The coefficient in a chemical formula tells you the mole ratio between the reactants and products in a chemical reaction.

Here's how it works:

* Coefficients: The numbers in front of each chemical formula in a balanced equation are called coefficients. They represent the relative number of moles of each substance involved in the reaction.

* Mole Ratio: The coefficients provide a direct comparison of the number of moles of each reactant and product.

Example:

Consider the balanced equation for the combustion of methane:

CH₄ + 2O₂ → CO₂ + 2H₂O

* Coefficient of CH₄: 1

* Coefficient of O₂: 2

* Coefficient of CO₂: 1

* Coefficient of H₂O: 2

This tells us that:

* 1 mole of methane (CH₄) reacts with 2 moles of oxygen (O₂)

* 1 mole of methane (CH₄) produces 1 mole of carbon dioxide (CO₂) and 2 moles of water (H₂O)

Key point: The mole ratio is crucial for understanding the stoichiometry of chemical reactions and for performing calculations involving quantities of reactants and products.