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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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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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

science f3 chap 6 land and it s resources

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