Chemistry / Unit 10: Solutions, Acids and Bases
10.1 Solutions and Solubility
Notes
A solution is a homogeneous mixture. The solute is what dissolves; the solvent does the dissolving (often water).
- "Like dissolves like": polar solvents dissolve polar and ionic solutes (salt in water); nonpolar solvents dissolve nonpolar solutes (oil in hexane).
- Solubility is the most solute that dissolves in a given amount of solvent at a given temperature.
- Unsaturated: can dissolve more. Saturated: holds the maximum. Supersaturated: holds more than the maximum; unstable.
- Most solids dissolve better in hotter water. Gases dissolve better in colder water and at higher pressure (why soda goes flat when warm or opened).
- Stirring, crushing and heating make a solid dissolve faster.
Practice
Which substance is most likely to dissolve in water?
Water is polar, so it dissolves ionic and polar substances like NaCl.
A solution holds the most solute it can at a given temperature. It is:
Saturated means it is at its maximum; any extra solute will not dissolve.
Why does an open soda lose its fizz faster when it is warm?
Gas solubility decreases as temperature rises, so $\text{CO}_2$ escapes.
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