1. What do these two things have in Common? GO 2 Describe and interpret patterns in chemical reactions

2. Guided Question How can you tell when a chemical Reaction or physical reaction has occurred?

3. 2-1 Chemical Reactions Chemical reactions are the changes of matter that occurs when compounds react with each other Reactants- the compounds present when a reaction happens these are what do the reacting these are what do the reacting Product - the compounds created by the reaction these were not present initially these were not present initially

4. ReactantsProducts Ex. In a car, octane (C 8 H 18 ) reacts with oxygen gas (O 2 ) to produce carbon dioxide (CO 2 ), water (H 2 O) and energy Ex. In a car, octane (C 8 H 18 ) reacts with oxygen gas (O 2 ) to produce carbon dioxide (CO 2 ), water (H 2 O) and energy  This can be written in a shorter form as a chemical WORD equation: Octane + Oxygen Carbon Dioxide + Water + energy released  In our equation, the “+” means “and” and the “ “ means “produces”

5. How can you tell a CHEMICAL REACTION happened? Products are different from the reactants! Some clues to look for: Ø Colour change / appearance Ø odour change / released Ø A solid (precipitate) has formed or has a gas been generated. Ø There is a temperature change (heat is absorbed or released) Usually if two or more of these are present, a chemical reaction has occurred

6. Looking back at our octane example, how do you know a chemical reaction occurred?  An odour is given off from burning fuel  A gas is generated (CO 2(g) and H 2 O (g) )  Energy stored in the fuel (octane) has been released, the engine is hotter so a chemical change has taken place.

7. Endothermic & Exothermic Reactions EXOTHERMIC REACTION - energy is released to the environment Energy is given off. Energy is given off. The octane reaction is an exothermic one The octane reaction is an exothermic one C 8 H 18 + O 2 CO 2 + H 2 O + ENERGY

8. ENDOTHERMIC REACTION- When energy is absorbed from the environment ENDOTHERMIC REACTION- When energy is absorbed from the environment Energy is required. Energy is required. Temperature drops Temperature drops With photosynthesis, plants use light energy to produce glucose With photosynthesis, plants use light energy to produce glucose CO 2 + H 2 O + ENERGY C 6 H 12 O 6 + O 2

9. OXYGEN (O 2 ): The breath of Life  A very reactive gas  78.09% of earths atmosphere is O 2(g)  O 2 is a crucial reactant in various types of chemical reactions (you are expected to know all three of these!)

10. If oxygen combines with any other element or compound (fuels such as sugars, octane, natural gas, metals, etc.) the reaction could be: 1) Combustion 2) Corrosion 3) Cellular Respiration

11. 1) COMBUSTION REACTION Combustion is a rapid Chemical reaction with oxygen where a large amount of energy is produced  Complete combustion reactions produce carbon dioxide, water vapour and LOTS of energy  Incomplete combustion reaction involves only the partial burning of a fuel. It will produce carbon monoxide and nitrogen oxides.  CH 4 + 2 O 2 → CO 2 + 2 H 2 O + energy

12. 2) CORROSION Corrosion is a slow Chemical reaction with oxygen where an metal oxide is produced and there is a slow release of energy 2Fe(s) + O 2 (g) + H 2 O(l) Fe(OH) 2 2Fe(s) + O 2 (g) + H 2 O(l) Fe(OH) 2 Ex. A car takes a long time to rust; it does not Happen overnight

13. 3) CELLULAR RESPIRATION Cellular respiration is a chemical reaction using oxygen that happens in the cells of your body Cellular respiration is a chemical reaction using oxygen that happens in the cells of your body  Food ( C 6 H 12 O 6 ) reacts with oxygen O 2 to produce water (H 2 0), carbon dioxide (CO 2 ) and chemcial energy O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2