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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 357029 times)

Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2670 on: June 06, 2010, 08:16:31 am »
Quote from: Raywin on June 06, 2010, 08:13:47 am
Oh, so repeating units are just monomers? Ryte :) Thanks a lot once again.. ;D

for polyethene only 1 type of monemer

for nylon , 2 types of monomers , diamine and dicarboxylic acid (so i prefer to call this the repeating unit of nylon )
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Offline Raywin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2671 on: June 06, 2010, 08:25:30 am »
Quote from: Kimo Jesus on June 06, 2010, 08:16:31 am
for polyethene only 1 type of monemer

for nylon , 2 types of monomers , diamine and dicarboxylic acid (so i prefer to call this the repeating unit of nylon )

Oh k, thanks, :)
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Offline rameeziiii

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2672 on: June 06, 2010, 08:27:12 am »
hi?
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2673 on: June 06, 2010, 08:27:46 am »
help anyone
What volume of carbon dioxide is produced by burning 90 g of ethane in air?
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Offline Hesham Mhd

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2674 on: June 06, 2010, 08:28:04 am »
Guys, can someone explain the content of section 6.2 in the chemistry syllabus? bcuz i rlly dont get anything from it o.o' , Thank You =]
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2675 on: June 06, 2010, 08:31:31 am »
is it 144 dm3?
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2676 on: June 06, 2010, 08:32:41 am »
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elemis

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2677 on: June 06, 2010, 08:39:35 am »
Quote from: Nidzzz on June 06, 2010, 08:27:46 am
help anyone
What volume of carbon dioxide is produced by burning 90 g of ethane in air?

C2H6 + 3.5O2 -------->  2CO2 + 3H2O

After you form the above equation do this:

90g / (24+6) = 3 moles of ethane

2*3 moles = 6 moles of CO2 (using the molar ratio)

6*24 = 144 dm3
« Last Edit: June 06, 2010, 08:44:14 am by Ari Ben Canaan »
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2678 on: June 06, 2010, 08:41:32 am »
u forgot to balance the O2 in the equation , but u didnt nned it anyway


and yeah thats how  u do it NIdzz ^
« Last Edit: June 06, 2010, 08:44:29 am by Ari Ben Canaan »
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NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

elemis

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2679 on: June 06, 2010, 08:45:56 am »
Quote from: Kimo Jesus on June 06, 2010, 08:41:32 am
u forgot to balance the O2 in the equation , but u didnt nned it anyway


and yeah thats how  u do it NIdzz ^

I balanced it correctly on the rough paper I had; I was in a rush so I missed it out whilst typing  :-[

I removed the quote from your post so Nidzzz doesnt get confused, is that alright ?
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2680 on: June 06, 2010, 08:47:21 am »
yea sure np

good luck 2mrw !
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NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
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Offline rameeziiii

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2681 on: June 06, 2010, 08:48:34 am »
good luck....pray for me too.... i'm a disaster... i finished the lost symbol yesterday...lol
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Offline mdwael

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2682 on: June 06, 2010, 08:49:08 am »
I got 2 questions if someone knows atleast one im glad to have the answer. Ok so extracting aluminium, after the aluminium froms and O2 forms up it reacts with the carbon electrodes so they need to be replaced, but what confuses me is why are the electrodes made of carbon in the first place? why not something which wouldnot react with the oxygen? ???
and the second question is not really a question but im confused, what are the carbon chain lengths of the oil fractions seperated by fractional distillation, each one has a different carbon chain length but I got 2 text books and the teachers notes and they all give different carbon chains, so which one should I study for the IGs? ???
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elemis

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2683 on: June 06, 2010, 08:49:23 am »
Quote from: Kimo Jesus on June 06, 2010, 08:47:21 am
yea sure np

good luck 2mrw !

Thanks. Good Luck to you to ;)
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elemis

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2684 on: June 06, 2010, 08:51:57 am »
@mdwael  The electrodes used have to be unreactive right ? Now remember this is an industrial process, you cant use platinum because its too expensive and many other metals would melt at 900 deg c.

So carbon is cheap and a good conductor.


You dont need to memorise the carbon chains for the exam - just the names of the fractions and their uses.
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