ionic equation_theclassroom

In this short post, I will share with you how you can apply these 4 simple steps to solve/write almost ANY ionic equation! That’s like a F.R.E.E [2 marks] in the bag!

How To Write An Ionic Equation In 4 Simple Steps

  1. Write a balanced chemical equation for the reaction
  2. Fill in the state symbols (You need to be familiar with the solubility table to get this part right)
  3. Split all aqueous substances (Exception of halogens during displacement)
  4. Cancel spectator ions (ions that remain unchanged on the LHS and RHS of the chemical equation)


Here’s 2 examples to show you how its done!

Example 1.

Write an ionic equation for the reaction between sulfuric acid and magnesium carbonate.

    1. Step 1: H2SO4 + MgCO3 –> MgSO4 + CO2 + H2O
    2. Step 2: H2SO4 (aq) + MgCO3 (s)  –> MgSO4(aq) + CO2(g) + H2O(l)
    3. Step 3: 2H+ (aq)  +  SO42- (aq)  +  MgCO3(s)  –>  Mg2+(aq)  +  SO42-(aq)  + CO2(g)  + H2O (l)
    4. Step 4: 2H+ (aq)  +  SO42- (aq)  +  MgCO3(s)  –>  Mg2+(aq)  +  SO42-(aq)  + CO2(g)  + H2O (l)


2H+ (aq)  +  MgCO3(s)  –>  Mg2+(aq)  + CO2(g)  + H2O (l)


Example 2.

Write an ionic equation when aqueous chlorine reacts with potassium bromide.

    1. Step 1  : Cl2 + 2KBr –>  2KCl  + Br2
    2. Step 2: Cl2 (aq) + 2KBr (aq)  –>  2KCl (aq)  + Br2 (aq)
    3. Step 3: Cl2 (aq) + 2K+ (aq) +  2Br  (aq)  –>  2K+(aq)  +  2Cl (aq)  +  Br(aq)
    4. Step 4: Cl2 (aq) + 2K+ (aq) +  2Br  (aq)  –>  2K+(aq)  +  2Cl (aq)  +  Br(aq)


Cl2 (aq) +  2Br  (aq)  –>   2Cl (aq)  +  Br(aq)  [Recall: Although halogens are in aq. state, they do not split to form ions!]

I hope this short post has helped you to recall the basics of Redox. If you found it useful, feel free to share this with your friends!

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