Net Ionic Equation Calculator

Choose any two aqueous reagents and see the balanced molecular, complete ionic and net ionic equations, along with the spectator ions and the solubility rule behind the result.

⚗️ Net Ionic Equation Calculator
First aqueous reagent
Second aqueous reagent
Reaction type
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Driving force
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Spectator ions
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⚗️ What is a Net Ionic Equation?

A net ionic equation is a chemical equation stripped down to only the species that genuinely change during a reaction. When two solutions of ionic compounds are mixed, most of the dissolved ions simply drift past one another and end the experiment exactly as they began. Writing them into the equation adds clutter without adding chemistry. Removing them leaves a compact statement of what actually happened, which is why net ionic equations are the standard way to describe precipitation, neutralisation and gas-forming reactions in every general chemistry course.

Getting there takes three stages. The molecular equation writes every compound as a neutral formula unit, balanced as usual. The complete ionic equation then splits each dissolved strong electrolyte into the separate ions it really forms in water, while leaving solids, liquids, gases and weak electrolytes intact. Finally, any ion appearing identically on both sides is cancelled as a spectator ion, and the remaining coefficients are reduced to their lowest whole-number ratio. For silver nitrate reacting with sodium chloride, that sequence takes AgNO3 (aq) + NaCl (aq) giving AgCl (s) + NaNO3 (aq), through a four-ion complete ionic equation, down to the single line Ag+ (aq) + Cl- (aq) giving AgCl (s).

The step that trips people up is deciding a state. Whether a product precipitates is not a matter of judgement, it is read off the solubility rules, and one misapplied rule changes the entire answer. A second frequent error is splitting things that should stay whole. Acetic acid is aqueous but weak, so it is written as HC2H3O2 (aq) and never as separate ions. Water is a liquid and always stays as H2O (l). A third error is forgetting that if both possible products are soluble, nothing at all happens: the equation cancels completely and the honest answer is that there is no reaction.

This calculator removes the guesswork. Choose any two of the 35 water-soluble reagents in the pickers, which include ordinary salts, the strong acids HCl, HNO3 and H2SO4, and the strong bases NaOH, KOH and Ba(OH)2. The calculator swaps the partners, balances the molecular equation with whole-number coefficients, applies the solubility rules to assign a state to each product, builds the complete ionic equation, cancels the spectators and reduces what remains. It also names the exact rule used for every product, so the answer is something you can check and learn from rather than just copy.

📐 Formula

AB (aq) + CD (aq)  →  AD + CB
A, C = the two cations, which exchange partners in a double displacement reaction
B, D = the two anions
Each product formula is built by criss-crossing the ion charges and reducing the subscripts to their lowest ratio
Example: Ca2+ with PO43− gives Ca3(PO4)2
Complete ionic  −  spectator ions  =  net ionic
Split only soluble ionic compounds, strong acids and strong bases into ions
Keep whole every solid (s), liquid (l), gas (g) and weak electrolyte
Cancel any ion with the same formula and the same coefficient on both sides
Example: Ag+ + NO3− + Na+ + Cl− → AgCl (s) + Na+ + NO3− reduces to Ag+ + Cl− → AgCl (s)
Solubility rules, applied in order 1 to 6
1. All Group 1 and ammonium salts are soluble
2. All nitrates and acetates are soluble
3. Chlorides, bromides and iodides are soluble except Ag+, Pb2+ and Hg22+
4. Sulfates are soluble except Ba2+, Pb2+, Ca2+, Sr2+ and Ag+
5. Hydroxides are insoluble except Group 1, ammonium and Ba2+
6. Carbonates, phosphates and sulfides are insoluble except Group 1 and ammonium

📖 How to Use This Calculator

Steps

1
Select the first aqueous reagent — Pick a reagent from the first dropdown. Every entry in the list is water soluble, so both starting solutions are genuinely aqueous.
2
Select the second aqueous reagent — Pick a different reagent from the second dropdown. The calculator swaps the partners to form the two possible products.
3
Read the three equations — The results table shows the balanced molecular equation, the complete ionic equation with every strong electrolyte split into ions, and the net ionic equation with spectators removed.
4
Check the spectator ions and the rule applied — The species table lists every ion with its state and whether it takes part, and the step notes name the exact solubility rule that decided each product's state.

