Reaction Rates (u1)

• Before a chemical reaction can take place, the particles of the reacting chemicals must come together (collide). This is known as collision theory.
• Factors affecting the rate of reaction: Particle size/surface area, concentration, temperature, catalysts.
• To make a solid react faster, we can use smaller particles i.e. increase the surface area: Decreasing the particle size/increasing the surface area increases the rate of reaction.
• In a concentrated solutions there are more particles in the same volume, so more successful collisions take place resulting in a faster reaction: Increasing the concentration of a reactant increases the rate of reaction.
• Increasing the temperature gives the particles more energy and makes them move faster, so increasing the number of successful collisions: Increasing the temperature increases the rate of reaction.
• Catalysts: Biological catalysts are called enzymes. These speed up the reactions which take place in living things. Enzymes are used in many industrial processes: Catalysts increase the rate of reaction without being used up.
• Rate =d/t= d difference in quantity of reactant or product\t time for the change