Stir sugar into water and it seems to vanish. It has not — it has dissolved, and the result is a solution.
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Get these three names right and half the chapter is done.
🥄 Naming the parts
| Word | Meaning | In sugar water |
|---|---|---|
| Solute | the substance that dissolves | sugar |
| Solvent | the one that does the dissolving | water |
| Solution | the two together | sugar water |
Water is called the universal solvent because it dissolves more substances than any other liquid. That is also why it is so easily polluted — almost anything will dissolve into it.
Dissolved is not destroyed. The sugar is still there — you can taste it, and it reappears if the water evaporates. The total mass does not change either.
A solvent cannot take an unlimited amount. When no more will dissolve, the solution is saturated.
🧂 The three kinds of solution
| Kind | Meaning |
|---|---|
| Unsaturated | more solute can still dissolve |
| Saturated | no more will dissolve at that temperature |
| Supersaturated | holding more than it normally could, usually after heating and cooling gently |
Temperature matters, and in opposite ways. Heating makes solids dissolve more readily in water — but it makes gases dissolve less. That is why a warm fizzy drink goes flat quickly, and why warm river water holds less oxygen for fish.
Three things make a solid dissolve faster, and every one of them is a standard exam answer.
⚡ What makes dissolving faster
| Do this | Why it works |
|---|---|
| Stir it | fresh solvent keeps meeting the solute |
| Heat it | particles move faster and mix sooner |
| Powder it | more surface is exposed to the solvent |
Why powdered sugar dissolves fastest. A lump touches the water only on its outside. Grinding it exposes far more surface, so far more of it can be attacked by the water at once.
12 questions on solutions and solubility. 🍀