💡 Example Calculations

Example 1 — Silver nitrate with sodium chloride

The classic chloride test: a white curdy precipitate of silver chloride

1
Swap the partners: AgNO3 + NaCl gives AgCl and NaNO3. Both reactants are 1 to 1 salts, so no coefficients are needed.
2
Rule 3 makes AgCl insoluble, so it is a solid. Rule 2 makes NaNO3 soluble, so it stays aqueous.
3
Complete ionic: Ag+ + NO3− + Na+ + Cl− → AgCl (s) + Na+ + NO3−.
4
Na+ and NO3− appear unchanged on both sides, so they are spectators and cancel.
Net ionic = Ag+ (aq) + Cl− (aq) → AgCl (s), spectators Na+ and NO3−
Try this example →

Example 2 — Lead(II) nitrate with potassium iodide

The golden rain demonstration, and a case that needs coefficients

1
Pb2+ needs two iodides, so the balanced molecular equation is Pb(NO3)2 + 2 KI → PbI2 + 2 KNO3.
2
Rule 3 makes PbI2 insoluble, giving the bright yellow solid, while rule 2 keeps KNO3 in solution.
3
Complete ionic: Pb2+ + 2 NO3− + 2 K+ + 2 I− → PbI2 (s) + 2 K+ + 2 NO3−.
4
Cancelling 2 K+ and 2 NO3− leaves a charge balance of +2 and −2 on the left against a neutral solid on the right.
Net ionic = Pb2+ (aq) + 2 I− (aq) → PbI2 (s), spectators K+ and NO3−
Try this example →

Example 3 — Hydrochloric acid with sodium hydroxide

Strong acid plus strong base, where water is the driving force

1
Swapping partners gives HOH, that is water, plus sodium chloride: HCl + NaOH → H2O + NaCl.
2
Water is a liquid and is never split. NaCl is soluble by rule 1, so it dissociates fully.
3
Complete ionic: H+ + Cl− + Na+ + OH− → H2O (l) + Na+ + Cl−.
4
Sodium and chloride cancel, leaving the equation that describes every strong acid and strong base neutralisation.
Net ionic = H+ (aq) + OH− (aq) → H2O (l), spectators Na+ and Cl−
Try this example →

Example 4 — Hydrochloric acid with sodium carbonate

Fizzing limescale removal, where carbonic acid decomposes to gas

1
Balancing the swap gives 2 HCl + Na2CO3 → H2CO3 + 2 NaCl.
2
Carbonic acid is unstable and decomposes at once, so the products are written H2O (l) + CO2 (g) instead.
3
Complete ionic: 2 H+ + 2 Cl− + 2 Na+ + CO32− → H2O (l) + CO2 (g) + 2 Na+ + 2 Cl−.
4
The escaping carbon dioxide is what pulls the reaction to completion, which is why the mixture fizzes.
Net ionic = 2 H+ (aq) + CO32− (aq) → H2O (l) + CO2 (g), spectators Na+ and Cl−
Try this example →

Example 5 — Sodium phosphate with calcium chloride

Phosphate removal in water treatment, with larger coefficients

1
Ca2+ with PO43− criss-crosses to Ca3(PO4)2, so the molecular equation balances as 2 Na3PO4 + 3 CaCl2 → 6 NaCl + Ca3(PO4)2.
2
Rule 6 makes calcium phosphate insoluble, so it drops out as a solid, while rule 1 keeps sodium chloride dissolved.
3
Complete ionic: 6 Na+ + 2 PO43− + 3 Ca2+ + 6 Cl− → 6 Na+ + 6 Cl− + Ca3(PO4)2 (s).
4
All six sodium and six chloride ions cancel, and the surviving charges balance at +6 against −6.
Net ionic = 3 Ca2+ (aq) + 2 PO43− (aq) → Ca3(PO4)2 (s), spectators Na+ and Cl−
Try this example →

