HIGHER CHEMISTRY - Oxidation - Education Scotland

HIGHER
CHEMISTRY
Safety Measures
- Oxidation -
Preparation/provision of: Main Hazards Control Measures
1 mol l -1 sulphuric acid from
concentrated acid
0.1 mol l -1 potassium
dichromate from solid
Concentrated acid causes severe
burns to eyes and skin.
Toxic by ingestion.
Carcinogenic and very toxic by
inhalation.
Skin sensitiser.
Very toxic to the aquatic
environment.
Benedict's solution Harmful by ingestion owing to
copper salts.
Tollens' reagent Both 2 mol l -1 sodium hydroxide and
solid silver nitrate are corrosive.
propanal Highly flammable (fl. pt. 15 °C).
Toxic by skin absorption and by
ingestion.
Vapour is harmful and irritates eyes,
skin and lungs.
propanone Highly flammable (fl. pt. -20 °C).
Low toxicity but harmful by
ingestion.
Vapour irritates eyes, skin and
lungs.
Notes
UNIT 2
PPA 1
Wear goggles or faceshield and pvc
gloves. Add concentrated acid
slowly with stirring to chilled water
of volume equal to about half the
final volume.
Wear eye protection and nitrile
gloves.
Because of coarse granular nature of
crystals it is easy to prepare solution
without forming a dust aerosol.
Wear eye protection. If prepared
see recipe in Hazardous Chemicals
Manual.
Wear eye protection and gloves.
Must be prepared immediately
before use.
Wear eye protection and nitrile
gloves.
Dispense in fume cupboard or in
well-ventilated room. Supply in
small reagent bottles (50 or 100
cm 3 ).
Wear eye protection and nitrile
gloves.
Dispense in fume cupboard or in
well-ventilated room.
This experiment should be carried out in a well-ventilated room.
Propanal has been recommended as the aldehyde rather than ethanal since the latter is
more volatile and is a carcinogen.
Glucose solution could be used in place of propanal - it gives a better 'silver mirror' test.
It is important that the Tollens' reagent be prepared just prior to its being used since it
becomes explosive on evaporation. For the same reason residues must be washed down
the drain with copious amounts of water.
Fehling's solutions No. 1 (harmful) and No. 2 (corrosive) can be used as an alternative to
Benedict's solution.
Sandell's reagent can also be used as a substitute for Benedict's solution. Its preparation is
described in the Hazardous Chemicals Manual under Fehling's solutions No. 1 and No. 2.