DSE Chem revision
Topic 1. Planet Earth
A. The atmosphere
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Composition of air:
Nitrogen N2
Oxygen O2
Argon Ar
Carbon dioxide CO2
Water vapour H2O -
separation of oxygen and nitrogen from liquid air by fractional distillation
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Test for oxygen - relight glowing splint
B. The ocean
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composition of sea water
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Extraction of common salt from sea water
Filtration
Evaporation
Crystallisation
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Isolation of pure water from sea water
Distillation -
Tests to show the presence of sodium and chloride in a sample of common salt
sodium ion - flame test
chloride ion - silver nitrate test -
Test for the presence of water in a sample
Anhydrous copper(II) sulphate - white to blue
Dry cobalt(II) chloride paper - blue to pink
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Electrolysis of sea water and uses of the products
Hydrogen
Chlorine
Sodium hydroxide
C. Rocks and minerals
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rocks as a source of minerals
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isolation of useful materials from minerals as exemplified by the extraction of metals from their ores
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limestone, chalk and marble as different forms of calcium carbonate
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erosion processes as exemplified by the action of heat, water and acids on calcium carbonate
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thermal decomposition of calcium carbonate
CaCO3 --> CaO + CO2 -
Test for carbon dioxide
Limewater - turn milky
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Tests to show the presence of calcium and carbonate in a sample of limestone/chalk/marble
calcium ion - flame test
carbonate ion - dilute HCl
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