The solubility rules reference lists all standard solubility rules for ionic compounds in water, plus a precipitation predictor that shows whether mixing two solutions produces a precipitate and displays the net ionic equation.
Solubility Rules
Standard rules for ionic compounds in water at room temperature
| # | Ion / Group | Solubility | Exceptions |
|---|
Precipitation Predictor
Enter two ionic compounds to predict whether mixing their solutions forms a precipitate (double displacement reaction).
How to Use the Solubility Rules Reference
Solubility rules help predict the outcome of double displacement (metathesis) reactions between ionic compounds in aqueous solution. When two ionic solutions are mixed, the cations and anions trade partners, and you use solubility rules to determine if any product is insoluble (precipitates).
Step 1: Use the Rules Table
The solubility rules table lists common ions and whether their compounds are generally soluble or insoluble. Use the search box to filter by ion name or chemical formula. For example, searching "chloride" shows all the chloride solubility rules at once.
Step 2: Predict Precipitation
Select two ionic compounds from the dropdowns and click "Predict Precipitation." The tool performs the double displacement: Compound A (C₁A₁) + Compound B (C₂A₂) → C₁A₂ + C₂A₁, then checks each product against solubility rules.
Example: AgNO₃ + NaCl
When silver nitrate (AgNO₃) and sodium chloride (NaCl) solutions are mixed, the double displacement gives AgCl and NaNO₃. Checking rules: NaNO₃ is soluble (all Na⁺ compounds are soluble, all NO₃⁻ are soluble). AgCl is insoluble (Ag⁺ chlorides are exceptions to the "soluble chlorides" rule). Therefore AgCl precipitates. The net ionic equation is Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
Key Memory Aids
Memorize the soluble "always" rules: Group 1 metals (Li, Na, K, Rb, Cs) always soluble. All nitrates (NO₃⁻) always soluble. All acetates (CH₃COO⁻) soluble. Then memorize insoluble categories: hydroxides (OH⁻) except Group 1 and Ba²⁺. Carbonates (CO₃²⁻) except Group 1 and NH₄⁺. Sulfides (S²⁻) except Group 1 and Group 2 and NH₄⁺. Phosphates (PO₄³⁻) except Group 1 and NH₄⁺.
FAQ
What are solubility rules?
Solubility rules are guidelines that predict whether an ionic compound will dissolve in water (soluble) or form a solid precipitate (insoluble). They are empirical rules based on observed solubility data and are essential for predicting the products of double displacement reactions.
Are all nitrates soluble?
Yes, essentially all nitrate (NO₃⁻) salts are soluble in water with no common exceptions. This makes nitrate salts very useful as soluble sources of metal cations in solution chemistry.
Which chloride compounds are insoluble?
Most chlorides are soluble, but there are key exceptions: AgCl (silver chloride), PbCl₂ (lead(II) chloride), and Hg₂Cl₂ (mercury(I) chloride) are insoluble. This is the basis of the silver chloride precipitation test for chloride ions.
How do you predict if a precipitate forms?
When two ionic solutions are mixed, consider the double displacement: the cations and anions swap partners. Apply solubility rules to each possible product. If either product is insoluble, a precipitate forms. Write the net ionic equation showing only the ions that combine to form the precipitate.
Is this solubility reference free?
Yes, completely free with no signup required. All lookups and predictions run in your browser.
What is a net ionic equation?
A net ionic equation shows only the ions that actually participate in forming the precipitate. Spectator ions (ions that remain dissolved) are canceled from both sides. For AgNO₃ + NaCl → AgCl↓ + NaNO₃, the net ionic equation is Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
Are all sulfates soluble?
Most sulfates are soluble, with notable exceptions: BaSO₄ (barium sulfate), PbSO₄ (lead(II) sulfate), and SrSO₄ (strontium sulfate) are insoluble. CaSO₄ (calcium sulfate, gypsum) is slightly soluble. Ag₂SO₄ is slightly soluble. The BaSO₄ precipitation test identifies sulfate ions in solution.