ATMOSPHERE OCEAN ROCKS & MINERALS F4 CHEMISTRY ATMOSPHERE OCEAN ROCKS & MINERALS

PLANET EARTH (matter) GASES IN THE AIR COMPOUNDS IN SEA WATER COMPOUNDS OF METALS

MATTER (substance) Gas Solid Liquid (solution) ATMOSPHERE EARTH OCEAN \

THE ATMOSPHERE Atmosphere AIR Earth

AIR (composition) NITROGEN (78%) OXYGEN (21%) NOBLE GASES (1%) CARBON DIOXIDE (0.03-0.04%) WATER VAPOUR OTHERS

AIR (separating gases) Liquefaction of air AIR (g) → AIR (l) Fractional distillation of liquid air (Fractionating column) Nitrogen (g) (bp=-196oC) AIR (l) Oxygen (g) (bp=-183oC)

TEST FOR GASES OXYGEN NITROGEN CARBON DIOXIDE RELIGHTS A GLOWING SPLINT NITROGEN NO SIMPLE TEST CARBON DIOXIDE TURNS LIME WATER TO MILKY Lime water (calcium hydroxide solution) Milky substance (calcium carbonate)

WORD EQUATION CARBON DIOXIDE turns LIME WATER to milky Carbon + Calcium → Calcium + water dioxide hydroxide carbonate (g) (aq) (s) (l)

TEST FOR GASES (cont.) CARBON DIOXIDE (excess) CHLORINE MILKY SOLUTION TURNS COLOURLESS Colourless solution (calcium hydrogencarbonate solution) CHLORINE Bleaches wet litmus paper

OCEAN OCEAN - SEA WATER SEA WATER - AQUEOUS SOLUTION SEA WATER CONTAINS WATER (96.5%) DISSOLVED SALTS (2.5%) Mostly common salt (sodium chloride) OTHERS(includes dissolved gases) (1%)

Obtain common salt from Sea water FILTRATION RESIDUE – mud, sand, solid particles FILTRATE – sea water EVAPORATION of the filtrate Dilute solution → Concentrated solution → Saturated solution CRYSTALLIZATION Cool slowly – to obtain large crystals of Salt (NaCl) Filtration – to obtain Salt

Obtain pure water from Sea water DISTILLATION Boiling Water (l) → Water (g) (water vapour) Condensing Water (g) → Water (l) Distillate - pure water / distilled water

TEST FOR COMMON SALT SALT IS AN IONIC COMPOUND CATION (from metals) Test – FLAME TEST ANION (from non-metals) Test – Chemical Test

FLAME TEST FOR CATIONS Nichrome wire Concentrated hydrochloric acid Bunsen burner Colour of flame Potassium compound Sodium compound Calcium compound

TEST FOR ANION (chloride) Silver nitrate solution & dilute nitric acid Add to a solution of chloride White precipitate appear White precipitate is SILVER CHLORIDE Word equation:

TEST FOR ANION (sulphate) Barium chloride solution & dilute hydrochloric acid Add to a solution of sulphate White precipitate appear White precipitate is BARIUM SULPHATE Word equation:

TEST FOR ANION (carbonate) Dilute hydrochloric acid Add to a solution of carbonate Effervescence Colourless gas is CARBON DIOXIDE Word equation:

TEST FOR WATER Dry cobalt(II) chloride paper (blue) Water turns blue cobalt(II) chloride paper pink.

ELEMENTS OF WATER COMPOUND → ELEMENTS Word equation WATER → OXYGEN + HYDROGEN (Compound) (Elements of water) ELECTRICITY is required SOURCE OF ELECTRICITY (CELL) POSITIVE ELECTRODE (+) NEGATIVE ELECTRODE (-) The process is ELECTROLYSIS OF WATER

Dissolved salts in Sea water Sodium chloride (NaCl) Magnesium chloride (MgCl2) Potassium sulphate (K2SO4) Calcium chloride (CaCl2) Dissolved ions (Dissolved ions of Na+, Cl-, Mg2+, SO42-, K+, Ca2+)

Electrolysis of Sea water Sea water is a mixture Water + dissolved Salts Substances from electrolysis of sea water using carbon electrodes: Hydrogen (at the negative electrode) Chlorine (at the positive electrode) Sodium hydroxide (in the solution)

EARTH’S CRUST (Minerals) ROCK is a mixture of MINERALS MINERALS Compounds Elements Gold Silver Compounds of metals Compounds of non-metals Al2O3 CaCO3 SiO2

ORES ORE Examples of Ore Rock containing compounds of metals Bauxite (aluminium ore) Haematite (iron ore) Cinnabar (mercury ore)

EXTRACTION OF METALS FROM ORES Physical separation Heating of ore Heating the ore with carbon Electrolysis of molten ore

CHALK, LIMESTONE, MARBLE Calcium carbonate exists in 3 forms: Chalk Limestone Marble Formation of chalk Skeleton or shells of dead sea animals High pressure or temperature Long time

Investigating Calcium carbonate Action of heat Calcium Calcium + carbon carbonate oxide dioxide Action of dilute hydrochloric acid Effervescence Calcium chloride, carbon dioxide, water Action of water Insoluble in water

LIMESTONE and related compounds Calcium carbonate ( formula) QUICKLIME Calcium oxide ( formula) SLAKED LIME Calcium hydroxide ( formula) LIMEWATER Saturated solution of calcium hydroxide (formula )

Further reactions Calcium oxide reacts with water to form calcium hydroxide Calcium hydroxide is slightly soluble in water Limewater is a saturated solution of calcium hydroxide Limewater can be used to test for carbon dioxide gas (The milky substance is calcium carbonate)

EROSION Erosion is a complicated process Causes of erosion Broken down into smaller pieces Changed into other material Lost of surface material Causes of erosion Heat Rain (acid rain) Wind, running water, gravity

FORMATION OF LIMESTONE CAVES Heat decomposes limestone forms calcium oxide and carbon dioxide Acid rain reacts with limestone forms salt and carbon dioxide (carbon dioxide dissolves in rain water to form carbonic acid) Limestone is slightly soluble in water