Factors Affecting the Rate of Reaction

The rate of a chemical reaction can be influenced by several factors:

1. Temperature – The rate of reaction increases with temperature.  

2. Pressure – In gases, higher pressure increases the rate of reaction.  

3. Surface Area / Particle Size – The rate of reaction is proportional to surface area and inversely proportional to particle size. Smaller particles react faster because they expose more surface area.  

4. Concentration of Reactants – A higher concentration leads to a faster reaction.  

5. Catalyst – A catalyst speeds up the reaction without being consumed.  

Important Note

- Factors such as pressure, surface area, and concentration (points 2 to 4) do not change the energy of particles; they only affect how often collisions occur.  

Example of Photochemical Reaction

- Substances like hydrogen peroxide (H₂O₂) and silver nitrate (AgNO₃) are stored in dark bottles to prevent decomposition by light. This is an example of a photochemical reaction.