CHAPTER 18 – SOLUTIONS AND SOLUBILITY Crystallisation
Crystals are tiny, solid particles that often form regular shapes. Salt, snowflakes and diamonds are all examples of crystals. Crystals form when a saturated solution is cooled. The process is called crystallisation.
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Dame Kathleen Lonsdale (1903–1971) was born in Newbridge, County Kildare. Working as part of a crystallography research team in London, she investigated how diamonds are created and was one of the first scientists to use X-rays to study crystals.
:Fig. 18.10 Crystals
:Fig. 18.11 Kathleen Lonsdale
Summary questions 1. Copy and complete the sentences.
The substance that dissolves is called the ____________. The substance the solute dissolves into is called the ____________. A ____________ is formed when a solute dissolves in a solvent.
2. Use a diagram to explain what happens when a sugar cube dissolves in water. 3. Describe how you would investigate whether a substance is soluble or insoluble. 4. What activities could be carried out to help a solute dissolve in a solvent? 5. Describe what is meant by solubility. 6. What unit is used to measure solubility? 7. Match the example with its description.
Example
1. Concentrated orange juice in water 2. A fizzy drink
3. A marshmallow 4. Sugar in tea
8. Use diagrams to explain the following: a. Dilute solution b. Concentrated solution c. Saturated solution
Description
a. A gas dissolved in a solid b. A solid dissolved in a liquid c. A liquid dissolved in a liquid d. A gas dissolved in a liquid