Edexcel Chemistry Unit 1 IAL (WCH01) Core principles of chemistry - 23rd May 2014 Watch

ybadri
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#81
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what dd u write for why the bond energy for cl-cl bond greater than for f-f bond?
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Vivekmaj
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(Original post by saifulahmed)
for orbital i think the third one will be 8 or 16.
for the rest i hope they are correct cause i got the same answers.
No! the one of n=3 has two ways to get, you can use the formula 2n^2 or add the subshells (S+P+D) EITHER WAY YOU GET 18 as those are the max no of electrons if however they stated that it follows the octet rule then your answer of 8 would be correct
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Vivekmaj
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(Original post by ybadri)
what dd u write for why the bond energy for cl-cl bond greater than for f-f bond?
I only answered the question where it asked why F-F bond has a higher bond enthalpy, the one where the question was vice versa made me blank and i had no clue
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Fattyma97
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So is it 8 or 18?

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Fattyma97
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(Original post by Vivekmaj)
I only answered the question where it asked why F-F bond has a higher bond enthalpy, the one where the question was vice versa made me blank and i had no clue
Sameeee they can't make us contradict ourselves

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Vivekmaj
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(Original post by Fattyma97)
So is it 8 or 18?

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18
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koko1234
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(Original post by Fattyma97)
Sameeee they can't make us contradict ourselves

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Me too!!
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Ripper Phoenix
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lmao i just googled it and F-F is weaker than Cl-Cl... they say because of some repulsions..come on guys google it!!!
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Ripper Phoenix
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even though i wrote something diff in the exam paper!
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Ripper Phoenix
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(Original post by noosh_s)
could someone make an unofficial mark scheme please???
it would be difficult! there were too many questions lol .. going to see my tuition teacher soon so will clarify all doubtts!
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isam nazer
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what is the answer of the question about the E and Z ismoers ?
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hhalai96
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for the mean bond enthalpy .. was the answer suppose to be +416 or - ??
lattice enthalpy = -1046
for he h20 thing = -77
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hhalai96
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(Original post by Vivekmaj)
I only answered the question where it asked why F-F bond has a higher bond enthalpy, the one where the question was vice versa made me blank and i had no clue


i wrote F-F has a shorter bond hence more force of attraction compare to CL-Cl bond which is longer ...
for the next question i was blank toooo...
and in that same question the last one where it says why F-F bond don't require UV ... is it fine if you write fluorine is more reactive than chlorine
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Fattyma97
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I wrote that too!!! Btw, I really hope the grade boundaries aren't too high for an A what do u think they will be
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Ripper Phoenix
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(Original post by Fattyma97)
I wrote that too!!! Btw, I really hope the grade boundaries aren't too high for an A what do u think they will be
well tbh jan 14 was easy and the boundary was 58 .. now for this paper.. it was tricky and goood.. so i am expecting a 60 mark for the A.. what do u think?
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Ripper Phoenix
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Bond energy (in kJ/mol)

F-F:158
Cl-Cl: 244
Br-Br-:193
I-I: 151

Hence, in order of decreasing bond strength:
Cl-Cl => Br-Br => (F-F) => I-I
Fluorine is an anomaly.

Bond strength decreases from chlorine to iodine as down the group, the atomic size becomes larger and thus the valence electron orbitals become more diffused, causing the overlap of orbitals to become less effective. Therefore the halogen-halogen bond becomes weaker from chlorine to iodine.

Fluorine is an exception due to its extremely small size. The F-F bond length is so short that the lone pairs of electrons on the fluorine atoms repel each other and weakens the F-F bond.

I hope that answers your question.
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Fattyma97
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(Original post by Paras Agarwal)
well tbh jan 14 was easy and the boundary was 58 .. now for this paper.. it was tricky and goood.. so i am expecting a 60 mark for the A.. what do u think?
Some people are saying it will be 62-65, don't u think that's a little too high? I think 60 is reasonable not higher. :no:

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avishyaa
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what do you guys think the grade boundaries will be for an A?
Because if many people find it tricky, the grade boundaries could always go to a 56-58 as well. It just depends on the overall performance
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avishyaa
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also guys, can someone link me to the Edexcel Biology IAL that happened on 21st may??
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Ripper Phoenix
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(Original post by avishyaa)
also guys, can someone link me to the Edexcel Biology IAL that happened on 21st may??
http://www.thestudentroom.co.uk/show...el+ial+biology

thats the thread but not much was discussed..
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