1. Types of Chemical Reactions

2. Chemical Reaction Types based on ∆ Energy
Exothermic
Endothermic

3. 1) Exothermic – energy comes out of rxn (rxn gives off energy)
Energy contained in chemical bonds is given off when
the bonds are broken
Forms of energy given off….
Heat, light, sound, electricity

4. 2) Endothermic – energy goes into rxn. (rxn takes in energy)
Absorbs energy and uses it to make chemical bonds
Feels cold

5. Chemical Rxn Types Based on Products
1) Synthesis rxn – (combination rxn)
Put small molecules together to make larger molecules
Look for : more reactants than products
Example: C + O2  CO2

6. 2) Decomposition rxn –
Take apart large molecules to get smaller molecules
Look for : more products than reactants
Example : H2CO3  H2O + CO2

7. 3) Single Replacement rxn –
A single pure element takes the place of a different pure element in a compound
Look for : pure element as reactant and a different pure element as a product
Example : Zn + H2(SO4)  H2(SO4) + H2

8. 3) Double Replacement rxn –
Two compounds trade cations
Look for : 2 compounds as reactants and
2 different compounds as products
Example : Mg(CO3) + HCl  MgCl + H(CO3)

9. Another example
KCl + Pb(NO3) -->
K(NO3) + PbCl

10. A Special Double Replacement Rxn = Neutralization Reactions
Acid + Base  Salt + H2O
Reactants : Acid + Base
Products : Salt + H2O