Net Ionic Equation Calculator

Q: How can I identify spectator ions?

Spectator ions are ions that appear unchanged on both sides of the complete ionic equation . To identify them, write the complete ionic equation , then compare ions on the reactant and product sides. Any ion with the same charge, formula, and coefficient on both sides does not participate in the reaction and can be canceled . Removing these ions reveals the net ionic equation .

Q: What is the HCl + NaOH net ionic equation?

The HCl + NaOH net ionic equation is H + (aq) + OH - (aq) → H 2 O(l) . Both HCl and NaOH fully dissociate in water. The sodium ( Na + ) and chloride ( Cl - ) ions remain unchanged and act as spectator ions , so they’re removed from the complete ionic equation .

Q: How can I write net ionic equation?

You can write a net ionic equation by following these steps: Write the balanced molecular equation . Split all soluble ionic compounds into ions. Keep solids, liquids, and gases intact. Write the complete ionic equation . Identify and cancel spectator ions . Check that mass (number of each type of element) and charge are conserved.

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If you’ve ever wondered what a net ionic equation is and why chemists bother writing reactions this way, Omni’s net ionic equation calculator is here to help. Our smart tool enables you to uncover what is really happening in reactions that occur in aqueous solutions.

By converting reactions into ionic and net ionic equations, it highlights the species that actually react, shows how to identify spectator ions, and reduces the complete ionic equation to a clear, balanced net ionic equation that captures the core of the chemistry. You’ll see how chemists choose which ions to include and how their order is often a matter of convention.

With a bit of practice, net ionic equations will stop feeling like a puzzle 😵, and you’ll be solving them like a pro!

What is a net ionic equation?

A net ionic equation is a chemical equation that shows only the ions and substances that actually participate in a reaction. It’s most commonly used for reactions that take place in an aqueous solution, where dissolved compounds split into charged particles called cations (positive charge) and anions (negative charge).

The physical state of each substance is important: species marked as (aq) can dissociate into ions, while (s), (l), and (g) indicate solids, liquids, or gases that don’t freely move as ions in solution.

For example, soluble salts such as sodium chloride (NaCl) or calcium chloride (CaCl₂) exist in solution as separate ions rather than intact molecules:

\mathrm{NaCl_{(aq)} \rightarrow Na^+ + Cl^-}\\[1em] \mathrm{CaCl_{2(aq)} \rightarrow Ca^{2+} + 2Cl^-}

In the case of CaCl₂, one Ca²⁺ cation is formed together with two Cl^- anions, so the total charge remains balanced.

Strong acids and bases behave similarly: acids like sulfuric acid (H₂SO₄) fully dissociate into hydrogen ions and their corresponding anions, while bases such as sodium hydroxide (NaOH) produce hydroxide ions (OH^-).

\mathrm{H_2SO_{4(aq)} \rightarrow 2H^+ + SO_4^{2-}}\\[1em] \mathrm{NaOH_{(aq)} \rightarrow Na^+ + OH^-}

Note that in sulfuric acid, the SO₄^2- anion has a $−2$ charge, so the acid releases two H⁺ cations to keep the total charge balanced.

Other compounds may remain as neutral molecules or dissociate only partially, depending on their chemical nature.

Ionic and net ionic equations help reveal which species actually react and what truly drives a chemical change. Learning how to write net ionic equations makes it easier to interpret reactions such as precipitation, acid–base neutralization, or gas formation, where only certain ions undergo a real chemical change.

Complete ionic equation vs. net ionic equation

Let’s take a closer look at what really happens in a chemical reaction in aqueous solution, for example, when silver nitrate (AgNO₃) reacts with sodium chloride (NaCl). We begin with the molecular (overall) equation, which shows the compounds as intact formulas:

\begin{gather*} \rm AgNO_{3(aq)} + NaCl_{(aq)} \rightarrow \\[1em] \rm AgCl_{(s)} + NaNO_{3(aq)} \end{gather*}

At this stage, the equation tells us what reacts and what forms, but not how the ions behave in solution. Explore our molarity calculator to analyze reactions in aqueous solutions more deeply.

