Topic 1b: Experimental techniques
Activity C1b.1 Orientation Learning objectives
To review knowledge of measuring instruments and equipment. To review knowledge of the methods for separating mixtures.
Learning outcomes
Know the appropriate apparatus for the measurement of time, temperature, mass and volume, including the use of burettes, pipettes and measuring cylinders. Know that mixtures can be separated in a number of different ways depending on the physical properties of the substances.
Resources Student Book pages 21–27 Files on CD-ROM: C1b.1a_tech_notes Resources for demonstration (see Technician’s notes, below)
Approach Start with a quick quiz in which students have to name some common laboratory measuring equipment. This could include a stopwatch, thermometer, electronic scales or balance, burettes, pipettes and measuring cylinders. Set up demonstrations of distillation, fractional distillation, filtration, crystallisation and chromatography. As students observe each process, ask them to identify which states of matter are being separated in each process. You will need to judge whether students have enough prior knowledge to omit Activity C1b.3. SAFETY INFORMATION Wear eye protection. Ethanol is highly flammable.
Technician’s notes Be sure to check the latest safety notes on these resources before proceeding. The following resources are needed for a demonstration of methods of purification: stopwatch, thermometer, electronic balance, burette, pipette and measuring cylinder distillation apparatus (Student Book page 26), with dilute blue washable ink, for example fractional distillation apparatus (Student Book page 27), with ethanol and water, for example filtration, with sand and water, for example crystallisation apparatus (Student Book page 25), with salt solution, for example chromatography apparatus (Student Book page 23), with black soluble ink, for example
Cambridge IGCSE Chemistry Teacher Pack
32
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