
FAQs - Frequently Asked Questions
What is an enzyme?
Enzymes are biological catalysts. They speed up biochemical reactions in living organisms.
Do catalysts get used up in a reaction?
Catalysts do not get used up during the reaction.
What is a catalyst?
A catalyst is a substance which increases the rate of reaction by providing an alternative reaction pathway for the reaction to occur.