1. Types of Reactions
Science 10

2. Chemical Reactions can be:
Exothermic: Reactions that release energy
Example: A chemical explosion
Endothermic: A reaction that needs energy in order for the reaction to take place.
Example: Cooking a pancake over a hot stove.

3. To break chemical bonds, energy is needed.
Example: thermal energy + 2H2O → 2H2 + O2
There is always a release of energy when reactants are added together.
Example: 2H2 + O2 → 2H2O + thermal energy

4. Examples … vaporization of water condensation of water ice melting
rusting of iron
photosynthesis
cellular respiration
cooking food
an explosion
Endothermic
Exothermic
Examples …

5. Endothermique ou Exothermique?
1. Melting ice
endothermic
2. A mixture of H2 and Cl2 that explode after they are mixed together
Exothermic
3. Na + Cl2 → NaCl + thermal energy
exothermic
4. thermal energy + H2O → H2 + O2

6. Indicate whether each of the following are exothermic or endothermic reactions.  
Melting Ice
Sulphuric acid added to water increases the temperature of the solution.   
A mixture of hydrogen and chlorine gas explodes if it is mixed together.  
Cooking a pancake over a hot stove.  
Thermal energy   + NO2   →  N2  +  O2      
Na  +  Cl2  →  NaCl  +  thermal energy