Chemical equations are symbolic representations of chemical reactions. They show the reactants on the left side and products on the right side, connected by an arrow. For example, hydrogen gas reacts with oxygen gas to form water.
In our example reaction, we need to identify the reactants and products. The reactants are hydrogen gas and oxygen gas, shown on the left side. The product is water, shown on the right side. Reactants are consumed during the reaction while products are formed.
The first step is to write the unbalanced chemical equation using the correct chemical formulas. We write hydrogen gas as H2, oxygen gas as O2, and water as H2O. At this stage, we don't worry about balancing - we just focus on getting the correct formulas for all reactants and products.
Now we balance the equation by adding coefficients. First, balance oxygen: there are 2 oxygen atoms on the left and 1 on the right, so we add coefficient 2 to water. Next, balance hydrogen: now there are 4 hydrogen atoms on the right, so we add coefficient 2 to hydrogen gas. Let's verify: left side has 4 hydrogen and 2 oxygen atoms, right side has 4 hydrogen and 2 oxygen atoms. The equation is now balanced.
Here is our final balanced chemical equation: 2H₂ + O₂ → 2H₂O. This means 2 molecules of hydrogen gas react with 1 molecule of oxygen gas to produce 2 molecules of water. The equation is balanced because mass is conserved - we have 4 hydrogen atoms and 2 oxygen atoms on both sides. This balanced equation follows the fundamental law of conservation of mass in chemical reactions.