Originally posted by Thomas00:Ultima, which questions u find more time consuming?
Is the percentage by mass 44%? And for the cell diagram is it O2 on one side and methane gas on the other?
Yes (but you should give to 3 sig fig) and yes (labeled with standard pressures of 1 bar or 1 atm).
Originally posted by UltimaOnline:
Q1 & Q3.Yes (but you should give to 3 sig fig) and yes (labeled with standard pressures of 1 bar or 1 atm).
Ok thanks :)
Originally posted by ArJoe:Hi just asking for qn 5 will there be ecf? So if i used disubstituted bromine and disubstituted amine in the next product, will they mark the amine part correct?
Originally posted by UltimaOnline:
No guarantees. For purpose of estimating your own marks, better play safe and assume no error carried forward.
Originally posted by ArJoe:
For the energy cycle question, if you sub in all the correct values, correct substances, butyou drew bond energy arrow in the opposite direction, how many marks can be awarded?
Anyone managed to find K for question 3 ? K was damn hard to find
Originally posted by theophilus:Anyone managed to find K for question 3 ? K was damn hard to find
If i am not wrong, theres intramolecular bonding which would consist of the double bonds needed to form H
Originally posted by Thomas00:Ultima, which questions u find more time consuming?
Is the percentage by mass 44%? And for the cell diagram is it O2 on one side and methane gas on the other?
I would think the CO2 should be a gas also. some people might choose to dissolve it in aqueous just like your coke but co2 should not be able to dissolve to hit 1moldm3
Originally posted by Nomkla:If i am not wrong, theres intramolecular bonding which would consist of the double bonds needed to form H
Im talking about Question 3dii the deduction question find K. The K formula is C12H12 how come got hydrogen bond all one :O ??
Originally posted by UltimaOnline:
No worries about state symbols.
Hmm so I won't be penalised for writing wrong state symbols?
Originally posted by theophilus:Im talking about Question 3dii the deduction question find K. The K formula is C12H12 how come got hydrogen bond all one :O ??
It is hard to explain without the aid of an image. But basically it is methyl benzene with CH=CH-CH=C(CH3). Then the =CH-CH= will undergo oxidative cleavage to form H.
Originally posted by Zhhh_:Hmm so I won't be penalised for writing wrong state symbols?
Originally posted by theophilus:Anyone managed to find K for question 3 ? K was damn hard to find
I'll let someone else (preferably a student) reveal the structure of K here.
Haha, though its quite interesting they set something like this, considering E came out almost 5 times and FRS was also repeated...
Most students would agree the paper was very easy and for the meticulous and careful one
Overall, it does seem like this is the last year of the old syllabus so perhaps they yoloed for almost all of the subjects
Good luck though for math and econs and bio and phy!
Also for the people who want to verify, the bond energy should be 202 (if im not mistaken)
Originally posted by Thefire521:Haha, though its quite interesting they set something like this, considering E came out almost 5 times and FRS was also repeated...
Most students would agree the paper was very easy and for the meticulous and careful one
Overall, it does seem like this is the last year of the old syllabus so perhaps they yoloed for almost all of the subjects
Good luck though for math and econs and bio and phy!
Also for the people who want to verify, the bond energy should be 202 (if im not mistaken)
Originally posted by ArJoe:
hey, if i got that value but in -, and i got everything else in the question correct, except arrows in wrong direction, can i get at least 3 marks.... and the mechanism to be drawn is electrophilic sub right??
Usually (like in prelims and school exams), teachers only minus 1/2 mark for final answer but give you the rest for the cycle and ECF. So yes and yes.
But then the important thing is you should ask yourself why that mistake was made - students nowadays probably blindly memorise energetics without realising that "bond energy is the energy needed to break" -i am sure so many of you would have made this mistake that they would probably go lenient on this one lol
Hi!
Many ppl in my sch found the paper easy. So I don't think the mark boundary will actually be that low... right?
Also, what's the pKa value for question 1? :)
Originally posted by zenthyl:Hi!
Many ppl in my sch found the paper easy. So I don't think the mark boundary will actually be that low... right?
Also, what's the pKa value for question 1? :)
Got pKa meh?
Oops, I mean Kp!
I was really sleepy during the paper again lmao. Btw for the bond energy qn i misread the qn and drew 2 energy cycle instead. Which means i drew energy cycle of the reactants relating to their gas phase atoms and product relating the their gas phase atom. So obviously i couldn't find the bond energy of br-f. Will i still get some marks tho? for qn4 they asked us to draw diagrams where appropriate, will i get penalized if i didn't draw any?
Originally posted by AwkwardPotato:I was really sleepy during the paper again lmao. Btw for the bond energy qn i misread the qn and drew 2 energy cycle instead. Which means i drew energy cycle of the reactants relating to their gas phase atoms and product relating the their gas phase atom. So obviously i couldn't find the bond energy of br-f. Will i still get some marks tho? for qn4 they asked us to draw diagrams where appropriate, will i get penalized if i didn't draw any?
0 for the energy cycle since that is an entire misreading of the question.
As for question 4, usually some marks are allocated for the diagram. (e.g hydrogen bond diagram), therefore if you never draw then you need to have explained it so splendidly that they can understand without even looking at the diagrams.