CSEC Chemistry • Lesson 2 of 2States of Matter · Myers Science Hub Student Centre
CourseCSEC Chemistry
Practice formatMCQ • Structured • Experimental
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Learning objectives
- Distinguish among solid, liquid and gas by particle model and observable properties.
- Explain changes of state in terms of energy and particle arrangement.
- Interpret simple heating/cooling observations.
- Plan a fair test involving evaporation.
Core notes
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Particle arrangement | Very close, ordered | Close, irregular | Far apart |
| Movement | Vibrate about fixed positions | Move/slide past one another | Rapid random motion |
| Shape | Fixed | Takes container shape | Fills container |
| Compressibility | Very low | Very low | High |
Melting & boiling
Energy is absorbed. Particle kinetic energy increases until attractive forces are sufficiently overcome for a new state to form.
Freezing & condensation
Energy is released to the surroundings. Particles move less rapidly and attractive forces become more effective.
Evaporation
Occurs at the surface and can occur below the boiling point. Faster particles escape from the liquid.
Sublimation
A solid changes directly to gas without becoming liquid first; the reverse process is deposition.
Video lesson
Paper 01-style MCQ
1. Which property is explained mainly by the large spaces between gas particles?KC • 1
2. During melting at the melting point, energy supplied is used mainly toUK • 1
Paper 02-style structured questions
3. State TWO differences between particles in a liquid and particles in a gas.KC • 4
Any two paired comparisons, 2 marks each: liquid particles are close together whereas gas particles are far apart; liquid particles move past one another but gas particles move more rapidly/randomly; attractive forces are stronger in liquids than gases.
4. Explain why a sealed syringe containing air can be compressed more easily than one completely filled with water.UK • 3
Gas particles have large spaces between them (1), so pressure can push them closer together (1). Liquid particles are already close together with little empty space, so water is difficult to compress (1).
Experiment-type question
5. A student claims that increasing exposed surface area increases the rate of evaporation. Design an experiment to test the claim.XS/PD • 8
Hypothesis (1); change exposed surface area using containers of different diameter (1); measure mass/volume lost in fixed time or time for fixed amount to evaporate (1); control initial liquid volume, temperature, air movement and liquid type (2); replicate and average (1); present results as evaporation rate versus surface area (1); conclude only from trend (1).