Chemical reactions occur when new substances are formed from the collision of particles with sufficient energy and alignment. The rate of chemical reactions can be affected by several factors, including surface area, concentration, temperature, and catalysts. Increasing the surface area, concentration, or temperature of reactants increases the number of collisions and reaction rate. In industry, increasing the reaction rate is often advantageous to make products more efficiently.

1. Chemical Reactions

2. Chemical Reactions How do we know when a chemical reaction has occurred? If new substances are formed, then a chemical reaction has taken place. There are often signs that a chemical reaction is occurring. These include, light, heat, flames, smoke, gas production, a new smell, a colour change and the appearance of new substances.

3. Chemical Reactions Why do chemical reactions occur? Substances are made of billions of incredibly small particles, either atoms, ions or molecules. For substances to react, their particles must collide . For a collision to be successful, the particles must have sufficient energy, and they must be in right alignment.

4. Collisions

5. What factors affect the amount and the strength of collisions (reaction rate)? Surface Area Concentration Temperature Catalysts

6. Reaction Rate Surface area As we saw in our experiment, surface area greatly affects the _____ of the reaction. ________ the surface area increases the amount of atoms and molecules available for________, therefore increasing the rate of the _______.

7. Reaction Rate Concentration Read yellow part of page 75 and summarise how concentration affects the rate of reaction and why.

8. Reactions Rates Why is increasing the rate of a reaction often advantageous in industry? Brain storm in your book.