Question

how to write a chemical equation for any chemical reaction

Answer 1

An equation can be used to describe a physical reaction, which involves a change of states. For example, melting, sublimation, evaporation, and condensation can be represented as follow. In these equations, (s) stands for solid, (l) for liquid (l), and (g) for gas,

H2O(s) ® H2O(l) . . . melting
H2O(s) ® H2O(g) . . . sublimation
C2H5OH(l) ® C2H5OH(g) . . . evaporation
NH3(g) ® NH3(l) . . . condensation
In these changes, no chemical bonds are broken or formed, and the molecular identities of the substances have not changed.