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7/28/2019 Science F3 Chap 6 Land and It s Resources
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F3 Science Chapter 6
Land and Its Resources
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Minerals
Minerals natural elements or compounds
present in Earth's crust
characteristics:
hard
insoluble in water
not decomposed by heat
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Minerals
eg ofnatural elements: gold, silver,
platinum, antimony, arsenic, iron,copper, mercury
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Minerals
eg ofnatural compounds(metallic elements
combined with non-metallic elements):bauxite,
heamatite, calcite,malachite
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Minerals
Most minerals, are found as natural compounds
in the form of:
oxides
sulphides
carbonates
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Elements present in minerals that arefound as natural compounds
Natural compound Mineral Elements
Oxide Haematite Iron, oxygenCassiterite Tin, oxygen
Carbonate Calcite Calcium, carbon, oxygen
Malachite Copper, carbon, oxygen
Sulphide Iron pyrite Iron, sulphur
Galena Lead, sulphur
Silicate China clay Aluminium, silicon, oxygen
Calcium silicate Calcium, silicon, oxygen
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properties of some minerals
1. Metal oxide hard
do not dissolve in water(except potassiumoxide,sodium oxide, magnesium oxides andcalcium oxide forms alkaline solution)
do not decompose on heating
decompose upon heating with carbon if lessreactive with carbon
Equation:
metal oxide + carbon ----->metal + carbon
dioxide
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properties of some minerals
2. Metal Suphide hard
do not dissolve in water(except potassiumsulphide and sodium sulphide)
decompose on heating -Breaks down into a metaloxide and releases sulphur dioxide gas
Equation:metal sulphide + oxygen ----->metal oxide +sulphur dioxide
This gas changes the potassium manganate (VII)
solution from purple to colourless
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properties of some minerals
3. Metal Carbonate hard
do not dissolve in water(except potassiumcarbonate and sodium carbonate)
decompose on strong heating-Change to theiroxides and carbon dioxide when burnt in air.
Equation?metal carbonate------>metal oxide + carbondioxide
The carbon dioxide gas causes lime water to turn
cloudly
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6.2 Reactions Between Metal andNon-metal
elements are classified in metals and non-metals: reacts to form compounds
eg: zinc oxide, calcium carbonate....
active metal reacts more vigorouslycompared tothe less reactive metals with non-metals
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6.2 Reactions Between Metal and Non-metal Reaction of metals with oxygen
A metal oxide is formed
Equation?
Metal + oxygen (heated)--> Metal oxide
metal reaction product
magnesium burns with blinding
flame
magnesium oxide
(white)
aluminium burns very brightly aluminium
oxide(white)
zinc glows brightly andburns
zinc oxide(yellow whenhot and white when cold)
iron glow brightly andproduces sparks
iron oxide(red)
copper glows brightly copper oxide(black)
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6.2 Reactions Between Metal and Non-metal
Reaction of metals with sulphur A metal sulphide is formed
Equation?
Metal + Sulphur (heated)--> Metal sulphide
metal reaction product
magnesium burns vigorously magnesium sulphide
(white)
aluminium burns brightly aluminium sulphide (grey)
zinc glows brightly and
spreads quickly
zinc sulphide ( white )
iron glows and spreads
quickly
iron sulphide(black)
copper glows and spreads
slowly
coppersulphide(black)
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6.3 Silicon Compounds
silicon - second most abundant element in the
Earths crust.
does not exist as a free element---compounds
Silicon compounds in the Earths crust silica,
silicates
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Silica silicon dioxide
Silica silicon dioxide
compound of silicon and oxygen
eg: pure sand,quartz,flint
silicates
compound of silicon, metal and oxygen
colour of silicates depends on metal init, eg: precoius stones (ruby, topaz,jade)
other silicates: clay, asbestos
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Silica and Silicates
Insoluble in water
Do not react with acid
Do not break down when heated
Thats why they are very stable in the Earth
crust
Hence, not easily eroded, found in largequantities in the Earths crust
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uses of silica and silicates
1. silica - glass, cement, concrete, bricks
2.clay - cups,plates, bowls
3.mica- insulators in electric iron
4.asbestos- heat insulators for fireman's clothes
5.silica gel- drying agent
6.sodium silicate - preserve eggs and furniture'svarnish
7.coloured silicates- decorative precious stones
8.silicon - electronic chips
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6.4 Calcium compounds
calcium - reactive metal - easily forms
compound
eg: calcium oxide, calcium chloride, calcium
carbonate, calcium hydroxide
Calcium carbonate -lime- produce limestone
and marbles Consists of calcium, carbon, and oxygen
natural calcium: shells of animals, bones and
teeth, corals, egg shells
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Calcium Carbonate
Insoluble in water
Reacts with dilute hydrochloric acid to produce
salt, water and carbon dioxide
Equation
calcium carbonate + dilute hydrochloric acid ---->
calcium chloride + water + carbon dioxide calcium carbonate + dilute nitric acid ---->
calcium nitrate + water + carbon dioxide
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Calcium carbonate When heated strongly, calcium carbonate
changes to calcium oxide (quicklime) and
carbon dioxide is released calcium carbonate---> calcium oxide + carbon
dioxide
Few drops of water are added to calcium oxide,
effervescence occur and heat is given off,forming calcium hydroxide
When more water is added, it dissolves to formcalcium hydroxide solution --limewater
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uses of calcium compounds
1.marble - table tops, statue,covering walls andfloor
2.limestone - build roads,cement and glass,smelting of tin ore and iron ore
3.quicklime - lower the acidity of soil, prepare
acetylene gas, drying agent, prepare slaked lime4.slaked lime - making white wash, mortar,
caustic soda, water treatment plant
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Petroleum
petroleum- thick, sticky, black oil found
trapped in ground formed millions years ago when organism living
in sea died and settled at the bottom of sea
natural gas- found above the surface of
petroleum
Mixture of several hydrocarbons, which consist
ofhydrogen and carbon only
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fractional distillation of petroleum
Hydrocarbons in petroleum are separated by a
process called fractional distillation
fractional distillation - a process in whichpetroleum is boiled and differenthydrocarbons(fraction) are distilled off at diff
temperature hydrocarbons with lower boiling point separated
first
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natural gas
mixture of gases- propane, butane and ethane
used as:
fuel in home, factories and gas power station
raw material in making petrochemicals such as
urea, ammonia do not pollute the air - hardly produce soot
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coal natural fuel resource formed from plants in swampy area
plants died and buried become sediment - -highpressure and heat turns them into hard black solid --coal
not a good fuel - produces lots of fume and pollutes theenvironment
used for: fuel for warming house
boiling water to get steam which spins turbines and dynamosin power station
making dyes, coke, explosives, paints, fertilisers and medicine