Question

How one reaction happens? What is the process to write any reaction?

Answer 1

You use a chemical equation to represent a chemical reaction.

Explanation:

For example:

`2H_2+O_2→2H_2O`

The first 2 is called a coefficient.

The coefficient is the number before a chemical equation/formula that shows how many molecules are involved in a chemical reaction.
So for example here we have 2H or 2 hydrogen molecules.

The subscript, the small number on the bottom right of the H, indicates the number of atoms of the element immediately before the subscript. (If there is no subscript there is only 1 atom of that element.)

So we known there is 2 hydrogen molecules, and each molecule is made up of 2 atoms.

`0_2` is one oxygen molecule that contains two oxygen atoms.

When `2H_2` combines with `O_2` it produces (→) `2H_2O`

The (g) indicates the state of matter, which is gas in this picture.