Subsection 8.3.5 Chemical Equations
A chemical equation is a representation of a chemical reaction using symbols and formulas to show the reactants and products involved in the reaction. Chemical equations are written in a balanced form, meaning that the number of atoms of each element is the same on both sides of the equation. This is because the law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction, only rearranged. The general form of a chemical equation is: Reactants → Products For example, the chemical equation for the reaction between hydrogen gas and oxygen gas to form water is:
\begin{equation*}
2H_2 + O_2 \rightarrow 2H_2O
\end{equation*}
This equation shows that two molecules of hydrogen gas \((H_2)\) react with one molecule of oxygen gas \((O_2)\) to form two molecules of water \((H_2O)\text{.}\) The equation is balanced because there are four hydrogen atoms and two oxygen atoms on both sides of the equation.
Chemical equations can also include coefficients, which are used to balance the equation. Coefficients are numbers placed in front of the chemical formulas to indicate the number of molecules or atoms involved in the reaction. For example, the balanced equation for the reaction between nitrogen gas and hydrogen gas to form ammonia is:
\begin{equation*}
N_2 + 3H_2 \rightarrow 2NH_3
\end{equation*}
In this equation, a coefficient of 3 is placed in front of the \((H_2)\) to balance the number of hydrogen atoms on both sides of the equation.
