Chapter 8- Writing Chemical Equations

• In order to represent a chemical reaction, we use chemical and word equations.
• An example of a word equation is: magnesium + chlorine → magnesium chloride
• An example of a chemical equation is: Mg + Cl2 → MgCl2
• It is necessary for the number of atoms to be equal on both sides of the equation. Therefore, sometimes there Is a need to balance chemical equations.

STEPS TO WRITING A BALANCED EQUATION

1. Write down the formulae of reactants and products with ‘+’ between each element and an arrow between the reactant and product side.
2. Check the number of atoms of each element on both sides. If it is not balanced, proceed to balance it.
3. Balance the formulae by placing numbers before different substances until there are the same number of atoms on each side.
4. Write state symbols.

• Ionic equations are simplified chemical equations for substances soluble in water.
• Spectator ions are ions that take no part in the chemical reaction and can be canceled on both sides of the equation.

STEPS TO WRITING IONIC EQUATIONS

1. Write a balanced chemical equation, including the state symbols.
2. Rewrite the substances that are in aqueous state in the form of ions. Substances in any other state are not broken into ions.
3. Cancel out spectator ions.
4. Rewrite the equation with the remaining substances.