Counting the atoms in each substance in the reactants and products is a step in which one of the following?

A. Balancing a chemical equation

B. Determining how long a chemical reaction will take

C. Duplicating a chemical equation

D. Writing a chemical equation using formulas and symbols

The answer is letter A.

Counting the atoms in each substance in the reactants and the products is a step to balancing a chemical equation. Chemical equations need to be balanced so that they follow the law of conservation of mass (matter can be changed from one form to another but the mass remains constant). Usually balancing equations require a process of trial and error to get the number of atoms of elements in the reactants side to equal the products side.