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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 354719 times)

Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1050 on: May 17, 2010, 02:10:33 pm »
Quote from: hamz on May 17, 2010, 02:04:32 pm
its used as an indicator...to check presence of starch!!..not iodine...
...... :P

check it urself .. chem not bio ..

http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_ms_6.pdf

http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2007%20Jun/0620_s07_qp_6.pdf

Q 4 a. its a diff ques.
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Offline High-R

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1051 on: May 17, 2010, 02:11:36 pm »
Quote from: hamz on May 17, 2010, 02:04:32 pm
its used as an indicator...to check presence of starch!!..not iodine...
...... :P
i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????
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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1052 on: May 17, 2010, 02:18:10 pm »
Quote from: mdwael on May 17, 2010, 01:05:50 pm
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/1993-2003/chemistry1993-2000answers.pdf

In this one at may/june 2000 answer 6 b what does O.I.M mean?
"fill the burette with O.I.M hydrochloric acid solution"
u will only be marked if uy include hcl in ur ans....i think so:p
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1053 on: May 17, 2010, 02:20:00 pm »
Quote from: hamz on May 17, 2010, 02:11:36 pm
i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????
lol hamz u startd past pprs
:P
By the way <konsa ppr kr rahi ho? jaLdi bata>
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1054 on: May 17, 2010, 02:20:24 pm »
So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1055 on: May 17, 2010, 02:22:53 pm »
Quote from: hamz on May 17, 2010, 02:11:36 pm
i mean i jus wanted to know tht do u mean tht we r checkin IOdine 's presence by starch????

wht not ?? not specifically but u hav a look at the paper .. it has to mean that way .. if u can check the presence of starch by iodine .. why cant u do that the other way .. ultimately u get  blue/black colouration ..
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Offline guMnam

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1056 on: May 17, 2010, 02:23:16 pm »
Quote from: Shazizzzle on May 17, 2010, 02:20:24 pm
So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S
aaa wat is a hydrated salt:S
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1057 on: May 17, 2010, 02:24:02 pm »
Sab chup beth ke past papers karo. :P
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1058 on: May 17, 2010, 02:24:56 pm »
Quote from: gumnam on May 17, 2010, 02:23:16 pm
aaa wat is a hydrated salt:S

One with water.
i.e opposite to anhydrous.
Blue Copper (II) Sulphate crystals are hydrated. The white anhydrous salt has no water.
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1059 on: May 17, 2010, 02:25:21 pm »
Quote from: Shazizzzle on May 17, 2010, 02:24:02 pm
Sab chup beth ke past papers karo. :P

jaise tum kahoo =P
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Offline DEGO

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1060 on: May 17, 2010, 02:25:42 pm »
guys dont panic BUT THE EXAM IS TOMORROW  :o :o :o time flies
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1061 on: May 17, 2010, 02:26:13 pm »
Quote from: Shazizzzle on May 17, 2010, 02:20:24 pm
So, when something 'smells of vinegar', it's an organic salt? :S
Also, when condensation forms on the top of the tube, it's a hydrated salt? :S
And because it 'smells like petrol', it's an alkane/organic hydrocarbon? :S

very trueeeeeeeeeeeeeeeeeeeee

alcohol  not alkane but yea the 5th alkane on words are liquids so ye a maybe i think soo ! can u check again on teh mark scheme?
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1062 on: May 17, 2010, 02:27:38 pm »
i.e it loses its 'water of crystallisation'.
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1063 on: May 17, 2010, 02:28:51 pm »
Quote from: gumnam on May 17, 2010, 02:23:16 pm
aaa wat is a hydrated salt:S

SOME salts can be hydrated. This means they fit water molecules in them. The formula is like this: CuSO4.5H20......... MgSO4.7H20..... CoCl2.6H20

If you heat these they will lose their water molecule and become anhydrated.
This is why they are used in testing of water. If solution has water, they will turn blue. If u add the solution and it doesnt have water, then they will stay white
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1064 on: May 17, 2010, 02:31:46 pm »
Quote from: 6394 on May 17, 2010, 02:20:00 pm
lol hamz u startd past pprs
:P
By the way <konsa ppr kr rahi ho? jaLdi bata>

bhaaag kyun gaye!!!!! k call me wen u cum onlin agn
me goin 2 hav some sleep< SHAYED lol>
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