Solubility Rules Checker Form
Choose a cation and anion, then apply the rules checker. The result appears above this form after submission.
Formula Used
This checker uses a rule-based chemistry model rather than a single numeric formula. It first balances ionic charges, then applies standard aqueous solubility priorities and exceptions.
| Part | Expression | Meaning |
|---|---|---|
| Charge Balance | MxAy |
x = |anion charge| / gcd and y = |cation charge| / gcd. |
| Rule Engine | Class = f(cation family, anion family, exceptions) |
The result depends on the rule hierarchy and exception checks. |
| Precipitation Hint | Low, Moderate, High |
Used as a practical guide for whether solid formation is likely. |
How to Use This Calculator
- Select the cation from the first list.
- Select the matching anion from the second list.
- Set the water condition and optional temperature field.
- Add any study or lab notes for context.
- Click Check Solubility to run the rule engine.
- Read the result block above the form.
- Review the governing rule, confidence, and precipitation tendency.
- Use the CSV or PDF buttons to save the result.
Example Data Table
These examples show how common salts behave under the standard rules set.
| Compound | Cation | Anion | Predicted Class | Reason |
|---|---|---|---|---|
| NaNO3 | Sodium | Nitrate | Soluble | Nitrates are broadly soluble. |
| AgCl | Silver | Chloride | Insoluble | Silver halide exception applies. |
| CaSO4 | Calcium | Sulfate | Slightly Soluble | Calcium sulfate is a borderline sulfate. |
| Ba(OH)2 | Barium | Hydroxide | Soluble | Barium hydroxide is a hydroxide exception. |
| FePO4 | Iron(III) | Phosphate | Insoluble | Most phosphates are insoluble. |
| MgF2 | Magnesium | Fluoride | Slightly Soluble | Magnesium fluoride follows a fluoride exception. |
Core Solubility Rules Reference
- Group 1 and ammonium salts are treated as soluble.
- Nitrates, acetates, chlorates, perchlorates, and bicarbonates are treated as soluble.
- Chlorides, bromides, and iodides are soluble except with silver, lead(II), and mercury(I).
- Most sulfates are soluble except with barium, strontium, and lead(II). Calcium and silver sulfates are limited.
- Most hydroxides are insoluble. Barium and strontium hydroxides are soluble, while calcium hydroxide is only slightly soluble.
- Most carbonates, phosphates, chromates, oxalates, sulfites, and silicates are insoluble unless paired with Group 1 or ammonium.
- Most sulfides are insoluble, though calcium, strontium, and barium sulfides show higher solubility.
- Some real systems depend on concentration and Ksp, so this checker is best for standard instructional use.
Frequently Asked Questions
1. What does this checker predict?
It predicts whether an ionic compound is soluble, slightly soluble, or insoluble in water by applying common classroom solubility rules and exceptions.
2. Does the tool calculate Ksp values?
No. It uses rule logic instead of numerical Ksp data. For precise equilibrium calculations, consult a Ksp table or a dedicated solubility product calculator.
3. Why can some salts be only slightly soluble?
Slightly soluble salts dissolve partially. They sit between clearly soluble and clearly insoluble behavior, often because the compound has a known exception.
4. Why is ammonium usually soluble?
Ammonium salts are widely treated as soluble in introductory chemistry because they remain well dispersed in water across most standard examples.
5. Can temperature change real solubility?
Yes. Real solubility often shifts with temperature. This checker keeps the standard rule result, so unusual thermal behavior should be verified separately.
6. Why do halides have important exceptions?
Halides are usually soluble, but silver, lead(II), and mercury(I) form very stable solids with chloride, bromide, and iodide, causing precipitation.
7. Is this suitable for reaction prediction?
Yes, for many aqueous double-displacement problems. It helps identify when a product may remain dissolved or appear as a precipitate.
8. When should I use a more advanced method?
Use a more advanced method when concentration, pH, complex ions, or exact equilibrium behavior matters. In those cases, rule checks alone may be incomplete.