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
- Write a balanced chemical equation for the reaction
- Fill in the state symbols (You need to be familiar with the solubility table to get this part right)
- Split all aqueous substances (Exception of halogens during displacement)
- Cancel spectator ions (ions that remain unchanged on the LHS and RHS of the chemical equation)
Viola!
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.
- Step 1: H2SO4 + MgCO3 –> MgSO4 + CO2 + H2O
- Step 2: H2SO4 (aq) + MgCO3 (s) ?–> MgSO4(aq) + CO2(g) + H2O(l)
- Step 3: 2H+ (aq) ?+ ?SO42- (aq) ?+ ?MgCO3(s) ?–> ?Mg2+(aq) ?+ ?SO42-(aq) ?+ CO2(g) ?+ H2O (l)
- Step 4:?2H+?(aq) ?+
?SO42-?(aq)?+ ?MgCO3(s) ?–> ?Mg2+(aq) ?+ ?SO42-(aq)?+ CO2(g) ?+ H2O (l)
Viola!
2H+?(aq) ?+ ?MgCO3(s) ?–> ?Mg2+(aq) ?+ CO2(g) ?+ H2O (l)
Example 2.
Write an ionic equation when aqueous chlorine reacts with potassium bromide.
- Step 1 ?: Cl2 + 2KBr –> ?2KCl ?+ Br2
- Step 2:?Cl2?(aq) + 2KBr (aq) ?–> ?2KCl (aq) ?+ Br2 (aq)
- Step 3:?Cl2?(aq) + 2K+ (aq) + ?2Br– ?(aq) ?–> ?2K+(aq) ?+ ?2Cl– (aq) ?+ ?Br2?(aq)
- Step 4:?Cl2?(aq) +
2K+?(aq)+ ?2Br–??(aq) ?–> ?2K+(aq)?+ ?2Cl–?(aq) ?+ ?Br2?(aq)
Viola!
Cl2?(aq) + ?2Br–??(aq) ?–> ??2Cl–?(aq) ?+ ?Br2?(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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