unit 1 – day 9 qualitative analysis. qualitative analysis techniques qualitative analysis uses...

Unit 1 – Day 9

Qualitative Analysis

Qualitative Analysis Techniques

• Qualitative analysis uses physical and chemical properties to identify substances.

• We have already learned two such techniques:– Ionic and covalent properties– Spectroscopy

• The rest of the unit focuses on two more techniques:– Flame tests– Solubility

Recall

• Two substances are mixed up. One is labelled substance A, the other substance B.

• The two substances are known to be calcium bromide and dichlorobenzene (a substance made up of carbon, hydrogen and chlorine).

• Substance A has a strong odour, and will not dissolve in water.

• Identify substance A and B• Dichlorobenzene is substance A.

Recall

• Describe how you could use a spectrometer, and the following image to identify the gas in a lighting display.

Flame Tests

• Flame tests are similar to spectroscopy.• This time we are using heat to excite the

electrons instead of electricity.• The colour of the flame helps to identify the

substance.

Flame Tests

• With flame tests, it is the metal ion that determines the colour that the compound will produce.

• For example, Strontium produces a deep red flame.

• Strontium chloride flame test

Flame Test Lab

• In the following lab, you will need to do some flame tests.

• Fill in the table of known colours, and then use these to identify the unknown solutions.