How to learn a chemical equation numbering
Answers
First, you have to have a good grasp of chemical nomenclature, the naming of compounds given their chemical formula and the determining of chemical formula given the compound name.
Second, for inorganic chemistry, learn to recognize the type of chemical reaction under consideration. There are five basic types of chemical reactions. Their characteristics are given below:
Synthesis: more than one reactant; one product. Example: CaO + CO2 → CaCO3
Decomposition: one reactant; more than one produce. Example: 2H2O2 → O2 + 2H2O
Single replacement: 1 element and 1 compound as reactants; 1 element and one compound as products. Example: Mg + 2HCl → MgCl2 + H2
Double replacement: two compounds as reactants; two compounds as products. Example: NaCl + Pb(NO3)2 → PbCl2 + NaNO3
Combustion: usually considered as a hydrocarbon compound and oxygen as reactants; water and carbon dioxide as products. Example: CH4 + 2O2 → CO2 + 2H2O
Within these reaction types other classes of reactions occur, most notably acid-base neutralization reactions and redox reactions.
The situation is more complex for organic reactions. There aren’t simple formulas for reaction types.