Learn: Word equations and balanced symbol equations (with state symbols)

Welcome!Welcome! Today, we’ll build on your knowledge of chemical formulae to explore word equations and balanced symbol equations. These are essential tools for describing chemical reactions clearly and accurately. Let’s get started!

What are word equations?A word equation is a simple way to represent a chemical reaction using the names of the reactants and products. It shows what substances react together and what new substances are formed.For example, the reaction of hydrogen with oxygen to form water can be written as: Hydrogen + Oxygen → Water. This helps us understand what happens in a reaction without using chemical symbols.

What are balanced symbol equations?A balanced symbol equation uses chemical symbols and formulas to represent a reaction. It shows the number of atoms of each element involved in the reaction and ensures the principle of conservation of mass is followed.For example: 2H₂ + O₂ → 2H₂O. Here, the number of atoms of hydrogen and oxygen is the same on both sides of the equation.

Why do we balance equations?In all chemical reactions, the law of conservation of mass applies. This means that atoms cannot be created or destroyed, only rearranged. Balancing equations ensures the same number of atoms are present on both sides of the equation.It helps chemists understand the exact amounts of substances needed and produced in a reaction.

What are state symbols?State symbols tell you the physical state of each substance in a chemical reaction. They are written as small letters in parentheses after the chemical formula.Common state symbols include: (s) for solids, (l) for liquids, (g) for gases, and (aq) for substances dissolved in water (aqueous).

Steps to balance a chemical equationTo balance a chemical equation:Write the formulas for reactants and products.Count the number of atoms for each element on both sides.Add coefficients (numbers in front of formulas) to balance the atoms.Check your work to ensure the equation is balanced.

Example of balancing an equationLet’s balance this equation: H₂ + O₂ → H₂O. On the left, we have 2 hydrogen atoms and 2 oxygen atoms. On the right, there are 2 hydrogen atoms and only 1 oxygen atom.To balance, we add a coefficient of 2 in front of H₂O: 2H₂ + O₂ → 2H₂O. Now, there are 4 hydrogen atoms and 2 oxygen atoms on each side.

Review Time!Great work! We've covered word equations, balanced symbol equations, and state symbols. Now it’s time to test your understanding with a few review questions.