Next, we rewrite all soluble ionic compounds as their ions, giving the complete ionic equation: it shows every ion present in solution. All substances labeled (aq) dissociate in water, while AgCl is a solid precipitate and doesn’t dissociate:

\mathrm{Ag^+_{(aq)} + NO^-_{3(aq)} + Na^+_{(aq)} + Cl^-_{(aq)} \rightarrow} \\[1em] \mathrm{AgCl_{(s)} + Na^+_{(aq)} + NO^-_{3(aq)}}

Some ions appear unchanged on both sides of the equation: Na⁺, NO₃^-. These ions do not take part in the chemical change and are called spectator ions (read more about what spectator ions are here). We can remove them:

\mathrm{Ag^+_{(aq)} + \cancel{NO^-_{3(aq)}} + \cancel{Na^+_{(aq)}} + Cl^-_{(aq)} \rightarrow} \\[1em] \mathrm{AgCl_{(s)} + \cancel{Na^+_{(aq)}} + \cancel{NO^-_{3(aq)}}}

After canceling the spectator ions, the net ionic equation remains, showing the actual chemical change:

\mathrm{Ag^+_{(aq)} + Cl^-_{(aq)} \rightarrow AgCl_{(s)}}

The net ionic equation shows the actual chemical change: silver and chloride ions combine to form an insoluble AgCl.

A properly balanced net ionic equation conserves both mass and charge. In this case, there is one Ag⁺ and one Cl^- ion on each side, and the total charge is zero on both sides. Because neither atoms nor charge are gained or lost, the net ionic equation is balanced as written.

🙋 Once you know which species actually react in a net ionic equation, the equilibrium constant calculator can show you how far the reaction goes and whether products are strongly favored.

How to find a net ionic equation (step by step)

Based on the example above, here’s a simple algorithm for how to find a net ionic equation (and how to write net ionic equations). We’ll use the reaction between barium chloride (BaCl₂) and sodium sulfate (Na₂SO₄).

Begin with the balanced molecular equation with states:

\quad \begin{gather*} \rm BaCl_{2(aq)} + Na_2SO_{4(aq)} \rightarrow \\[1em] \rm BaSO_{4(s)} + 2NaCl_{(aq)} \end{gather*}

Now split aqueous ionic compounds into their ions. The solid stays intact:
- BaCl₂ dissociates into Ba²⁺ and 2Cl^-;
- Na₂SO₄ dissociates into 2Na⁺ and SO₄^2-; and
- 2NaCl dissociates into 2Na⁺ and 2Cl^-.
Write the complete ionic equation, presenting all the ions in the solution.
Identify and cancel spectator ions. The core of how to identify spectator ions is that they appear unchanged on both sides with the same coefficient.
- 2Cl^- — Appears on both sides → spectator ion; and
- 2Na⁺ — Appears on both sides → spectator ion.
After removing spectator ions, combine the ions into the complete, balanced net ionic equation, making sure that both mass and charge are conserved on each side:

\quad\mathrm{Ba^{2+}_{(aq)} + SO^{2-}_{4(aq)} \rightarrow BaSO_{4(s)}}

Check what the net ionic equation tells you. Barium ions and sulfate ions combine to form solid BaSO₄, a precipitate that leaves the solution.

A net ionic equation example explained

Below are several net ionic equation examples that apply the method described above and show how different compounds behave in aqueous solution. In each case, the complete ionic equation is simplified by identifying and removing spectator ions, leaving only the species that actually react in aqueous solution.

