IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: wanabeastarstudent on September 29, 2010, 11:55:38 am
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??? hey.. well i got a quiz on tuesday on thse things from the past year but i didnt study last year so can u help me wiv these topic n post websites plz?
*state of matter
*seperating techniques and mixtures
*atomic structure
*bonding (metallic,covalent,ironic and macromolecular)
thanks so much
and im doing extraction of iron (Fe), aluminuim and zinc do u have any websites? cuz i started skwl late so i missed out thanks :P u guys are great :) :-*please help
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https://studentforums.biz/references-and-resources/ultimate-resource-guide-for-igcse/
Check this out :
https://studentforums.biz/sciences/chemistry-p3-762010/
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this as well :)
https://studentforums.biz/sciences/chemistry-p6-185010/
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thanks <3 im confused can someone explain this please??
Extraction of metal (Aliminuim)
*low density ........ airoplane......body
*resist corrosion......>window+door frames
*reflection of heat......> food.........> container rust
*conductor or heat.....> kitchen wear
*conductor of electricity........> over head cables
please explain and can u give me any info about this topic im confused :-[ ugh.. n i need to know about zinc and copper aswel... hm.. thanks a bunch
is al high density or low? i dont even know wat it means :-[ :-[ :-X :-X
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Alright I shall start from scratch, to avoid confusion. ;)
Extraction of Aluminium.
Aluminium ore --> Bauxite (Aluminium oxide/Alumina Al2O3)
Separation method --> Electrolysis
(http://lgfl.skoool.co.uk/uploadedImages/Coord11.4_extraction%20of%20aluminium_v2.gif)
[If image too small - Right-click > View image]
Electrlysis is carried out in this, huge steel tank.
The walls are lined with Carbon which acts as the Cathode (-)
Huge blocks of carbon hang in the middle of the tank which act as the anode. (+)
Aluminium oxide/alumina is insoluble and it melts at 2045 *C, which is practically impossible to maintain that temperature in the tank environment. Therefore aluminium oxide is dissolved in molten Cryolite (sodium aluminium fluoride) which has a lower melting point.
Once this aluminium oxide dissolves, the aluminium ions and oxide ions are free to move. They move to the electrode of opposite charge.
At Cathode.
Aluminium ions gain electrons. (Reduction)
4Al3+ + 12e- ----> 4Al
At anode
Oxygen ions lose electrons. (Oxidation)
6O2- ----> 3O2 + 12 e-
This oxygen bubbles off as carbon dioxide as the anode itself is made of carbon. So these blocks are eaten away and eventually should be replaced.
Overall reaction
2Al2O3 ---> 4Al + 3O2
Properties of Aluminium.
Aluminium is a bluish-silver, shiny metal.
It has low density - it is very light in weight
Good conductor of heat and electricity
Malleable (can be bent easily) and ductile (can be drawn into wires very easily)
It is strong and highly uncreative (Aluminium has the tendency to form a thin coating of Al2O3 over its surface when exposed to air, it never gets 'rust') and is very light. This is very useful for manufacturing of aircraft (light and strong) and food containers (because it is highly uncreative and does not corrode)
Reflection of heat -> It is a shiny metal.
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Thank you GG for the links.
Zinc, copper and iron coming up shorty.
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Extraction of Zinc.
Zinc ore ---> zinc blende (zinc sulfide - ZnS)
First, it is roasted in air to give zinc oxide:
2ZnS + 3O2 ---> 2ZnO + 2SO2
Then the oxide is reduced in one of the following ways:
Method 1. Using carbon monoxide:
ZnO + CO --> Zn + CO2
The final mixture contains zinc and a slag of impurities. The zinc is separated from it by fractional distillation.
Method 2. Electrolysis
For this, zinc oxide is dissloved in sufuric acid to give zinc sulfate (salt) and water [Acid + Base -> Salt and Water]
Why this is done? For electrolysis, the general principle is the electrolyte (the solution in container) has to conduct electricity - so for metals or metal oxides it has to either be in molten form or their salt solution. Zinc oxide is a (basic) oxide and is insoluble in water and the melting point is very high. So the salt solution is obtained in order to carry put the electrolysis. So, not necessarily sulfuric acid must be used, any acid for that matter.
