MYP 9

The Chemist's tools 9.1.4 - Measuring and recording

Objectives

Students should:

  • Differentiate apparatus according to its purpose, measuring, holding, supporting etc.
  • Be aware of associated inaccuracies in measuring instruments and apparatus.

E-assessment

Matter: states and properties of matter.

Particle/kinetic theory, diffusion.

Pure and impure substances. Types of mixtures (solutions, oils, alloys, emulsions)

Separation techniques, including filtration, distillation [including crude oil - myp10], chromatography.

Activity

They are essential for observation, But become worthless if we cannot communicate our observations in an unambiguous fashion. Communication requires the correct use of scientific vocabulary and is supported by standardised (relative) measurements.

Experiment 2

Measure 50cm3 water into a beaker.

Record the mass by pouring into a beaker on a balance set to zero.

Repeat using a measuring cylinder and a burette.

Correlate results over the whole class.

Notes

Errors and repetition.

How accurate are we?

Percentage and absolute errors.

Tolerance of balance = ± 0.01 g (explanation - two measurements each with an error of ± 0.005g are taken)

Discussion of measurements, errors (systematic and measurement), instrumental tolerance and reliability, precision and inaccuracy.

Burettes, pipettes

Student follow up

Experiment write up identifying the most accurate measuring glassware.

Teacher's notes

The experiment depends on the use of an electronic balance as the instrument with the least error.

Data tables of water density at different temperatures can add sophistication for more able students.

Resources

Density of water at different temperatures


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