(1)Write the formulas of the reactants on the left. (2)Using charges, put everything on the left together on the right. (3)And then, balance using coefficients!
Sodium reacts with chlorine...
(1) Na + Cl2 --->
Na + Cl2 ---> NaCl
(3) 2Na + Cl2 ---> 2NaCl
Decomposition: (opposite of synthesis)
(1)Write the formulas of the reactant on the left using charges. (2)Take everything on the left apart on the right. (3)And then, balance using coefficients!
H2O ---> H2 + O2
2 H2O ---> 2 H2 + O2
Single Replacement: Someone cutting in on a dance. Look at the what is by itself on the left. It will REPLACE what it is like in the other reactant (couple). Always Use charges and remember diatomics!
Zn + HCl -->
H2 + ZnCl2
Zn + 2 HCl --> H2 + ZnCl2
Double Replacement: Switching Partners. Look at the first partner in each reactant on the left. They will REPLACE each other. Always Use charges and remember diatomics!
KI + Pb(NO3)2 --->
KNO3 + PbI2
2 KI + Pb(NO3)2 ---> 2 KNO3 + PbI2