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Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 268466 times)

Offline Assi1993

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1305 on: June 14, 2011, 09:27:09 pm »
can some1 tell me that how is D the answer?
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Offline guMnam

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1306 on: June 14, 2011, 10:18:17 pm »
Quote from: Assi1993 on June 14, 2011, 09:27:09 pm
can some1 tell me that how is D the answer?
change is 3 (tripled) and the sum of orders is 1 + 2 = 3

therefore

31+2=27
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1307 on: June 14, 2011, 10:29:03 pm »
Quote from: Assi1993 on June 14, 2011, 09:27:09 pm
can some1 tell me that how is D the answer?
Hope image is clear. :)
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Offline Assi1993

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1308 on: June 14, 2011, 10:40:02 pm »
thanku u both <3 :) !
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1309 on: June 14, 2011, 10:49:12 pm »
Quote from: Assi1993 on June 14, 2011, 10:40:02 pm
thanku u both <3 :) !

Welcome!
Can you PLEASE help me with Q18ciii&iv from the sample paper?!
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Offline Assi1993

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1310 on: June 15, 2011, 12:02:02 am »
i dont know either :( !! @ rumeesa....

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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1311 on: June 15, 2011, 12:19:22 am »
Quote from: Assi1993 on June 15, 2011, 12:02:02 am
i dont know either :( !! @ rumeesa....



=(

I guess no one knows! I tried asking everyone! :(
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1312 on: June 15, 2011, 01:17:59 am »
Magnesium is used as mass rather than the HCl because HCl is in excess and magnesium is the compound that reacts fully.
« Last Edit: June 15, 2011, 01:19:55 am by Romeesa Chan »
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Offline HUSH1994

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1313 on: June 15, 2011, 04:30:38 am »
The concentration of the acid would not affect the amount of H2 gas produced.If there is excess hydrochloric acid, the reaction goes until all the magnesiumis used up and then stops. The reaction might be more vigorous if the acid is more concentrated, but when one or the other of the reactants is used up, the reaction will stop.If the acid were so dilute that the HCl is used up before all the magnesium, the
amount of hydrogen produced is less than if there were excess HCl. That's due to the fact that the HCl is now the limiting reactant and when it's all used up,the reaction stops, even if there is still unreacted magnesium.
About the question in the attachment,can please post the link for the past paper so i check it :)
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1314 on: June 15, 2011, 06:19:40 am »
Quote from: The Joker|HUSH on June 15, 2011, 04:30:38 am
The concentration of the acid would not affect the amount of H2 gas produced.If there is excess hydrochloric acid, the reaction goes until all the magnesiumis used up and then stops. The reaction might be more vigorous if the acid is more concentrated, but when one or the other of the reactants is used up, the reaction will stop.If the acid were so dilute that the HCl is used up before all the magnesium, the
amount of hydrogen produced is less than if there were excess HCl. That's due to the fact that the HCl is now the limiting reactant and when it's all used up,the reaction stops, even if there is still unreacted magnesium.
About the question in the attachment,can please post the link for the past paper so i check it :)

Thank youuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu, senpai! :D

http://www.edexcel.com/migrationdocuments/GCE%20New%20GCE/sam-gce-chemistry.pdf

It's Unit 4- hope you find it! ;)
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Offline HUSH1994

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1315 on: June 15, 2011, 06:34:44 am »
Quote from: Romeesa Chan on June 14, 2011, 10:49:12 pm
Welcome!
Can you PLEASE help me with Q18ciii&iv from the sample paper?!
These parts?
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1316 on: June 15, 2011, 07:32:35 am »
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Offline HUSH1994

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1317 on: June 15, 2011, 08:19:39 am »
sorry but both parts look quite complicated,i never studies anything like that before(not in the AS),its looks quite challenging :O, anyway can you please link it to its mark scheme,i might get something from there ;)
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1318 on: June 15, 2011, 08:24:09 am »
Quote from: The Joker|HUSH on June 15, 2011, 08:19:39 am
sorry but both parts look quite complicated,i never studies anything like that before(not in the AS),its looks quite challenging :O, anyway can you please link it to its mark scheme,i might get something from there ;)


It's alright if you can't. I appreciate that you even tried.

I know. The thing is, I've not seen such a question EVER either. Part c iii- I don't understand the mass calculation.
We used moles of Mg initially but then for temperature change, we used HCl. I don't get that.

Part civ I don't understand the time thingy.

The mark scheme is at the end of the link I gave previously. ;)
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Offline HUSH1994

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1319 on: June 15, 2011, 08:34:16 am »
in part iii) the mass is 100,you have to use the mass\volume in cm^3 of the liquid\solution reacting.
ill take a look at the mark scheme and tell you if i got anything ;)
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