At cathode:
Zn2+ + 2e- ---> Zn (s)
This zinc is scraped off the cathode. This method is preferable as it gives zinc of very high purity.
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Extraction of Copper.
Copper ore ---> malachite (Copper (II) carbonate - CuCO3)
The reaction takes place in two stages :
Stage 1 - The malachite decomposes :
CuCO3 (s) ---> CuO (s) + CO2 (g)
Stage 2 - The copper (II) oxide is reduced by carbon :
2CuO (s) + C (s) ---> 2Cu (s) + CO2(g)
This copper is then purified by electrolysis.
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For extraction of iron, I shall post a picture from my textbook - explains it really well, after my scanner or even the webcam decide to function. :P ;)
OK not working out really well so here are the notes :
Extraction of iron.
Iron ore ---> haematite (Iron (II) Oxide - Fe2O3)
(http://www.chemguide.co.uk/inorganic/extraction/blastfurnace.gif) (http://scienceaid.co.uk/chemistry/applied/images/blastfurnace.jpg)
[If image too small - Right-click > View image]
yeah so as you can see the extraction of Fe takes place in a blast furnace.
Raw materials used to put at the top.
>Iron ore (Fe2O3)
>Coke (Main source for Carbon needed for the reduction process)
>Limestone (needed to remove the impurities in the form of 'slag')
Steps in which the extraction is conducted :
1. Iron ore, coke and limestone are fed into the top of the blast furnace.
2. Hot air blasted up the furnace from the bottom.
3. Oxygen from the sir reacts with coke to from carbon dioxide.
C (s) + O2 (g) ---> CO2 (g)
4.Carbon dioxide reacts with more coke to form carbon monoxide
CO2 (g) + C (s) ---> 2CO (g)
5.Carbon monoxide is a reducing agent.
Iron (II) oxide is reduced to iron :
Fe2O3 (s) + 3CO (g) ---> 2Fe (l) + 3CO2 (g)
6. Dense molten iron runs to the bottom of the furnace and is run off. There are many impurities in iron ore. The limestone helps to remove these shown in steps 7 and 8.
7. Limestone is broken down by heat to calcium oxide :
CaCO3 (s) ---> CaO (s) + CO2 (g)
8. Calcium oxide reacts with impurities like sand (silicon dioxide) to form a liquid called 'slag':
CaO (s) + SiO2 (g) ---> CaSiO3 (l)
(calcium silicate)
the liquid slag falls to the bottom of the furnace and is tapped off.
The overall reaction :
2Fe2O3 (s) + 3C ---> 4Fe + 3CO2
Reduction reaction stages :
Stage 1 - The coke reacts with oxygen blasted into the furnace :
C (s) + O2 (g) ---> CO2 (g)
Stage 2 - The carbon dioxide is reduced by unreacted coke to form carbon monoxide :
CO2 (g) + C (s) ---> 2CO (g)
Stage 3 - The iron (iii) oxide is reduced by the carbon monoxide to iron :
Fe2O3 (s) + 3CO (g) ---> 2Fe (s) + 3CO2 (g)
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??? hey.. well i got a quiz on tuesday on thse things from the past year but i didnt study last year so can u help me wiv these topic n post websites plz?
*state of matter
*seperating techniques and mixtures
*atomic structure
*bonding (metallic,covalent,ironic and macromolecular)
thanks so much
and im doing extraction of iron (Fe), aluminuim and zinc do u have any websites? cuz i started skwl late so i missed out thanks :P u guys are great :) :-*please help
OK, here are a couple of ppts. The rest I'll try to type out notes after a while.
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Some notes which might help.
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SEPERATION OF SUBSTANCESS isnt working?? why
but the rest is amazing :) plz see if u can do anything about seperation of substances and is there any questions on the past papers that i can do relating to the things i will get a quiz on plz past paper 3 and 6 thanks
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SEPERATION OF SUBSTANCESS isnt working?? why
but the rest is amazing :) plz see if u can do anything about seperation of substances and is there any questions on the past papers that i can do relating to the things i will get a quiz on plz past paper 3 and 6 thanks
look at the pps i gave u for chem ppr 6 and check the first question from year 2005 and up they're solved , it'll help u out a lilttle bit ;)
as for anything else i suggest u revise chromatography June 2010 chem ppr 6 there is a good Q on chromatography ;) ...Well i'll try to help u tmrrw (tho i'll be comin late bas iA i'll try to help ya out ) :D
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:O so chromotography is involved??
