Dissolving: how much can water hold?
Stir salt, sugar and sand into water. Find out which ones dissolve, and how much salt water can hold.
Core concept
In short: Stir solids into water: some disappear, some do not, and water can only take so much.
Some solids dissolve, and water can dissolve only a limited amount
Topic: Solutions and solubility
When a solid dissolve: To mix into a liquid so completely that you can no longer see the pieces. All key words, it breaks into particle: A tiny piece that matter is made of, far too small to see. All key words too small to see and spreads through the liquid. The result is a solution: A mixture where one substance has dissolved completely in a liquid, like salt water. All key words. The solid is the solute: The substance that dissolves, like the salt in salt water. All key words, and the liquid (here, water) is the solvent: The liquid that something dissolves in, like the water in salt water. All key words. Some solids do not dissolve at all. Even a solid that dissolves has a limit: after a certain amount, the water cannot hold any more.
What you will learn
- Tell the difference between soluble and insoluble solids.
- Describe what happens to a solute when it dissolves.
- Explain what a saturated solution is.
Before you start
- Know that grams (g) measure mass and millilitres (mL) measure volume.
Materials
- Water (50 mL in each beaker)
- Table salt
- Sugar
- Sand
Equipment
- 3 beakers (100 mL)
- Spoon that holds 5 g
- Stirring rod
Procedure
- Each beaker already holds 50 mL of water.
- Add 5 g of salt to Beaker A, 5 g of sugar to Beaker B and 5 g of sand to Beaker C.
- Stir each beaker and observe.
- Keep adding salt to Beaker A, 5 g at a time, stirring after each spoonful, until no more will dissolve.
How this simulation is simplified
- The water is at room temperature (about 20 °C). Warm water would dissolve more.
- 50 mL of water dissolves about 18 g of salt here. Real values depend on temperature and the type of salt.
- Dissolving happens straight away when you stir. In real life it can take a minute or two.
- The volume of the added solids is ignored.