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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 354773 times)

Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1020 on: May 17, 2010, 12:12:38 pm »
Quote from: Kimo Jesus on May 17, 2010, 10:35:09 am
+ dilute nitric acid

test for sulfate ions

and do we get white ppt?
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InshaAllah 8 A* in IGCSE....Ameen.....

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Offline Kim

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1021 on: May 17, 2010, 12:13:08 pm »
yup
u get a white ppt
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After all is said and done, more is said than done.

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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1022 on: May 17, 2010, 12:13:34 pm »
Quote from: Baladya on May 17, 2010, 12:03:50 pm
Shazizzle ur lucky, my school didn't even finish one paper with us NOT ONE!!!

Anyway, enough  with the stupid school :P
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_qp_6.pdf
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2006%20Nov/0620_w06_ms_6.pdf

Q)3)c)ii) Can someone 'translate' what the mark scheme says :P

they simply mean that it might contain some impurity ..
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1023 on: May 17, 2010, 12:14:49 pm »
O ya :P Thanks. Lets just hope they start speaking normal english...

Hey sorry :P Same paper ;D Hmm.. 4)b)iii) it says Hydrogen... where did it come from ??  Is it cuz its AQUEOUS Copper Sulphate?
« Last Edit: May 17, 2010, 12:19:55 pm by Baladya »
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1024 on: May 17, 2010, 12:27:07 pm »


Yeah, we  start IGCSE in grade 8, so we get a whole extra year, grade 10, to solve papers and clear doubts. Cool innit? :P
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1025 on: May 17, 2010, 12:31:00 pm »
Quote from: Baladya on May 17, 2010, 12:14:49 pm
O ya :P Thanks. Lets just hope they start speaking normal english...

Hey sorry :P Same paper ;D Hmm.. 4)b)iii) it says Hydrogen... where did it come from ??  Is it cuz its AQUEOUS Copper Sulphate?

Umm, the observations say 'lighted splint pops', so that's just the test for hydrogen, proving its presence.

You don't need to know why, but , yes, I believe because of the aqueous. :P It's water, so contains H+ and OH- ions.
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1026 on: May 17, 2010, 12:32:46 pm »
Quote from: Shazizzzle on May 17, 2010, 12:27:07 pm

Yeah, we  start IGCSE in grade 8, so we get a whole extra year, grade 10, to solve papers and clear doubts. Cool innit? :P

OMG 0.0 Its cool ya but no offense kinda stupid ;) Its just wrong to spend all that time studying the same stuff... One of the things i hate about IGCSE, is that they make u do it their way. (u have to know how to answer, solve questions, same style) Like u might know the right answer, but they still give it wrong cuz u didnt write it right way.. WTF 0.o thats just gay. The only good thing about it is that we dont memorize, we understand (to a certain extent xD)
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1027 on: May 17, 2010, 12:33:16 pm »
Quote from: Shazizzzle on May 17, 2010, 12:31:00 pm
Umm, the observations say 'lighted splint pops', so that's just the test for hydrogen, proving its presence.

You don't need to know why, but , yes, I believe because of the aqueous. :P It's water, so contains H+ and OH- ions.
thx ;)
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1028 on: May 17, 2010, 12:35:57 pm »
Okay guys, correct me if I'm wrong, and if you can find and accurate source of these, please share.

-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I

-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate

-All carbonates are insoluble except Sodium, potassuim and ammonium carbonates, which are soluble.

-All hydroxides are insoluble except Sodium, potassium and ammonium hydroxides, which are soluble.

-All nitrates are soluble

Thanks :)
« Last Edit: May 17, 2010, 12:50:30 pm by Shazizzzle »
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1029 on: May 17, 2010, 12:41:24 pm »
Correct. Tho i don't know Hydroxides and some of the first line i also dont know :P
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Offline Ghost Of Highbury

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1030 on: May 17, 2010, 12:43:51 pm »
This is wat my book says. Cross check it. :)

Insoluble compounds.

Chlorides, bromides, iodides of silver and lead.

Sulfates of Calcium, barium and lead.

All hydroxides except those of group 1

All carbonates except those of group 1

Metal oxides except group 1 and 2s.
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1031 on: May 17, 2010, 12:46:53 pm »
yup ;) ;)

add sodium with potassium .. i guess thts understood

All sulphides and sulphites are insoluble except potassium , sodium , ammonium

All OXIDES are insoluble except calcium, potassium and ammonium ,

Ca(OH)2 is partially soluble right .. jus wanna make sure ..  ;) ;)

NOTE :
 PbCl2 is soluble in hot water
 AgCl is soluble in aq. ammonia
« Last Edit: May 17, 2010, 12:49:27 pm by ~VIN1094~ »
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1032 on: May 17, 2010, 12:49:26 pm »
Acids - Donate Proton (H+)
Bases - Accept Proton (H+)

Alkalis - soluble bases

Basicity - No of replaceable hydrogen ions
Monobasic - 1 replaceable H+ e.g HCl
DiBasic - 2 replaceable H+ e.g H2SO4

Strong acids/alkalis - fully dissociate/ionise - HCl & NaOH
Weak acids/alkalis - only partially dissociate/ionise - CH3COOH & NH4OH

Indicators
Red Litmus paper - Red in acidic - blue in alkaline
Blue Litmus paper - Red in acidic - blue in alkaline
methyl orange - orange/pink in acidic - yellow in alkaline
methyl red - red in acidic - yellow in alkaline
Phenolphthalein - colourless in acidic - pink in alkaline

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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1033 on: May 17, 2010, 12:51:44 pm »
sh*t MAN. I need that xD :D Thankss :P
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1034 on: May 17, 2010, 12:57:30 pm »
Quote from: ~VIN1094~ on May 17, 2010, 12:46:53 pm
yup ;) ;)

add sodium with potassium .. i guess thts understood

All sulphides and sulphites are insoluble except potassium , sodium , ammonium

All OXIDES are insoluble except calcium, potassium and ammonium ,

Ca(OH)2 is partially soluble right .. jus wanna make sure ..  ;) ;)

NOTE :
 PbCl2 is soluble in hot water
 AgCl is soluble in aq. ammonia

Yup. The study guide says, ALL HYDROXIDES ARE INSOLUBLE EXCEPT GROUP 1 METALS (SODIUM, POTASSIUM ETC), CALCIUM, STRONTIUM AND BARIUM.
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