So there are basically five types of chemical reactions which have their general formulas.
They are:
1. Combination reaction
General formula : A+B = AB
2. Decomposition reaction
General formula: AB = A+B
3. Single displacement reaction
General formula: AB+C = CB + A
4. Double displacement reaction
General formula: AB+CD = CB+AD
5. Acid-base reaction
General formula: A+B = S+W
You should check and compare with examples.