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Author Topic: Chemistry Help HERE ONLY !!  (Read 107293 times)

nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #660 on: May 31, 2009, 04:31:22 pm »
Quote from: ADi...M on May 31, 2009, 04:21:55 pm
hahaha nid,,
answered both of themm

was abt to do that..
lol.. :)

but i already did :P
i'm faster :P :P
gtg now..im so totally hungry....chemical reactions in my stomach are causing physical movements and dragging me to the diner table..lol :D

@ aquarian93 it's Fe2(2Fe is 56x2=112g)
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Offline Ghost Of Highbury

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Re: Chemistry Help HERE ONLY !!
« Reply #661 on: May 31, 2009, 04:33:03 pm »
lol...send some food here too...haha...lol!!
 :D :D :D
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divine intervention!

Offline aquarian93

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Re: Chemistry Help HERE ONLY !!
« Reply #662 on: May 31, 2009, 04:35:48 pm »
@nid: ohhhh! so dey want the % of iron in the rust, stupid me!
thank youu :)
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #663 on: May 31, 2009, 04:39:09 pm »
umm can any1 help me with question 7bii) in oct/nov 2007. its about tht excess stuff, plz i really need to know how substances are in exces

Thanks
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Offline archangel

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Re: Chemistry Help HERE ONLY !!
« Reply #664 on: May 31, 2009, 04:41:39 pm »
heyyyy....

i need help and May June 06 q.6

The radioactive isotopes!
help help help
i have 9 more hours before exams  ???
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Q80BOY

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Re: Chemistry Help HERE ONLY !!
« Reply #665 on: May 31, 2009, 04:50:21 pm »
Quote from: archangel on May 31, 2009, 04:41:39 pm
heyyyy....

i need help and May June 06 q.6

The radioactive isotopes!
help help help
i have 9 more hours before exams  ???

Radioactive Isotopes:

uses:

Medical (CIGS - cigarettes  :P)

C Cobalt Co 60 - Inaccessible cancer
I Iodine I 131 - Thyroid
G Gamma Rays - Sterilising
S Strontium Sr 90 - Skin cancer

IndUStrial

Uranium U 235 - nuclear power
Strontium Sr 90 - thickness of paper

hope i helped  :)
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Offline archangel

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Re: Chemistry Help HERE ONLY !!
« Reply #666 on: May 31, 2009, 05:01:12 pm »
Quote from: Q80BOY on May 31, 2009, 04:50:21 pm
Quote from: archangel on May 31, 2009, 04:41:39 pm
heyyyy....

i need help and May June 06 q.6

The radioactive isotopes!
help help help
i have 9 more hours before exams  ???

Radioactive Isotopes:

uses:

Medical (CIGS - cigarettes  :P)

C Cobalt Co 60 - Inaccessible cancer
I Iodine I 131 - Thyroid
G Gamma Rays - Sterilising
S Strontium Sr 90 - Skin cancer

IndUStrial

Uranium U 235 - nuclear power
Strontium Sr 90 - thickness of paper

hope i helped  :)

ahhh thank youuu so much =)

+rep

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Q80BOY

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Re: Chemistry Help HERE ONLY !!
« Reply #667 on: May 31, 2009, 05:02:43 pm »
thanks  :)

(i think u might have confused the +REP with the -REP button  :P or maybe it wasnt u  :-\)
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #668 on: May 31, 2009, 05:06:15 pm »
really, i need help with the question of excess stuff in, oct/nov2007 Q(7bii)

really need to know how to do it. ??? :'( :-[
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one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline Ibiza279

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Re: Chemistry Help HERE ONLY !!
« Reply #669 on: May 31, 2009, 05:10:35 pm »
Quote from: Shogun on May 31, 2009, 05:06:15 pm
really, i need help with the question of excess stuff in, oct/nov2007 Q(7bii)

really need to know how to do it. ??? :'( :-[

sure ill help ya though i dn knw the question its smewhere in the pile of books but i hv dne the paper so if ya tell me the question ill help ya out :)
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Offline heat619

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Re: Chemistry Help HERE ONLY !!
« Reply #670 on: May 31, 2009, 05:18:56 pm »
Is the pressure for the Contact Process 10 atm or 20 atm, cuz the mark scheme says 10 but the book says 20 :S
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #671 on: May 31, 2009, 05:24:25 pm »
here it is

(ii)one piece of marble 0.3g, was added to 5cm3 of hydrochloric acid, concentration 1.00 mol/dm3. which reagent is in excess? give reason for your answer.

mass of one mole of CaCO3 =100g

number of moles of CaCO3= .................................................................
number of moles of HCl=.......................................................
regent in excess is ...........................................................
reason....................................................................
                                                                                                   [4]

(iii) use your answer to (ii) to calculate the maximum volume of carbon dioxide produced measured at r.t.p.
...[1]

explain to me what u have to do, plz dont just give me the answer, do explain every part on how to find the excess.

Thanks
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one who masters both the pen and paper is indeed a true warrior.

\m/metal head\m/

Offline Ibiza279

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Re: Chemistry Help HERE ONLY !!
« Reply #672 on: May 31, 2009, 05:26:06 pm »
Quote from: heat619 on May 31, 2009, 05:18:56 pm
Is the pressure for the Contact Process 10 atm or 20 atm, cuz the mark scheme says 10 but the book says 20 :S

huh we learnt it was 1 atp not 10 or 20 n i checked wikipedia too they say its 1-2 atp so the rite answer is 1 atmospheric pressure
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Offline thukon

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Re: Chemistry Help HERE ONLY !!
« Reply #673 on: May 31, 2009, 05:31:13 pm »
@shogun. CaCO3= 40+12+16+16+16= 100
Number of moles of CaCO3 = 0.3/100= 0.003
Number of moles of HCL = 1 mol per dm3, and 1000cm3 = 1 dm3. 5/1000= 0.005
The reaction needs 1 mol of CaCO3 and 2 mols of HCl. So the HCl needs to be double the the CaCO3, but here there isnt enough, because the CaCO3 is 0.003, and the HCl needs to be 0.006, but its only 0.005. So CaCO3 is in excess.

I was kinda confused myself doing the question. Check with the mark scheme and tell me if im correct. If i am, +rep me PLZ. I REALLY NEED IT!!
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Offline XGhostX

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Re: Chemistry Help HERE ONLY !!
« Reply #674 on: May 31, 2009, 05:32:36 pm »
People i have found this site .....Hope its useful..... http://www.chemactive.com/grade_10.html  :P
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XD
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