1. Types of Reactions

2. Generals about writing Equations
Reactants on the left and products on the right
Symbols
Ex: g for gas, l for liquid, s for solid
aq for aqueous (dissolved in water)
Catalyst goes above the arrow KI
Ex H2O2(aq) ---> H2O(l) + O2(g)
Diatomic Molecules - BrINClHOF
Elemental state - Br2I2N2Cl2H2O2F2

3. Chapter 8: Chemical Reactions -- Types of Chemical Reactions --
Classifying reactions
Knowing what kind of reaction is occurring can help you to predict the products of the reaction
Five types of reactions
Synthesis/Combination
Decomposition
Single-replacement
Double-replacement
Combustion
Five major types of reactions
Easier to write the equation if you know the type of reaction

4. 1. Synthesis (Combination)
Two or more substances react to form a single substance
A + B --> AB
Ex) SO3(g) + H2O(l) --> H2SO4(aq)
Usually gives off energy when forming bonds
Examples
2K(s) + Cl2(g)  2KCl(s)
S(s) + O2(g) SO2(g)
2S(s) + 3O2(g)  2SO3(g)
Fe(s) + S(s)  FeS(s)

5. 2Na + Cl2  2NaCl

6. 2. Decomposition
A single compound is broken down into simpler products
AB --> A + B
Requires energy to break chemical bonds (heat, light, electricity)
Examples

7. 2NI3  N2 + 3I2

8. Elephant toothpaste

9. 3. Single Replacement Reactions
One element replaces a second element in a compound
A + BC --> AC + B
Ex) Zn(s) + H2SO4(aq) --> ZnSO4(aq) + H2(g)
A metal may replace a metal or a nonmetal may replace a nonmetal
Activity Series - list of metals in order of decreasing activity
Nonmetals reactivity decreases as you go down the periodic table

10. Activity Series of Metals (Decreasing reactivity)
Activity series of metals A table listing metals in order of decreasing reactivity Metals will displace other metals
Activity Series of Metals
(Decreasing reactivity)
>
Li K Ca Na Mg Al Zn Fe Pb H Cu Hg Ag
Examples
Mg + 2HCl  MgCl2 + H2
Cu + HCl  no reaction
2Fe + 6HCl  2FeCl3 + 3H2

11. 3. Single replacement reactions
Ex) Which element will get kicked out? Hint- figure out which is more reactive- the more reactive one will bond and the less reactive one will be kicked out.
Al(s) + H2SO4(aq) 

12. 3. Single replacement reactions
Ex) Which element will be replaced? (or kicked out?)
Cl2(g) KI(aq) -->
Cu + FeSO4 

13. Fe2O3 + 2Al → 2Fe + Al2O3 Brainiac on Thermite

14. 4. Double Replacement
Exchange of positive ions between two ionic compounds. Just swap the positive ions (the cations) and write the new formula.
A+B- + C+D- --> C+B- + A+D-
Examples
Barium chloride and potassium carbonate solutions react.
BaCl2(aq) + K2CO3(aq) 
BaCl2(aq) + K2CO3(aq)  BaCO3(s) + 2KCl(aq)
BaCO3 is the precipitate.
Sodium hydroxide and lead (II) nitrate solutions react.
NaOH(aq) + Pb(NO3)2(aq) 
2NaOH(aq) + Pb(NO3)2(aq)  2NaNO3(aq) + Pb(OH)2(s)
Pb(OH)2 is the precipitate.
Product usually a gas, precipitate, or molecular compound like water

15. Lead nitrate reacts with Potassium iodide

16. 5. Combustion Reactions
Oxygen reacts with another substance, often producing heat and light
Oxygen (O2) will always be one of your reactants
Often involve hydrocarbons
Compounds of hydrogen and carbon
Combustion of hydrocarbons produces a lot of energy, therefore, hydrocarbons are used as fuels.
Examples: methane, propane, butane, octane

17. 5. Combustion Reactions Two types of combustion 1. Complete combustion
Always produces water and CO2
CxHy + O2(g) --> CO2(g) + H2O(g) + energy
2. Incomplete combustion
Two more products: CO and C
CxHy + O2(g) --> CO2(g) + H2O(g) + CO(g) + C(s) + energy

18. Methane mamba
Let’s try it!