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For extraction
ppr 3
m/j/02 - 1a-1d
m/j/03 - 1
m/j/05 - 6a
o/n/05 - 5b
m/j/06 - 1
m/j/07 - 6
bonding-
ppr 3
m/j/04 - 1b-1c
o/n/04 - 5b
m/j/05 - 5b iii
o/n/05 - 1a
m/j/06 - 4
m/j/07 - 2
m/j/07 - 4a - 4c
o/n/08 - 2
o/n/09 - 5
chromatography/separating techniques-
ppr 3
m/j/05 - 5ai - 5aiii
o/n/07 - 1,3a,bi-bii
ppr 6
m/j/02 - 2
o/n/03 - 1
o/n/04 - 7
m/j/05 - 6
o/n/05 - 3
o/n/06 - 5
m/j/09 - 1,3
o/n/09 - 7
m/j/07 - 1,3
o/n/08 - 1
m/j/09 - 1
states of matter-
ppr 3
o/n/05 - 2a
atomic structure-
ppr 3
m/j/08- 2
hey wanna i will give u the 90's ppr tom - have a test tom - so cant give dose now :(
Take care n keep smiling :D
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SEPERATION OF SUBSTANCESS isnt working?? why
but the rest is amazing :) plz see if u can do anything about seperation of substances and is there any questions on the past papers that i can do relating to the things i will get a quiz on plz past paper 3 and 6 thanks
Hm.. try now. [This post]
Thanks loads Esha. Highly appreciated. ;)
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Hm.. try now.
Thanks loads Esha. Highly appreciated. ;)
np vin :D :D
wht shld i say fr u then ??? ::) - higher than highly highly highly appreciated :P
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np vin :D :D
wht shld i say fr u then ??? ::) - higher than highly highly highly appreciated :P
hahahaha! Believe me, your job required waayy more efforts and is waayy more tedious. :P ;)
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hahahaha! Believe me, your job required waayy more efforts and is waayy more tedious. :P ;)
tedious-----ofc nt----just had to turn the pages :D :D
anyway Take care n keep smiling :D
have a chem test tom :'( :'(
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tedious-----ofc nt----just had to turn the pages :D :D
anyway Take care n keep smiling :D
have a chem test tom :'( :'(
hahaha but still, they're too many. ;)
yeah you too. :)
Oh, best of luck. You'll do really well. ;)
Extraction of Iron (https://studentforums.biz/sciences/chemistry-seperating-techinques-quiz-on-tuesday-help/msg354133/#msg354133)
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hahaha but still, they're too many. ;)
yeah you too. :)
Oh, best of luck. You'll do really well. ;)
Extraction of Iron (https://studentforums.biz/sciences/chemistry-seperating-techinques-quiz-on-tuesday-help/msg354133/#msg354133)
thank u :D :D
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Esha u deserve a + 1000000000000000000000000000000000000000000000000000000 infinity rep <3
Honey it is AMAZING <3
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:O so chromotography is involved??
habeebti don't ya remember when mr.sumaiah used to give u Qs in her exams and if u look in her notes it's within the first two chapters i guess ;)
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*state of matter
*seperating techniques and mixtures
The three states of matter :
>Solid
>Liquid
>Gas
Properties of solid
Rigid – fixed definite shape
Highly incompressible
Least intermolecular space
Intermolecular force of attraction is greatest
Type of motion of molecules : They vibrate along their mean position
Properties of liquid
Indefinite shape – takes the shape of the container
Incompressible
Intermolecular space greater than solids and lesser than liquids
Intermolecular force of attraction lesser than solids
Type of motion of molecules : Random, constant movement of molecules
Properties of gas
Indefinite shape – Completely fills the container creating a specific amount of pressure of the walls (dependent on the concentration of gas/number of molecules)
Highly compressible
Greatest intermolecular space
Intermolecular force of attraction least.
