Solubility
Definition and meaning of Solubility in chemistry.
Solubility is the maximum amount of a chemical substance that can dissolve in a liquid. It measures exactly how much solid, liquid, or gas can mix into a specific solvent. When a liquid cannot hold any more of the substance, we call it a saturated solution.
In more detail
Temperature changes have a huge impact on how much material can dissolve in a liquid. For most solid chemicals, hot liquids can dissolve much more material than cold liquids. The extra heat provides energy to break apart the strong bonds holding the solid together.
Gases behave in the exact opposite way when they are mixed into a liquid. Warm liquids hold less gas because the heated gas molecules gain energy and escape into the air. Pressure also matters for gases, as high pressure forces more gas molecules into the liquid.
Chemists use a simple rule called "like dissolves like" to predict how things will mix. Substances with similar electrical charges will easily mix and dissolve into each other. Water has polar molecules, so it easily dissolves other polar substances like salt and sugar.
Oil has nonpolar molecules, so it will never dissolve in a polar liquid like water. You can measure this property using units like grams per hundred milliliters or moles per liter. Knowing these exact numbers helps chemists design specific mixtures and prevent accidental solid clumping.
Key facts
| Field | Physical Chemistry |
|---|---|
| Key principle | Like dissolves like |
| Temperature effect on solids | Usually increases in hot liquids |
| Temperature effect on gases | Usually decreases in hot liquids |
| Common units | Grams per 100 mL, moles per liter |
| Related state | Forms a saturated solution at the limit |
Table salt, known as sodium chloride, has a very specific solubility limit in pure water. At room temperature, you can dissolve exactly 36.0 grams of salt into 100 milliliters of water. If you heat the water to 60 degrees Celsius, the capacity only increases a small amount. You can then dissolve about 37.3 grams of salt into that same volume of hot water. If you add any more salt than this absolute limit, it will just sink to the bottom.
Frequently asked questions
How is solubility different from dissolution?
Solubility is a specific physical limit of how much material can dissolve. Dissolution is the actual action or process of the material dissolving into the liquid.
Why does sugar dissolve better in hot water?
Hot water has more thermal energy. This extra energy makes the water molecules move faster, which helps break apart the sugar crystal structure much more quickly.
Why does soda go flat when it gets warm?
Gases have a lower solubility in warm liquids. When the soda warms up, the dissolved carbon dioxide gas gains energy and escapes into the surrounding air.