Solubility & Recrystallization Calculator
From the solubility per 100 g of water, compute the maximum dissolved amount, the composition of a saturated solution, and the crystals precipitated on cooling or evaporation — with the mass-balance steps shown.
Try an example
Choose a pattern and enter the solubility and masses.
Done
Solubility & Recrystallization Calculator
How to use
- 1
Pick a pattern
Choose composition, precipitation on cooling, or evaporation plus cooling.
- 2
Enter the solubility and masses
Enter the solubility in g per 100 g of water and the water or saturated-solution mass from the problem.
- 3
Check the steps and assumptions
Follow the high-temperature composition, the amount still soluble when cold, and the difference, along with assumptions such as anhydrous crystals.
Features
- Three patterns: composition, precipitation on cooling, and evaporation with cooling
- Start from either the water mass or the saturated-solution mass
- Shows the working: hot composition, cold solubility, then the difference
- Everything runs in your browser; no sign-up and nothing is uploaded
Use cases
Check homework
Verify recrystallization problems such as potassium nitrate with the working shown.
Plan an experiment
Estimate the theoretical crystal yield before cooling a saturated solution.
Read solubility curves
Compute precipitation from two temperatures and check how to read the graph.
Details
Solubility is the maximum mass of a substance that dissolves in 100 g of water at a given temperature. A solution holding that maximum is saturated, and its ratio is "100 g water + S g solute = (100 + S) g solution". For other amounts of water or solution, scale this ratio proportionally.
Crystals precipitate on cooling because solubility falls while the amount of water stays the same. The amount dissolved while hot minus the amount that can stay dissolved when cold is the mass of crystals formed. Starting from a saturated solution of mass M, the shortcut M × (S₁ − S₂) ÷ (100 + S₁) gives the same result.
This tool assumes anhydrous crystals and no evaporation of water. When a hydrate such as CuSO₄·5H₂O precipitates, the crystals carry water away, so the remaining water changes and this formula does not apply. In practice, supersaturation, impurities and cooling rate can make real yields differ from the theoretical value. Note that gas solubility decreases as temperature rises — the opposite of most solids.
FAQ
Should I start from the water mass or the saturated-solution mass?
Both give the same answer. From W g of water use (S₁ − S₂) × W ÷ 100; from M g of saturated solution use M × (S₁ − S₂) ÷ (100 + S₁). Use whichever the problem provides to keep the calculation short.
Does this work when a hydrate such as CuSO₄·5H₂O precipitates?
No. This tool assumes anhydrous crystals. A hydrate carries water out of the solution, so the remaining water changes and the yield differs. Solve such problems with separate mass balances for the anhydrous solute and for water.
What if evaporation and cooling happen together?
Use the evaporation-and-cooling mode. Enter the mass of water evaporated and the tool applies the cold solubility to the remaining water. To model evaporation only, set both solubilities to the same value.
How many digits should I keep?
Do not round intermediate values; round once at the end to match the problem or the required significant figures. The display keeps up to six significant digits as a guide. Real experiments usually recover less than the theoretical yield.
Related guide
GuideHow to Calculate pH: Formulas, Acid-Base Types & Worked Examples
Master pH calculations from pH = −log₁₀[H⁺] for strong and weak acids, polyprotic acids, and bases via pOH. Features step-by-step examples, temperature effects on neutral pH, a common liquids reference table, and a logarithmic scale diagram.
GuideHow to Calculate Crystals Precipitated on Cooling
Find the mass of crystals that precipitate when a saturated solution is cooled: dissolved while hot, still soluble when cold, and the difference.
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Verified: Textbook cases (135 to 45 with 100 g of solution giving 38.2979 g, 160 to 30 giving 50 g, and 100 g evaporated from 200 g of water giving 96 g) plus error handling are covered by browser tests