Final answer:
The question revolves around the fundamentals of chemical equations, which include reactants, products, and the conservation of mass during chemical reactions. The states of substances and special conditions can also be represented in these equations.
Step-by-step explanation:
The discussion involves chemical reactions and the notation used to represent them. Reactants are substances that undergo change during a chemical reaction and are displayed on the left side of a chemical equation. The new substances formed are called products and are shown on the right. The equation for the combustion of methane is an example used to illustrate this point.
Chemical equations also demonstrate the law of conservation of mass, as substances that appear as reactants in one part of a multi-step reaction sequence may appear as products in another, allowing them to cancel each other out algebraically when equations are added together. Additional information that can be included in a chemical equation includes the physical states of the reactants and products, designated as (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous, alongside special conditions like temperature.