Writing a balanced ionic equation

When writing an ionic equation, state symbols of the substances must be clearly indicated. Only ionic compounds which are soluble in water (forming aqueous solution) will dissociate into ions in water. Insoluble substance cannot dissociate into ions in water.

Example:

Write the ionic equation for the word equation

Sodium chloride(aq) + silver nitrate(aq) → silver chloride(s) + sodium nitrate(aq)

Solution:

Step 1: Write the equation and balance it if necessary

NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq)

Step 2: Split the ions. (Only compounds that are aqueous are split into ions.)

Na⁺(aq) + Cl^-(aq) + Ag⁺(aq) + NO₃^-(aq) → AgCl(s) + Na⁺(aq) + NO₃^-

Step 3: Cancel out spectator ions. (Spectator ions are ions that remain the same in their original states before and after a chemical reaction.)

Step 4: Write a balanced ionic equation

Ag⁺(aq) + Cl^-(aq) → AgCl(s)

Example:

Write the ionic equation for the word equation

Sodium(s) + hydrochloric acid(aq) -> sodium chloride(aq) + hydrogen(g)

Solution:

Step 1: Write the equation and balance it.

2Na(s) + 2HCl(aq) -> 2NaCl(aq) + H₂(g)

Step 2: Split the ions. (Only compounds that are aqueous are split into ions.)

2Na(s) + 2H⁺(aq) + 2Cl^-(aq) → 2Na⁺(aq) + 2Cl^-(aq) + H₂(g)

Step 3: Cancel out spectator ions. (Spectator ions are ions that remain the same in their original states before and after a chemical reaction.)

Step 4: Write a balanced ionic equation

2Na(s) + 2H⁺(aq) → 2Na⁺(aq) + H₂(g)

The following video shows an example of writing an ionic equation.

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