Type of motion of molecules : Random and uncertain (Brownian motion)
(also refer ppt)
Separation techniques and methods:
>Mixture of two solids : one soluble in water, other insoluble - Dissolve the mixture in water> Filter the contents> Dry the residue on paper> Evaporate the solution to obtain soluble solid.
>Mixture of solid particles (eg. sand) and water : Sedimentation (allow the solid to settle) > Decantation (carefully pour the solution from the container in order to leave the (sand) particles in the bottom of the original container. > Filtration (Filter any solid particles present after decantation in the solution of water)
>Mixture of solid particles (eg. sand/salts etc) and iron > Use magnet.
>Mixture of two or more miscible liquids > Fractional distillation
>Mixture of two miscible liquids > Separating funnel.
>Idea of chromatography
[refer ppt for more info and diagrams]
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*atomic structure
*bonding (metallic,covalent,ironic and macromolecular)
Atomic structure.
An atom consists of a nucleus and particles revolving around it at high speeds called electrons. These electrons are placed in different energy levels. If these electrons stop revolving, or slow down their motion, the nucleus will attract them towards itself (due to the difference of charges) and 'consume' them.
The nucleus consists of neutrons and protons. The nucleus determines the mass of the atom and the proton number determines the Atomic number of the atom.
The distribution of electrons for normal elements is as follows, i.e the maximum number of electrons each shell can accommodate:
1st- shell: K -> 2
2nd- shell: L-> 8
3rd- shell: M-> 18
4th shell: N -> 32
and so on.. The general formula is 2n2. Where 'n' is the shell number.
Remember:
(In reference to the Periodic table)
All the elements in the same group (column) have same number of outer shell electrons (also known as valence shell electrons)
The period number shows how many shells there are for each element.
Proton - Positively charged particles. Found in the nucleus. Atomic mass of 1.
Neutrons - No charge. Also present in the nucleus. Atomic mass of 1
Electrons - Negatively charged particles. Orbit around the nucleus in specific paths. Mass negligible (1/1837)
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OK man, the bonding stuff tomorrow. I have very little time, sorry. Hope it won't be too late. ;)
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heyy thanks it helped.. d u have the bonding i highly apreciated it :P
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heyy thanks it helped.. d u have the bonding i highly apreciated it :P
Isma3i ana mit2akda inu if u ask Mrs.Sumaiah 3ala hal 2as2ila then she'll answer Wallah ...O ba3deen i gave u that tutor's No. try him OUT he HELPED me loads in Chem i fricikn LUBed the subject cuz of the way he teaches , it's like mujarad mal ma3looma tid5ul rasi it does NOT seem to get OUT ;)
Gd Lcuk in that Quiz ;)
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Esha u deserve a + 1000000000000000000000000000000000000000000000000000000 infinity rep <3
Honey it is AMAZING <3
hehe.....thnxx :D :D
chromatography/separating techniques-
ppr 6
s/93 - 3c-3f
w/93 - 2
s/94 - 1,2
w/ 94 - 2
s/95 - 2,3a,7c
w/95- 2
s/96 - 2
w/96 -3d-3g
s/97 - 1,5
w/97 - 1,3
s/98 - 6,7
w/98 - 1,2,3
w/99 - 2,4
s/00 - 6
w/00 - 1,5
o/n/01 - 1a
ppr 3-
w/95 - 5a
s/00 - 5 d
bonding-
ppr3
s/93 - 3c,4
s/94 - 3ai,3bi,3bii
w/94 - 1c
s/95 - 2 d
w/95 - 2 ci
s/96 - 1a
s/97 - 1 cii
s/98 - 5 d
w/98 - 2c
w/99 - 3a
s/00- 1
n/00 - 3 b
o/n/01 - 5a b c
Extraction-
ppr 3
w/93 - 5a
w/94 - 1a
s/96 - 3
w/96 - 1a
w/97 - 4a,b,c
w/99 - 1 a
o/n/01 - 4a b
states of matter-
ppr 3
s/95 - 2a,2b
s/96 - 5a
srry didn't give it on thursday :( :( ws too lazy n rly had a lot of work >:( :(
temme if u want the pprs frm 88 :)
anyway gud luck.....Take care.....Keep Smiling :D :D