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Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 268985 times)

Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1125 on: May 22, 2011, 03:53:22 pm »
Quote from: ang3l on May 22, 2011, 03:44:01 pm
Outline an experiment to demonstrate that catalyst is not used up in a reaction? (practical details not needed)

Thx

weigh the catalyst  using top loading balance
filter it back from the mixture after the reaction is complete
wash it with distilled water
dry it and then re-wiegh it
the Mass remains same (unchanged)

GG :)
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Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1126 on: May 22, 2011, 04:59:46 pm »
The question is about two isomeric halogenoalkanes, P and Q.
(a) A hot aqueous solution of silver nitrate is added to each halogenoalkane. Both
halogenoalkanes react to form a yellow precipitate.

(ii) The isomers have relative molecular mass 169.9. Deduce the molecular formula
of the isomers.


Ok how do we deduce it
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1127 on: May 22, 2011, 05:03:46 pm »
Quote from: Nidzzz on May 22, 2011, 04:59:46 pm
The question is about two isomeric halogenoalkanes, P and Q.
(a) A hot aqueous solution of silver nitrate is added to each halogenoalkane. Both
halogenoalkanes react to form a yellow precipitate.

(ii) The isomers have relative molecular mass 169.9. Deduce the molecular formula
of the isomers.


Ok how do we deduce it

Is it C3H7I ??
« Last Edit: May 22, 2011, 05:06:45 pm by Ari Ben Canaan »
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1128 on: May 22, 2011, 05:04:04 pm »
Quote from: Nidzzz on May 22, 2011, 04:59:46 pm
The question is about two isomeric halogenoalkanes, P and Q.
(a) A hot aqueous solution of silver nitrate is added to each halogenoalkane. Both
halogenoalkanes react to form a yellow precipitate.

(ii) The isomers have relative molecular mass 169.9. Deduce the molecular formula
of the isomers.


Ok how do we deduce it

It forms yellow ppt so its clear that it is iodide

Now tha rest has to be carbon and hydrgoen so 169.9 - 126.9 = 43
so u have to check how many carbon + Hydrogen can make up 43
three carbons make up 36 + 7 for hydrogen so that make up 43
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1129 on: May 22, 2011, 05:05:31 pm »
Quote from: Ari Ben Canaan on May 22, 2011, 05:03:46 pm
Is it C3H8I ??

not 8 H since if u have 8 H there is no room for I to add
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1130 on: May 22, 2011, 05:07:46 pm »
Quote from: Nidzzz on May 22, 2011, 04:59:46 pm
The question is about two isomeric halogenoalkanes, P and Q.
(a) A hot aqueous solution of silver nitrate is added to each halogenoalkane. Both
halogenoalkanes react to form a yellow precipitate.

(ii) The isomers have relative molecular mass 169.9. Deduce the molecular formula
of the isomers.


Ok how do we deduce it

R - I = 169.9

and you continue as ang3l mentioned ;)
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1131 on: May 22, 2011, 05:09:30 pm »
Quote from: ~ The Golden Girl ~ on May 22, 2011, 05:07:46 pm
R - I = 169.9

and you continue as ang3l mentioned ;)
lol..:P
Ready for 2morrow ?:D
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Offline The Golden Girl =D

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1132 on: May 22, 2011, 05:10:46 pm »
Quote from: ang3l on May 22, 2011, 05:09:30 pm
lol..:P
Ready for 2morrow ?:D

Yup , Good Luck ;)
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Offline NidZ- Hero

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1133 on: May 22, 2011, 05:20:42 pm »
The answer is C3H7I

THANKS EVERYONE
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1134 on: May 22, 2011, 05:50:49 pm »
Why series of readings are taken for temperature in enthalpy change experiment?
Do we just say that to allow for cooling
Or is that too vague?
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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1135 on: May 22, 2011, 06:51:14 pm »
Quote from: ang3l on May 22, 2011, 05:50:49 pm
Why series of readings are taken for temperature in enthalpy change experiment?
Do we just say that to allow for cooling
Or is that too vague?

you can say to allow for cooling or to compensate for heat loss.
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Offline ~ Miss Relina ~

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1136 on: May 22, 2011, 07:05:46 pm »
solubility of simple molecules in different solvents experiments
needed by syllabus and i donno anthig abt it
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Offline Malak

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1137 on: May 22, 2011, 07:24:17 pm »
Quote from: Relina on May 22, 2011, 07:05:46 pm
solubility of simple molecules in different solvents experiments
needed by syllabus and i donno anthig abt it
You basically just have to know that Polar molecules will dissolve in polar solvents and Non-polar in non-polar solvents.

Like Iodine will dissolve in hydrocarbon solvent but will be partially or insoluble in water
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Offline guMnam

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1138 on: May 22, 2011, 07:46:44 pm »
H-Cl bond is stronger than H-I bond... why ?

and do we have to learn uses of diferent polymers???
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Offline NightHawkerr

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Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #1139 on: May 22, 2011, 08:05:54 pm »
If the temperature increases what happens to the peaks( and the broadness) in the infrared spectroscopy? I had this question in my mock exam today, didn't know how to answer it. ;/
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