In a chemical reaction, reactants combine to form products. A chemical reaction is represented by a chemical equation. A net ionic equation is a chemical equation for a reaction that lists only those species which participate in the reaction. It omits spectator ions, which go through the reaction unchanged. The net ionic equations show the actual chemical change that takes place in a reaction.
Introduction of the concept
A chemical equation that only shows the ions, elements, and compounds which are directly involved in a chemical reaction is known as net ionic equation.
The ions that are found unchanged, before and after the chemical reaction and don’t take part in overall chemical reactions are called spectator ions. They just watch the show and do not do anything, making them spectators.
Steps to Write Net Ionic Equation
- Write down the balanced chemical equation.
- Write the states ( s, ℓ, g, and aq ) for each substance. (s) for solids, (ℓ) for liquids, (g) for gases, and (aq) for aqueous solutions.
- Split the strong electrolyte into respective ions.
- Cancel out the spectator ions which are present on both sides of the chemical equation.
- Write down the remaining species as net ionic equation.
Examples of Net Ionic Equations (Problems)
Example 1: Write net ionic equations of NH3 + H2SO4 → (NH4)2SO4
Step1. Write down the balanced chemical equation.
2NH3 + H2SO4 → (NH4)2SO4
Step2. Write the states ( s, l, g and aq ) for each substance.
2NH3(aq) + H2SO4(aq) → (NH4)2SO4(aq)
Step3. Split the strong electrolyte into respective ions.
2NH3(aq) + 2H+(aq) + SO-24(aq) → 2NH+4(aq) + SO-24(aq)
Step4. Cancel out the spectator ions, present on both sides of a chemical equation.
2NH3(aq)+ 2H+(aq)+ SO-24(aq) → 2NH+4(aq)+ SO-24(aq)
Step5. Write down the remaining substances as a net ionic equation.
2NH3(aq) + 2H+(aq) → 2NH+4(aq)
Example 2: Write net ionic equations of AgNO3 + NaCl → NaNO3 + AgCl
Step1. Write down the balanced chemical equation.
AgNO3 + NaCl → NaNO3 + AgCl
Step2. Write the states ( s, l, g and aq ) for each substance.
AgNO3(aq) + NaCl(aq) → NaNO3(aq) + AgCl(s)
Step3. Split the strong electrolyte into respective ions.
Ag+(aq) + NO–3(aq) + Na+(aq) + Cl–(aq) → Na+(aq) + NO–3(aq) + AgCl(s)
Step4. Cancel out the spectator ions which are present on both sides of a chemical equation.
Ag+(aq) + NO–3(aq) + Na+(aq) + Cl–(aq) → Na+(aq) + NO–3(aq) + AgCl(s)
Step5. Write down the remaining substances as net ionic equation.
Ag+(aq) + Cl–(aq) → AgCl(s)
Example 3: Write net ionic equations of (NH4)2CO3 + Al(NO3)3 → NH4NO3 + Al2(CO3)3
Step1. Write down the balanced chemical equation.
3(NH4)2CO3 + 2Al(NO3)3 → 6NH4NO3 + Al2(CO3)3
Step2. Write the states ( s, l, g and aq ) for each substance.
3(NH4)2CO3(aq) + 2Al(NO3)3(aq) → 6NH4NO3(aq) + Al2(CO3)3 (s)
Step3. Split the strong electrolyte into respective ions.
6NH+4(aq) + 3CO3-2(aq) + 2Al+3(aq) + 6NO–3(aq) → 6NH+4(aq)+6NO–3(aq) + Al2(CO3)3 (s)
Step4. Cancel out the spectator ions which are present on both sides of a chemical equation.
6NH+4(aq) + 3CO3-2(aq) + 2Al+3(aq) + 6NO–3(aq) → 6NH4+(aq) + 6NO–3(aq)+ Al2(CO3)3 (s)
Step5. Write down the remaining substances as net ionic equation.
3CO3-2 (aq) + 2Al+3(aq) → Al2(CO3)3 (s)
Related Articles
- Solubility Rules
- Solubility Product (Ksp); Definition, Applications
- Why must chemical equations be balanced?
Key Takeaway(s) for Net Ionic Equations
Concept Bergs
What is the net ionic equation?
A chemical equation that only shows the ions, elements, and compounds which are directly involved in a chemical reaction is called a net ionic equation.
What is a net ionic equation? Give an example.
An equation representing the net takeout of a chemical reaction is termed the net ionic equation. For example, for a reaction;
HCl + NaOH → NaCl + H2O
The net ionic equation for this reaction is;
H+(aq) + OH–(aq) → H2O
What are ionic and net ionic equations?
Ionic equations show the complete chemical reaction, including the spectator ions involved.
AgNO3 + NaCl → NaNO3 + AgCl
The ionic equation for this reaction is;
Ag+(aq)+NO–3(aq) + Na+(aq) + Cl––(aq) → Na+(aq)+NO–3(aq)+AgCl(s)
Net ionic equations show only the species participating in the reaction, without the spectator ions.
The net ionic equation for the above reaction would therefore be;
Ag+(aq) + Cl–(aq) → AgCl(s)
What is the net ionic equation of NaOH and HCl?
For HCl + NaOH → NaCl + H2O, the net ionic equation is;
H+(aq) + OH–(aq) → H2O
Why are net ionic equations used?
Net ionic equations are used to show the participating ions or active species in a chemical reaction, excluding the spectator ions. They are useful for simplifying the overall reaction and for focusing on the chemical species that are responsible for the chemical change.
References
- Essential of Physical Chemistry by B.S. Bahl, Arun Bahl, G.D. Tuli, and S Chand
- Chemistry: The Molecular Science By John Olmsted, Gregory M. Williams
