1. What is a chemical reaction?
-a process in which a substance changes into an entirely different substance.
Two main components of a chemical reaction are a:
Reactant
Product

2. Reactants vs Products Reactants – the starting materials in a reaction
(what we start with)
Products – are the materials produced from the reaction
(what we end with)

3. The arrow always points to the products
Reactants Products
The arrow always points to the products

4. 2H2 + O2 2H2O C + O2 CO2

5. Chemical Reaction
During a chemical reaction, the reactants and the products have the same atoms. They just rearrange partners and switch partners.
Chemical bonds break in the reactants and new chemical bonds form in the products.

6. Why must both the reactant and the products have the same number and kinds of atoms?
It’s the law – the law of conservation of mass
Matter cannot be created or destroyed
In every chemical reaction, the mass of the matter in the products must equal the mass of the reactants.

7. Law of Conservation of Mass
Matter can’t be created or destroyed
The mass of the products must equal the mass of the reactants.
Same number/kinds of elements on both sides

8. How A Reaction Works

9. CH4 + H2O CO + 3H2 CO + H2O CO2 + H2
The arrow always points to the products

11. Energy in a Reaction
Endothermic Reaction – a chemical reaction that absorbs heat energy from its environment.
Exothermic Reaction – a chemical reaction that releases heat energy to its environment

12. Endothermic Exothermic
Melting Ice
Boiling Water
Baking Bread
Cooking an Egg
Burning a match
Ice Forming
Calcium Chloride with Water (Did in class)
Mixing water with strong acids.

13. Photosynthesis – the process of turning sunlight into food
Light energy to chemical energy
6CO + 6H20 C6H12O6 + 6O2
Respiration (Cellular Respiration) – the process of turning sugar and oxygen into carbon dioxide and water.
C6H12O6 + 6O2 6CO + 6H20

14. Reactions Rates Think of rate as how fast or slow the reaction happens
What factors influence how fast a reaction happens?

15. 4 Factors that Influence Reaction Rates
Temperature or reactants
Concentration of reactants
Surface area of reactants
Presence of a catalyst

16. Temperature of Reactants
Higher temperatures react faster than cooler temperatures

17. Concentration of Reactants
Concentration is the number of particles in a given volume
The higher the concentration the faster the reaction
The lower the concentration the slower the reaction

18. Surface Area of Reactants
The more surface (matter) area exposed the faster it reacts
Presence of a Catalyst
Something we add to a reaction to speed it up.
IS NOT a reactant and is not consumed in the reaction. It DOES NOT take part or participate in the reaction.