1. Types of Reactions Synthesis Decomposition Single Replacement
Double Replacement
Combustion

2. Synthesis
Two or more substances combine to make a more complex substance
A X  AX

3. Decomposition A compound breaks down into simpler substances.
AX---- A + X

4. Single Replacement
When 1 element replaces another element in a compound.
AX + B ---- AB + X or
A + XB ---- AX + B

5. Double Replacement
When 2 different atoms in 2 different compounds trade places.
AX + BY ----- AY + BX

6. Combustion
where a compound and an oxidant is reacted to produce heat, water and sometimes a new product.
CH4 + 2 O2 → CO2 + 2 H2O + heat

7. Solve the sample problems
Zn HCl-- ZnCl H2
CaCo3 -- CaO CO2
Au O2 -- Au2O3
Pb(NO3) KI ---- PbI KNO3
MgCO HCl - MgCl H2O + CO2