Chemistry P4| A2 only

[angelgirl:)]

Na test is just for -OH or its for -OH,-COOH, and -C=O?

 

[smzimran]

bt how???
wel i have a cnfusion.......whenver we do an electrophilic substitution ......only hyddrogen gets substituted.......is there any possibilty that one of the substituents like chlorine myt also get substituted?

In benzene ?
No because C-Cl bond is way more stronger than C-H bond!

 

[smzimran]

Na test is just for -OH or its for -OH,-COOH, and -C=O?

Not for C=O

Na reacts with carboxylic acid and alcohols

 

[Pratik.Dhakal]

can some one provide me worksheets based on polymerization ??

 

[angelgirl:)]

Not for C=O

Na reacts with carboxylic acid and alcohols

but in my note i wrote its just for -oh....

 

[smzimran]

but in my note i wrote its just for -oh....

Wait lemme confirm!

 

[smzimran]

Na test is just for -OH or its for -OH,-COOH, and -C=O?

Well,
Na reacts with:
1. carboxylic acid
2. alcohol
3. phenol

100% confirm!

 

[user]

Aoa wr wb!

Remember this way:

alcohol
reacts with Na

phenol
reacts with Na and bases

carboxylic acid
reacts with Na,bases and carbonates

 

[smzimran]

Briefly explain why the benzene molecule is planar?
Briefly explain why all the carbon-carbon bonds in benzene are the same length?
why is length of carbon-carbon bond in benzene different from simple carbon-carbon sigma bond?+
one cnfusion....according to kekule structure ....benzene wud still be planar molecule ryt????
the only problem wud be differing carbon-carbon bond lengths ....m i ryt???

- It is planar because it forms 3 sigma bonds and the fourth bond is pie bond, we do not take pie bond in consideration when considering bond angles!

- All C-C bonds are equal in length due to delocalisation of pie bond.

- C-C bond length is different from aliphatic chain because of the effect of the delocalised pie bond!

- Yes, u r right about the Kekule structure thing!

 

[user]

- It is planar because it forms 3 sigma bonds and the fourth bond is pie bond, we do not take pie bond in consideration when considering bond angles!

- All C-C bonds are equal in length due to delocalisation of pie bond.

- C-C bond length is different from aliphatic chain because of the effect of the delocalised pie bond!

- Yes, u r right about the Kekule structure thing!

aoa wr wb! what's kekule

 

[hassam]

well i learnt its planar cos for sideways p-p overalp....it cn only occur if its planar.....

 

[smzimran]

aoa wr wb! what's kekule

See attachments,
I dont know why i am having a problem posting full size image here!

Read this also:
http://www.chemguide.co.uk/basicorg/bonding/benzene1.html

 

[hassam]

well the molecule of PEG denies ms point that there must be two different functional groups present for condensation polymerization to occur ......isnt it?
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_41.pdf
q10 e,....arent the last two ms points essentially the same thing.....
and in d part (i)why only OH attched drug......coos hydrogen bond cn also be formed by ether like O in the centre ...????

 

[angelgirl:)]

Well,
Na reacts with:
1. carboxylic acid
2. alcohol
3. phenol

100% confirm!

thanks alooot...

 

[hassam]

well smzimran.....whenever asked what is order of rxn ms always says power to which concentration of reactant is raised to in the rate quation.....isnt it order w.r.t to particular reactant....i find this definition inappropriate

 

[smzimran]

well smzimran.....whenever asked what is order of rxn ms always says power to which concentration of reactant is raised to in the rate quation.....isnt it order w.r.t to particular reactant....i find this definition inappropriate

Yes to be on the safe side, mention that
Order of reaction w.r.t to a reactant is..........

But the m.s definition is also correct because they are referring to order of reaction in general, not being specific to any particular reactant

 

[hassam]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_42.pdf
see question 2 part b ii.....now thats relating to gibbs free energy equation.....and we are not supposed to knw that stuff,,,,
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_ms_42.pdf
q3 part a
even if sf4 was symmetrical it wud have a dipole so i dont agrreee with ms saying its symmetrical .....only lone pair explanation shud be allowed....correct me if i am wrong

 

[zenyatales]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_4.pdf
how do you do question 8 b?
thanks for the help!

 

[user]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_42.pdf
see question 2 part b ii.....now thats relating to gibbs free energy equation.....and we are not supposed to knw that stuff,,,,,plus...i dun get ms.....temp/enetropy change reamins constant.......temperature of WHAT?.....cos we have been give lattice energies and enthalpy changes of hydrations only.....so which temp. is he referring to

what i think is....solubility depends on temperature..right? so in that sense...it says temperature same

 

[smzimran]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_42.pdf
see question 2 part b ii.....now thats relating to gibbs free energy equation.....and we are not supposed to knw that stuff,,,,,

Whats that ?
It can be solved by considering the equation:
enthalphy change of solution = enthalphy change of hydration - enthalpy change of lattice
hassam: