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Author Topic: CHEMISTRY PAPER 1 HERE  (Read 37876 times)

Offline igexam

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Re: CHEMISTRY PAPER 1 HERE
« Reply #270 on: June 11, 2009, 07:34:25 pm »
right, but hcl is already present, isnt that acidic enough
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Offline sweetsh

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Re: CHEMISTRY PAPER 1 HERE
« Reply #271 on: June 11, 2009, 07:35:14 pm »
The answer is B
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Offline Triple_A

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Re: CHEMISTRY PAPER 1 HERE
« Reply #272 on: June 11, 2009, 07:36:30 pm »
look.....first.hcl is used up so pH increases then nitric acid forms so it decreases!!!
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Offline igexam

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Re: CHEMISTRY PAPER 1 HERE
« Reply #273 on: June 11, 2009, 07:37:54 pm »
but in the end, shudnt the ph remain the same?
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Offline sweetsh

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Re: CHEMISTRY PAPER 1 HERE
« Reply #274 on: June 11, 2009, 07:39:05 pm »
No the pH will decrease as they said..there;'s no option for the pH to be "the same"
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Offline GodOfWar

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Re: CHEMISTRY PAPER 1 HERE
« Reply #275 on: June 11, 2009, 07:39:47 pm »
lool no barium nitrate is in the test tube not HCl. You add HCl to it, its pH will decrease from i gess 7 around 2. And no ppt will be formed cuz the BaCl2 produced will dissolve .
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Offline igexam

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Re: CHEMISTRY PAPER 1 HERE
« Reply #276 on: June 11, 2009, 07:41:22 pm »
Oh!!!!!! yes, ur rite... barium is in the test tube. Thank you soo much
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Offline MR.BooMBastiC

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Re: CHEMISTRY PAPER 1 HERE
« Reply #277 on: June 11, 2009, 07:41:48 pm »
Quote from: Triple_A on June 11, 2009, 07:32:38 pm
Nope......pH will decrease (acidic) bec nitric acid forms!

YEAH...THAT ONLY I WAS THINKING..... :)
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Offline GodOfWar

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Re: CHEMISTRY PAPER 1 HERE
« Reply #278 on: June 11, 2009, 07:43:20 pm »
Quote from: Triple_A on June 11, 2009, 07:36:30 pm
look.....first.hcl is used up so pH increases then nitric acid forms so it decreases!!!
noh dude. nitric acid WONT be formed at all !!
 The equation goes like this:
     BaNO3 + 2HCl --> BaCl2 + H2O + NO2
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Offline GodOfWar

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Re: CHEMISTRY PAPER 1 HERE
« Reply #279 on: June 11, 2009, 07:46:21 pm »
Quote from: igexam on June 11, 2009, 07:41:22 pm
Oh!!!!!! yes, ur rite... barium is in the test tube. Thank you soo much

llol Thanks for the +rep . I'd been stuck on -5 for eternity  :-[
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Offline Triple_A

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Re: CHEMISTRY PAPER 1 HERE
« Reply #280 on: June 11, 2009, 07:46:37 pm »
Thanks 4 correcting! ;D
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Offline GodOfWar

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Re: CHEMISTRY PAPER 1 HERE
« Reply #281 on: June 11, 2009, 07:49:44 pm »
Quote from: Triple_A on June 11, 2009, 07:46:37 pm
Thanks 4 correcting! ;D

ur welcome  :)
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Offline simba

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Re: CHEMISTRY PAPER 1 HERE
« Reply #282 on: June 11, 2009, 07:50:27 pm »
will someone help me in quetion 4 ,15, and 37 in nov.08
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Offline VIP_93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #283 on: June 11, 2009, 07:52:31 pm »
can any 1 plz post chemistry past papers from 93 _ 95 and their mark scheme.

thanx in advance
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Offline VIP_93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #284 on: June 11, 2009, 07:59:20 pm »
4 _ A ,cuz X is ionic so is solube in water and is the filterate while Y is organic so solube in organic solvents and is in the filterate too

15 _ A , cuz when 5g of X REACT WID 1000 cm , 500cm only react while the excess 500 are used to warm the mixture so when 500cm of water only react wid 5g then then all the 500cm react and there is no excess to warm the mixture and raise the temperature so the the decrease will be double

37 _ C cuz an acid will react with the carbonate to give bubbles of CO2
hope this helps
good luck ;) ;)
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