Water, Solubility and Solutions
Section: Chemistry | Syllabus: Cambridge Primary Stage 5 Science (0097)
Solubility as a Property
- A solute is the substance that dissolves.
- A solvent is the liquid in which the solute dissolves.
- A solution is the clear, evenly mixed liquid that is formed.
- Whether a solid dissolves is a property of both the solid and the liquid - it is not only about the solid.
- A liquid that dissolves one substance well may not dissolve another substance at all.
When a solute dissolves, its particles separate and spread among the solvent particles
Important Properties of Water
- Water behaves differently from many other substances because its solid state (ice) takes up more space than its liquid state.
| Property | Stage 5 fact |
|---|---|
| Melting point | Pure water melts at 0 °C |
| Boiling point | Pure water boils at 100 °C under normal conditions |
| Freezing | Water expands when it solidifies, which is unusual for a substance |
| Solvent action | Water dissolves a wide range of substances |
Making a Solution
- During dissolving, solute particles separate from each other and spread among solvent particles.
- The solute is still present even if it can no longer be seen.
- Stirring can make dissolving happen faster by spreading the solute particles out sooner, but it does not guarantee that every substance will dissolve.
Question: A learner stirs 6 g of salt into water until it cannot be seen. Name the solute and solvent, and explain what happened to the salt. [3]
The solid being dissolved is the solute: salt. The liquid doing the dissolving is the solvent: water. The salt particles spread through the water; they did not vanish. AnswerSolute: salt. Solvent: water. The salt particles separated and spread through the water to form a solution.
Common Mistakes
MistakeThe solute disappears, so it is no longer present.
FixThe solute remains in the solution as particles spread among the solvent particles.
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