MYP 6 Science - Chemistry

MYP 6.1.5: Testing substances

Objectives:

  • To introduce the concept of testing as applied to chemical substances and materials.
  • Understand that physical properties refer to measurable (quantitative) or observable (qualitative) characteristics.
  • To understand that a new substance is formed in a chemical change.
  • To introduce the investigation write up format.
  • To construct a filtering system using a funnel and paper.

Physical properties

A physical property is a characteristic of a substance that can be observed or measured. It does not depend on the amount of the substance.

  • Colour
  • Appearance (powder, crystalline etc)
  • State
  • Density
  • Melting and/or boiling point
  • Electrical conductivity

Measure the density of three colourless liquids. Explain that this can be done by recording the mass of a measured volume of liquid.

Measure 10cm3 of liquid into a beaker that has been pre-weighed. Density is calculated by dividing the mass (grams) by the volume in cm3.

  • Water
  • Glycerol
  • Ethanol

Compare the results between the groups. Why are they not exactly the same?

Chemical properties

The concept of a test should be introduced as a means of obtaining information about the nature of a process. Chemists investigate the chemical properties of substances by subjecting them to heat, exposing them to a naked flame or by mixing them with other substances and observing any changes.

Process tests to involve three stages (before - during - after):

  1. observation and recording before
  2. observation and recording during the application of some aspect (change)
  3. observation and recording after.

Demo or circus:

One or more reactions and discuss observations with the students.

Do these involve physical or chemical changes?

  1. Magnesium burning in air
  2. Sodium hydroxide solution added to iron(II) sulphate solution and left to stand
  3. Making invisible ink with cobalt(II) chloride solution

Resources

Science Spotlight 7: p74-77


 
previous page
next page
Copyright: 2013 Isis Publication