Wooo yay if i specified dilute h2so4 can rite?
For question 4c, could you show us your answer? And 4di I wrote hbond with aspartic 4dii, vdw with tyrosine, is it correct?
Originally posted by Alohamadda:Wooo yay if i specified dilute h2so4 can rite?
Wooohoo for 3d(i) what do they mean by usual valency?
Originally posted by alycx:For question 4c, could you show us your answer? And 4di I wrote hbond with aspartic 4dii, vdw with tyrosine, is it correct?
Originally posted by Alohamadda:Wooohoo for 3d(i) what do they mean by usual valency?
Originally posted by UltimaOnline:
Alohamadda, yes you're right, it needs to be "excess". No need to specify "ethanol", just "alcohol" will do. In fact, many students didn't even mention ethanolic/alcoholic solvent. These students may or may not be penalized (Cambridge Mark Scheme does vary a little between different years).
That's bull. "Excess" isn't an important requirement.
For Qn 1c) can I say pka for h2o2 is lower cos it is stabilized by INTRAmolecular hydrogen bond? Also, can I say pka got CH3CO3H is higher cos of the electron donating OH group attached to the O atom?
Qn 4aii) can I just say cos Cl- electron donating (with elaboration) and showing the dissociation of both acids using equations. Will I get the full credit? I also briefly explained that there are carboxylate acids cos resonance stabilized(due to 2 O atoms bla bla)
Qn 4d) since both qns are 1m I just say like... For di) I say is tyrosine, Hydrogen bond
Dii) valine, VDW. Only like that cos I see is 1m... Do I need to say other types of bondings also or just say one for one part will suffice
oh no. what if i forgot to put "reflux" but just said heat...
Originally posted by Kingweixian:For Qn 1c) can I say pka for h2o2 is lower cos it is stabilized by INTRAmolecular hydrogen bond? Also, can I say pka got CH3CO3H is higher cos of the electron donating OH group attached to the O atom?
Qn 4aii) can I just say cos Cl- electron donating (with elaboration) and showing the dissociation of both acids using equations. Will I get the full credit? I also briefly explained that there are carboxylate acids cos resonance stabilized(due to 2 O atoms bla bla)
Qn 4d) since both qns are 1m I just say like... For di) I say is tyrosine, Hydrogen bond
Dii) valine, VDW. Only like that cos I see is 1m... Do I need to say other types of bondings also or just say one for one part will suffice
Originally posted by zzzzzzzz12345678765432:oh no. what if i forgot to put "reflux" but just said heat...
Hi Sir,For 4ai) Can i say the cl atom is electron withdrawing.hence it reduces the negative charge on the O atom of the conjugate base?
Originally posted by Soft&Wet:Hi Sir,For 4ai) Can i say the cl atom is electron withdrawing.hence it reduces the negative charge on the O atom of the conjugate base?
Eh sorry say wrong is electron withdrawing haha... Kk
Hi, may i ask if anyone knows whats the percentage of our practical exam and how much can it help in pushing a overall B to A?
and does anyone know what's the real reason pKa of H2O2 is lower and peroxyethanoic acid is higher? lol totally didn't have any idea of what to write.. are we even supposed to know this
Originally posted by Adelineeeee (::Hi, may i ask if anyone knows whats the percentage of our practical exam and how much can it help in pushing a overall B to A?
I think practical (excluding planning) is 15%, planning is 5%, then theory 80%. I think haha at least that's how we count for common tests in my school :)
3ciii is c=c=c. he was talking about 3civ
guys whats ur answer for 3bi,2diii, 3di,3dii tq
2diii I think L is chiral M is not
why ah?
Guys what's your structures of S & T for 3(d) how to draw?
Actually for M right... I not sure cos my school never teach sia.. Is it must reduce the ester? I tried reducing the ester and my formula tally... Some more it really did show one has chiral carbon another don't have
ya reduced ester. why u choose L though? how u find the paper?
M should be mah coz u see u form alcohol at both ends and 2 substituents are the same and followed by one oh and another h on the carbon