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Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 254125 times)

Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1530 on: December 09, 2011, 05:08:10 pm »
Quote from: jackfos92 on December 09, 2011, 01:05:36 pm
is phenol soluble in ethanoic acid?

if yes, is it more soluble than water?

Not sure about it's solubility in Ethanoic acid.

But, Phenol is moderately soluble in water - about 8 g of phenol will dissolve in 100 g of water.

If you try to dissolve more than this, you get two layers of liquid. The top layer is a solution of phenol in water, and the bottom one a solution of water in phenol. The solubility behaviour of phenol and water is complicated, and beyond A level.

Phenol is somewhat soluble in water because of its ability to form hydrogen bonds with the water.
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Offline ~ Miss Relina ~

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1531 on: December 09, 2011, 10:19:35 pm »
plz answer me

is the question attached is neded by our Edxecel syllabus ...........????

need reply soon as my exams are toooooo close  :-\
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Offline MKh

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1532 on: December 10, 2011, 02:51:33 pm »
Quote from: ~ Miss Relina ~ on December 09, 2011, 10:19:35 pm
plz answer me
is the question attached is neded by our Edxecel syllabus ...........????
need reply soon as my exams are toooooo close  :-\

I m not really sure but, as far as i know, Raoult's Law is not required by our new Edexcel GCE Chemistry specification.

If u hav a marking scheme for this question, just hav a look at the answer for this question.
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1533 on: December 10, 2011, 04:29:39 pm »
Edexcel Unit 4 Acid and Base Equilibrium Question. => Tomorrow's MY Mock Exam !

Sometimes the concentration of the acid and base are NOT 1:1 and in such cases I don't know how to figure out the Equivalence Vloume.

Example :

when 0.20 M NaOH reacts with 0.10 M of Ch3COOH. the acid is 20 cm3 , Why does the Equivalence Volume is equal to 10 cm3 , why is it NOT 40 cm3 ?

if the ratio is 1 : 1 as in 0.1 M of NaOH and 0.1 M of Ch3COOH (volume of acid is 25 cm3 ) then equivalence Volume is 25 cm3 cuz they are 1:1 , same concentration that is.

My teacher said he'll make the concentrations different to trick us so I NEED ot know this BEFORE tomorrow since my exams is Tomorrow so PLEASE Help !

I'm asking this Question cuz I ALWAYS get the equivalence Volume WRONG when I draw the Titration Curve.

Thanks in Advance =D

[ I'll check this in a few hours from now cuz I need to study the rest of the Topics ]
« Last Edit: December 10, 2011, 04:34:34 pm by Sheikh Zayed Al Nahyan »
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1534 on: December 10, 2011, 04:54:42 pm »
Each titration curve is different.

The ratio of 1:1 is for strong acid and strong base.

Weak acid and strong base or weak base and strong acid will have a different curve therefore a different equivalence point.

Aren't they explained in the textbook ? :-\


PS- Check this site. :)
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1535 on: December 10, 2011, 05:01:00 pm »
I understand this fully Alhamdulilah =]

What I don't understand is how to determine the Equivalence Volume.

just like in the examples I gave =]
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Offline iluvme

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1536 on: December 10, 2011, 05:09:52 pm »
Its been drilled into our heads that even if the volumes are in a ratio of 1:1 but the concentration of the acid is double the concentration of the base, then the equivalence volume is halved.

As for your question, try using C1V1=C2V2.
« Last Edit: December 10, 2011, 05:21:57 pm by Jason Bourne »
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1537 on: December 10, 2011, 05:11:46 pm »
Never heard of that Equation :$

can you elaborate a bit :$ :$
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Offline iluvme

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1538 on: December 10, 2011, 05:14:07 pm »
(Concentration * Volume)acid=(Concentration * Volume)base
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1539 on: December 10, 2011, 05:16:03 pm »
We didn't take it but I'll surely be using it tomorrow =D  .. You're a LIFE Saver =D

Romeesa thanks By the way <3
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1540 on: December 10, 2011, 05:17:19 pm »
No problem.

But are you sure? Even if your teacher hasn't taught you about it?
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1541 on: December 10, 2011, 05:19:54 pm »
Yup , Well I'll try calling my friend now so that I can find an alternative but if I can't then well that's the only solution I guess  :-X :)
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Offline Romeesa-Chan

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1542 on: December 10, 2011, 06:03:25 pm »
Quote from: Sheikh Zayed Al Nahyan on December 10, 2011, 05:01:00 pm
I understand this fully Alhamdulilah =]

What I don't understand is how to determine the Equivalence Volume.

just like in the examples I gave =]

Honey, you see the titration curve, yes ?

Take the midpoint of the straight line. A horizontal line should be drawn to that midpoint to obtain the equivalence point.

Did you get it now ? (:
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Offline ~ Miss Relina ~

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1543 on: December 10, 2011, 08:27:45 pm »
attached why answer is C

 ??? ???
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1544 on: December 10, 2011, 08:29:30 pm »
Quote from: MKh on December 10, 2011, 02:51:33 pm
I m not really sure but, as far as i know, Raoult's Law is not required by our new Edexcel GCE Chemistry specification.

If u hav a marking scheme for this question, just hav a look at the answer for this question.


Thanks
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