Question

write the formula for how a chemical reaction happens.

Explanation:

A chemical reaction involves reactants being converted into products, with coefficients balancing the number of atoms on each side to follow the law of conservation of mass. The general formula represents this core process.

Answer:

General formula for a chemical reaction:
$$\text{Reactants} \xrightarrow{\text{Conditions}} \text{Products}$$
For a balanced example (e.g., combustion of hydrogen):
$$2\text{H}_2 + \text{O}_2 \xrightarrow{\text{Ignition}} 2\text{H}_2\text{O}$$