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Chemistry P1 Challenging Questions Preparation

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1ajia1

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fishcook said:
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q10?

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf
Q7
Please help
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for q10:
Explaining the terms
Bond dissociation enthalpy and mean bond enthalpy
Simple diatomic molecules
A diatomic molecule is one that only contains two atoms. They could be the same (for example, Cl2) or different (for example, HCl).
The bond dissociation enthalpy is the energy needed to break one mole of the bond to give separated atoms - everything being in the gas state.
Important! The point about everything being in the gas state is essential. You cannot use bond enthalpies to do calculations directly from substances starting in the liquid or solid state.
As an example of bond dissociation enthalpy, to break up 1 mole of gaseous hydrogen chloride molecules into separate gaseous hydrogen and chlorine atoms takes 432 kJ. The bond dissociation enthalpy for the H-Cl bond is +432 kJ mol-1.
so u need enthalpy change of atomisation.
 
Mayedah

Mayedah

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sandrawrr said:
Answer : D
If you can't read my handwriting sorry:
The "H" from NH3 and "Br" from the other molecule get removed( something like condensation)
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Oh my Thankyou soo much :D
but i would have never thought abt this in the first place actually and whts the reason for rejection to options A and B ?
 
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sandrawrr

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fishcook said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_12.pdf
Q10 why is it b and not c?
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for option "C"( sort of correct): Cl is more electronegative so C moves towards Cl -->.. and O is more electronegative compared to C so C's dipole moves towards <--.. But this is still a polar molecule as "O" is more electronegative compared to C.. hence having a dipole
Answer is "B" because they asked for LARGEST overall dipole.. The overall dipole for this is <---- which is greater than compound "C"
 
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sandrawrr

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1357911 said:
/O/N/11 varient 11 q-2 and q-9
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Q2) PbCl4 + 4NaBr -> 4NaCl+ PbBr2 + Br2

Find the moles of PbCl4 which is 6.980/R.F.M of PbCl4

The react 1:1 ratio therefore Moles of PbCl4 x (79.9x2) = Mass of Br2 which option C
 
1357911

1357911

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Im sorry. I didnt undrstand the equation. How come its PbBr2 + Br2
 
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