Example 1: Acid–base neutralization (strong acid + strong base)

Molecular equation:

\hspace{-0.8em} \rm HCl_{(aq)}+NaOH_{(aq)} \rightarrow NaCl_{(aq)}+H_2​O_{(l)}

Complete ionic equation:

\begin{gather*}\rm H^+_{(aq)}+Cl^-_{(aq)}+Na^+_{(aq)}+OH^-_{(aq)} \rightarrow \\[1em] \rm Na^+_{(aq)}+Cl^-_{(aq)}+H_2O_{(l)} \end{gather*}

Net ionic equation:

\rm H^+_{(aq)} + OH^-_{(aq)} \rightarrow H_2O_{(l)}

Example 2: Acid–base neutralization (weak acid + strong base)

Molecular equation:

\begin{gather*} \rm HNO_{2(aq)}+KOH_{(aq)} \rightarrow \\[1em] \rm KNO_{2(aq)}+H_2​O_{(l)} \end{gather*}

Because $\rm HNO_2$ is a weak acid, it doesn’t fully dissociate in water. Check our pH calculator to understand acid–base strength.

Complete ionic equation:

\begin{gather*} \rm HNO_{2(aq)}+K^+_{(aq)}+OH^-_{(aq)} \rightarrow \\[1em] \rm K^+_{(aq)}+NO^-_{2(aq)}+H_2O_{(l)} \end{gather*}

Net ionic equation:

\begin{gather*} \rm HNO_{2(aq)}+OH^-_{(aq)} \rightarrow \\[1em] \rm NO^-_{2(aq)}+H_2O_{(l)} \end{gather*}

Example 3: Single-displacement (redox) reaction

Molecular equation:

\hspace{-0.8em} \rm Zn_{(s)}+CuSO_{4(aq)} \rightarrow ZnSO_{4(aq)}+Cu_{(s)}

Complete ionic equation:

\begin{gather*} \rm Zn_{(s)}+Cu^{2+}_{(aq)}+SO^{2-}_{4(aq)} \rightarrow \\[1em] \rm Zn^{2+}_{(aq)}+SO^{2-}_{4(aq)}+Cu{(s)} \end{gather*}

Net ionic equation:

\rm Zn_{(s)}+Cu^{2+}_{(aq)} \rightarrow Zn^{2+}_{(aq)}+Cu{(s)}

How to use net ionic equation calculator

Using our net ionic equation calculator (or net ionic chemical equation calculator) is pretty simple:

Enter the left and right sides of your equation. The equation does not need to be balanced.
Type correct chemical formulas (for example, AgNO3, not AgNo3).
Use + to separate multiple compounds on each side.
Add state symbols: (aq), (s), (l), (g). If no state is provided, the net ionic equation calculator will treat the compound as aqueous (aq).
Alternatively, select an example reaction from the list below the equation field (if your problem is included).
The net ionic equation calculator will instantly balance the reaction, rewrite the complete ionic equation, identify spectator ions, and display the net ionic equation.

FAQs

How can I identify spectator ions?

Spectator ions are ions that appear unchanged on both sides of the complete ionic equation. To identify them, write the complete ionic equation, then compare ions on the reactant and product sides. Any ion with the same charge, formula, and coefficient on both sides does not participate in the reaction and can be canceled. Removing these ions reveals the net ionic equation.

What is the HCl + NaOH net ionic equation?

The HCl + NaOH net ionic equation is H⁺(aq) + OH^-(aq) → H₂O(l).

Both HCl and NaOH fully dissociate in water. The sodium (Na⁺) and chloride (Cl^-) ions remain unchanged and act as spectator ions, so they’re removed from the complete ionic equation.

Why do we use net ionic equations?

We use net ionic equations to focus on the actual chemical change occurring in a reaction. By removing spectator ions, a net ionic equation shows only the species that truly react. This procedure makes reactions in aqueous solution easier to understand, especially for those reactions where many dissolved ions do not participate directly.

How can I write net ionic equation?

You can write a net ionic equation by following these steps:

Write the balanced molecular equation.
Split all soluble ionic compounds into ions.
Keep solids, liquids, and gases intact.
Write the complete ionic equation.
Identify and cancel spectator ions.
Check that mass (number of each type of element) and charge are conserved.