❓ Frequently Asked Questions

What is a net ionic equation?+
A net ionic equation shows only the species that genuinely change, with every spectator ion removed. For silver nitrate and sodium chloride the molecular equation is AgNO3 + NaCl → AgCl + NaNO3, but the net ionic equation is simply Ag+ (aq) + Cl− (aq) → AgCl (s), because sodium and nitrate are unchanged on both sides.
What exactly is a spectator ion?+
A spectator ion appears in the same form and the same amount on both sides of the complete ionic equation, so it takes no part in the chemistry. When barium chloride meets sodium sulfate, sodium and chloride are spectators: they begin dissolved and end dissolved. Cancelling them leaves Ba2+ + SO42− → BaSO4 (s).
How do you write a net ionic equation step by step?+
Write the balanced molecular equation, assign every species a state using the solubility rules, split all aqueous strong electrolytes into ions to make the complete ionic equation, cancel anything identical on both sides, then reduce the surviving coefficients to their lowest ratio. This calculator performs all five steps and displays each one in the results table.
Which species must stay together and not be split into ions?+
Solids, pure liquids such as water, gases, and weak electrolytes are never split. Only soluble ionic compounds, strong acids and strong bases are written as separate ions. Acetic acid is aqueous but weak, so it is written HC2H3O2 (aq) rather than as H+ plus acetate, which changes the net ionic equation completely.
What solubility rules does this calculator use?+
Rule 1: all Group 1 and ammonium salts dissolve. Rule 2: all nitrates and acetates dissolve. Rule 3: chlorides, bromides and iodides dissolve except silver, lead(II) and mercury(I). Rule 4: sulfates dissolve except barium, lead(II), calcium, strontium and silver. Rule 5: hydroxides are insoluble except Group 1, ammonium and barium. Rule 6: carbonates, phosphates and sulfides are insoluble except Group 1 and ammonium.
What does it mean when there is no reaction?+
If both possible products are soluble, every ion appears unchanged on both sides and the whole equation cancels away. The calculator reports No reaction and lists all four ions as spectators. Mixing sodium chloride with potassium iodide is the standard example: you simply end up with a single solution containing Na+, Cl−, K+ and I−.
Why does a carbonate plus an acid produce carbon dioxide?+
Swapping partners would give carbonic acid, H2CO3, which is unstable at room temperature and decomposes immediately into water and carbon dioxide. So hydrochloric acid with sodium carbonate gives 2 H+ + CO32− → H2O (l) + CO2 (g). The escaping gas removes product from the system and drives the reaction to completion.
How do I balance a net ionic equation correctly?+
Balance the molecular equation first, carry those coefficients through the splitting step, then after cancelling spectators divide every remaining coefficient by their greatest common factor. Both atoms and total charge must balance. In Pb2+ + 2 I− → PbI2, the left side carries +2 and −2 for a net zero, matching the neutral solid on the right.
What is the difference between complete ionic and net ionic equations?+
The complete ionic equation shows every dissolved strong electrolyte broken into ions, spectators included, so it is a literal inventory of what is in the beaker. The net ionic equation is the same expression after the spectators have been cancelled, isolating the chemistry that actually occurs. Both appear in this calculator's results table so you can compare them directly.
Do net ionic equations need state symbols?+
Yes, they are essential. The symbols (aq), (s), (l) and (g) identify the driving force, since the whole point of the equation is usually to show a solid forming, a gas escaping or water being produced. Writing Ag+ + Cl− → AgCl without the (s) hides the very reason the reaction proceeds at all.
Can a reaction have no spectator ions at all?+
Yes. Mixing sulfuric acid with barium hydroxide gives both a barium sulfate precipitate and water, so nothing is left over to cancel and the complete ionic and net ionic equations are identical. This is why that mixture is a favourite conductivity demonstration: the bulb dims as the ions are consumed and the solution stops conducting.
Are net ionic equations used outside the classroom?+
Constantly. Water treatment chemists use them to plan phosphate and hardness removal, analytical chemists use them for gravimetric precipitation, and process engineers use them to predict scale formation in boilers and pipework. Writing only the reacting species makes it immediately obvious which ion concentration controls the outcome and therefore which dose to adjust.
Why does this calculator use a reagent list instead of free text?+
A curated list guarantees that both starting solutions are genuinely aqueous and that every ion charge is known exactly, so the balancing and the solubility decisions are deterministic rather than guessed from a typed string. The 35 reagents cover the salts, strong acids and strong bases that appear in almost every general chemistry exercise on double displacement reactions.
Tags: Net Ionic Equation Calculator Complete Ionic Equation Spectator Ions Solubility Rules Double Displacement Reaction Precipitation Reaction Calculator Formula Free Online

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What is a net ionic equation?

A net ionic equation shows only the species that actually change during a reaction, with every spectator ion removed. For silver nitrate and sodium chloride the molecular equation is AgNO3 + NaCl gives AgCl plus NaNO3, but the net ionic equation is simply Ag+ (aq) plus Cl- (aq) gives AgCl (s), because sodium and nitrate ions are unchanged on both sides.

What is a spectator ion?

