aristo chemistry

Contents

PART XV ANALYTICAL CHEMISTRY
Chapter 63 Detecting the presence of chemical species
Action of heating solid sample strongly

1
Chapter 64 Separation and purification methods
Centrifugation
Sublimation
Partition equilibrium of a solute between two immiscible solvents
Two-dimensional thin-layer chromatography

2
2
3
6
Chapter 65 Quantitative methods of analysis
Detection of end point in acid-alkali titration

8
Chapter 66 Instrumental analytical methods
More about infrared spectroscopy
More about mass spectrometry

12
15
Chapter 67 Contribution of analytical chemistry to our society
Gas chromatography-mass spectrometry

32
PART XV ANALYTICAL CHEMISTRY

Chapter 63 Detecting the presence of chemical species

Action of heating solid sample strongly
Heating the solid sample strongly is one of the preliminary tests of substances. This can be done by heating the sample over a non-luminous Bunsen flame in the laboratory. In case there is any gas evolved, further tests can be done to identify the gas. See Table S63.1.
Observation
Inference
Yellow sublimate
Sulphur
Violet vapour and dark grey shiny sublimate
Iodine
Dark red sublimate
Iron(III) chloride, FeCl3
White sublimate
Ammonium halides e.g. AlCl3
Water vapour evolved
Hydrated salts; hydrogencarbonates; some hydroxides
Colour change
Some hydrated salts
Rust red residue
Fe2O3 formed (from decomposition of iron compounds)
Black residue from blue or green sample
CuO formed (from decomposition of copper(II) compounds)
Yellow residue when hot, white when cold
ZnO formed (from decomposition of zinc compounds)
Orange residue when hot, yellow when cold
PbO formed (from decomposition of lead(II) compounds)
Ammonia evolved
Some ammonium salts
Carbon dioxide evolved
Some carbonates; hydrogencarbonates
Nitrogen dioxide evolved
Nitrates and nitrites (except those of potassium, sodium and ammonium)
Oxygen evolved
Nitrates (except NH4NO3); some