Solubility
Introduced| English |
|---|
| saturated solution/ˈsætʃəreɪtɪd səˈluːʃn/ |
Why oil and water won't mix
- Salt vanishes in water but sand does not.
- Oil floats in a stubborn layer, refusing to blend.
- Whether something dissolves follows a simple rule of thumb.
- "Like dissolves like" -- match the type and it mixes.
Like dissolves like
- Polar solvents dissolve polar and ionic solutes.
- Nonpolar solvents dissolve nonpolar solutes.
- Water (polar) dissolves salt; oil (nonpolar) does not.
A polar solvent like water best dissolves solutes that are...
By "like dissolves like", polar water dissolves polar and ionic solutes.
Oil (nonpolar) dissolves readily in water (polar).
Unlike polarities do not mix, so oil and water separate.
The guiding rule for dissolving is "like dissolves ____".
Similar polarities dissolve each other.
How much will dissolve
- A saturated solution 饱和溶液 holds the maximum solute at that temperature.
- Below that limit it is unsaturated, and more can still dissolve.
- Add extra beyond the limit and it simply settles out.
A solution holding the maximum solute at a given temperature is...
At the maximum it is saturated; more solute just settles out.
Temperature changes solubility
- Most solids dissolve more in hot solvent than in cold.
- Gases do the opposite -- they dissolve less as it warms.
- That is why a warm soda goes flat faster.
As temperature rises, the solubility of most gases in water...
Gases become less soluble in warmer water -- warm soda goes flat.
Most solids dissolve more in hot solvent than in cold.
Higher temperature usually raises a solid's solubility.
Will oil dissolve in water?
- Oil is nonpolar; water is polar.
- "Unlike" will not mix, so the oil stays as a separate layer.
Soluble or insoluble?
Use the solubility rules to sort each ionic compound.
"Like dissolves like" is about polarity -- polar and ionic dissolve in polar water, nonpolar in nonpolar solvents. Solids usually get more soluble as temperature rises, but gases get less soluble. And a saturated solution is not full forever: heat it and it can dissolve more.
Whether a solute dissolves follows "like dissolves like": polar and ionic in polar solvents, nonpolar in nonpolar. A saturated solution holds the most solute possible at that temperature. Warming usually raises a solid's solubility but lowers a gas's.