A spectator ion appears in identical form and identical amount on both sides of the complete ionic equation, so it takes no part in the chemistry. In the reaction of barium chloride with sodium sulfate, sodium and chloride are spectators: they start dissolved and finish dissolved. Cancelling them leaves Ba2+ plus SO4 2- giving BaSO4 solid.

How do you write a net ionic equation step by step?

Write the balanced molecular equation, assign a state to every species using the solubility rules, split all aqueous strong electrolytes into their ions to make the complete ionic equation, cancel anything identical on both sides, then reduce the remaining coefficients to their lowest ratio. This calculator performs all five steps and shows each one.

Which species stay together in an ionic equation?

Solids, pure liquids such as water, gases, and weak electrolytes are never split. Only soluble ionic compounds, strong acids (HCl, HNO3 and H2SO4 here) and strong bases are written as separate ions. Acetic acid is a weak acid, so it is written as HC2H3O2 (aq) rather than as H+ plus acetate.

What are the solubility rules used here?

Rule 1: all Group 1 and ammonium salts dissolve. Rule 2: all nitrates and acetates dissolve. Rule 3: chlorides, bromides and iodides dissolve except those of silver, lead(II) and mercury(I). Rule 4: sulfates dissolve except barium, lead(II), calcium, strontium and silver. Rule 5: hydroxides are insoluble except Group 1, ammonium and barium. Rule 6: carbonates, phosphates and sulfides are insoluble except Group 1 and ammonium.

What happens when no reaction occurs?

If both possible products are soluble, every ion appears unchanged on both sides and the whole equation cancels. The calculator reports No reaction and lists all four ions as spectators. Mixing sodium chloride with potassium iodide is the classic case: you simply end up with a solution containing Na+, Cl-, K+ and I-.

Why does a carbonate plus acid give carbon dioxide?

Swapping partners would produce carbonic acid, H2CO3, which is unstable at ordinary temperature and immediately decomposes into water and carbon dioxide gas. So hydrochloric acid with sodium carbonate gives 2 H+ plus CO3 2- yielding H2O (l) plus CO2 (g), and the escaping gas is what drives the reaction to completion.

How do I balance a net ionic equation?

Balance the molecular equation first, then carry those coefficients through the splitting step. After cancelling spectators, divide every remaining coefficient by their greatest common factor. Both atoms and total charge must balance: in Pb2+ plus 2 I- giving PbI2, the left side carries +2 and -2 for a net zero, matching the neutral solid on the right.

What is the difference between complete ionic and net ionic equations?

The complete ionic equation shows every dissolved strong electrolyte broken into its ions, including the spectators. The net ionic equation is the same expression after the spectators have been cancelled. The complete form is useful for seeing exactly what is in the beaker, while the net form isolates the chemistry that actually happens.

Does the net ionic equation need state symbols?

Yes. State symbols (aq), (s), (l) and (g) are what identify the driving force, since the point of the equation is usually to show a solid forming, a gas escaping or water being produced. Writing Ag+ plus Cl- gives AgCl without the (s) hides the entire reason the reaction proceeds.

Can a net ionic equation have no spectator ions at all?

Yes. Mixing sulfuric acid with barium hydroxide produces both a precipitate and water, so nothing is left over to cancel and the complete ionic and net ionic equations are identical. This is unusual, and it is why that particular mixture is a favourite conductivity demonstration: the solution stops conducting as the ions are consumed.

Are net ionic equations used outside the classroom?

Constantly. Water treatment chemists use them to plan phosphate and hardness removal, analytical chemists use them for gravimetric precipitation, and process engineers use them to predict scale formation in boilers and pipework. Writing only the reacting species makes it obvious which ion concentration controls the outcome.

📌 Quick Tips

💡Only strong electrolytes are split into ions. Solids, liquids, gases and weak acids such as acetic acid are always written in molecular form.
💡If every ion cancels, there is genuinely no reaction. Mixing two soluble salts whose swapped partners are also soluble simply leaves a mixture of four ions.
💡The net ionic equation must balance in charge as well as in atoms. Check both sides before trusting a hand-worked answer.
💡Carbonic acid never survives: a carbonate plus a strong acid gives water and carbon dioxide gas rather than H2CO3 sitting in solution.
💡Coefficients in the net ionic equation are reduced to their lowest whole-number ratio, which is why 2 Na+ and 2 Cl- may cancel down to a simpler form than the molecular equation suggests.