4CH1
States of Matter
Principles of Chemistry
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 6% of your exam marks.
stable
Low
Stable6%
Appears regularly as short-answer questions on particle diagrams and state changes.
| Term | Meaning | Example |
|---|---|---|
| Solvent | The substance (usually a liquid) that does the dissolving | Water in seawater |
| Solute | Whatever gets dispersed into the solvent | Sodium chloride in seawater |
| Solution | The single-phase mixture once the solute is fully dispersed | Seawater |
| Saturated solution | Holds as much solute as it can take at the current temperature; further additions stay undissolved | Salt solution sitting over crystals |
| Soluble | Able to dissolve in a stated solvent | Sugar in water |
| Insoluble | Unable to dissolve in a stated solvent | Sand in water |
- Solubility is solvent-specific
- Iodine: insoluble in water, soluble in hexane
- Always quote the solvent when describing a substance as "soluble" or "insoluble"
Exam tip
Define a saturated solution
Write (two marks): (1) a solution holding the maximum amount of solute that can dissolve in it; (2) at that temperature. Any extra solute added stays undissolved.
Watch out: the "at that temperature" point is a whole mark on its own and is the one most often dropped — solubility changes with temperature, so a solution saturated when cool may not be when warm.