Post by: ashwin on June 10, 2010, 01:13:30 am
I put 0, as the protons bonded to the adjacent carbon atom are non-equivalent (different from the CH2 protons), so none are equivalent (in the same environment).
However, Mao's answer says 2. Can anyone clarify this please? (Question 2 d i).
Thanks
Post by: vexx on June 10, 2010, 01:19:14 am
its definitely 2.
Post by: Davoo! on June 10, 2010, 08:24:30 am
Post by: vexx on June 10, 2010, 02:56:53 pm
I got 2. I think it's the N+1 rule?
yep that's it.
Post by: nick5335 on June 10, 2010, 04:21:22 pm
Post by: monicapham93 on June 10, 2010, 05:13:53 pm
yet most people didnt pick up on this.
am i completley off?
Post by: Greggler on June 10, 2010, 05:19:09 pm
fuckn hell. dont know whether everyone's overthinking it or what. but this exam has just turned out to be the biggest bitch. I studied so much for it and if it ends up ive lost majority of my marks on stupid crap like this it'll piss me off. What'll piss me even more off is if i end up doing better for physics (which it looks like might be the case) when i did not study for physics and a absolute shitload for chem.
rawwwwwrrrrrrrrrrr
Post by: jimmy999 on June 10, 2010, 06:39:42 pm
Post by: kakar0t on June 10, 2010, 06:41:51 pm
Post by: amimery on June 10, 2010, 09:11:56 pm
because it previously states says
" the signal is split into a triplet"
why would they tell you that in the first place?
is it possibly an error on vcaas part?
Post by: kenhung123 on June 10, 2010, 09:24:43 pm
Post by: chem-nerd on June 10, 2010, 09:42:24 pm
It most likely you are not used to the chemistry wording of it. Its saying how many hydrogens in the same chemical environment adjacent to the hydrogen under investigation causes a triplet in NMR spectrum^^this
Post by: VeryCrazyEdu. on June 10, 2010, 09:47:55 pm
Post by: Lighties on June 10, 2010, 09:53:03 pm
I'm going to hope they mark both as right though =|
Post by: VeryCrazyEdu. on June 10, 2010, 10:00:23 pm
Post by: Lighties on June 10, 2010, 10:15:34 pm
Post by: Mao on June 10, 2010, 10:38:14 pm
"What is the number of equivalent protons bonded to the adjacent carbon atom?"
"equivalent proton" here refers to protons that are the same environment compared to each other. It is well established that the adjacent carbon atom is bonded to two H, and these two H are in the same, thus there are two equivalent protons bonded to the adjacent carbon.
If you have interpreted it the other way, the question would have read:
"What is the number of protons bonded to the adjacent carbon atom that are equivalent to the protons detected at
This question doesn't make logical sense. If the answer is more than 0, i.e. the carbon and H environments are equivalent, all of these protons will be found in the same peak at 1.3ppm, thus it will be referring to the adjacent carbon atom that is of a different environment. Hence the answer has to be 0, and the interpretation goes 'how many other protons outside of this peak is equivalent to this peak? 0 under all circumstances'.
Post by: Lighties on June 10, 2010, 11:02:33 pm
The answer is definitely 2. The exact wording reads:
"What is the number of equivalent protons bonded to the adjacent carbon atom?"
"equivalent proton" here refers to protons that are the same environment compared to each other. It is well established that the adjacent carbon atom is bonded to two H, and these two H are in the same, thus there are two equivalent protons bonded to the adjacent carbon.
If you have interpreted it the other way, the question would have read:
"What is the number of protons bonded to the adjacent carbon atom that are equivalent to the protons detected atppm?"
This question doesn't make logical sense. If the answer is more than 0, i.e. the carbon and H environments are equivalent, all of these protons will be found in the same peak at 1.3ppm, thus it will be referring to the adjacent carbon atom that is of a different environment. Hence the answer has to be 0, and the interpretation goes 'how many other protons outside of this peak is equivalent to this peak? 0 under all circumstances'.
That's some pretty good logic, but isn't 0 technically a correct answer? And why did they even include the word 'equivalent'?
Post by: crayolé on June 10, 2010, 11:04:18 pm
It's just sucky english that goes both ways
Post by: Mao on June 10, 2010, 11:07:02 pm
So as opposed to saying "it has a neighbouring -CH2- group", you can say "there are two neighbouring equivalent protons".
Post by: Lighties on June 10, 2010, 11:11:55 pm
Sigh, my explanation is completely wrong, there goes another mark. >.>
Urgh at sucky english/not enough knowledge for chem.
Post by: Davoo! on June 10, 2010, 11:17:43 pm
if this is another ghey friggin vcaa trick ill be pisseeeddd
fuckn hell. dont know whether everyone's overthinking it or what. but this exam has just turned out to be the biggest bitch. I studied so much for it and if it ends up ive lost majority of my marks on stupid crap like this it'll piss me off. What'll piss me even more off is if i end up doing better for physics (which it looks like might be the case) when i did not study for physics and a absolute shitload for chem.
rawwwwwrrrrrrrrrrr
I feel your pain.
Physics 6 exams, and I feel really confident.
Chemistry 17 exams, and I'm so sure I got analed by their 4375643979836753 booby traps.
Post by: clumsy_culhane on June 12, 2010, 08:31:23 pm
The answer is definitely 2. The exact wording reads:
"What is the number of equivalent protons bonded to the adjacent carbon atom?"
"equivalent proton" here refers to protons that are the same environment compared to each other. It is well established that the adjacent carbon atom is bonded to two H, and these two H are in the same, thus there are two equivalent protons bonded to the adjacent carbon.
Thanks for the clear-up Mao. I put down 0 as well, as I thought as per a few practice exams, that splits have to be formed from non-equivalent protons. Maybe they will give marks for both 0 and 2, as it's somewhat ambiguous? Far out.. this makes me annoyed, they put that equivalent word in there, and a lot of the people that really thought about the question then got it wrong :(
Edit: From KBT solutions :"If the hydrogens of a particular environment have n neighbouring, non-equivalent hydrogens,
the peak from that environment will be split into n+1 component peaks.
Keep in mind that the word ‘neighbouring’ as it’s used above means ‘on the adjacent carbon
atom’. ‘Non-equivalent’ means ‘not of the same environment’."
And yes, I know I'm now wrong as proven by Mao in all his awesomeness, but I still want to feel a little right...
(http://www.kbtlectures.com/wp-content/uploads/2010/04/KBT_unit3chemistry_trialexamsolutions.pdf)
Post by: sajib_mostofa on June 30, 2010, 02:44:46 pm
Post by: kenhung123 on June 30, 2010, 02:58:11 pm
Post by: sajib_mostofa on June 30, 2010, 03:29:26 pm
Post by: pooshwaltzer on June 30, 2010, 07:23:22 pm
It most likely you are not used to the chemistry wording of it. Its saying how many hydrogens in the same chemical environment adjacent to the hydrogen under investigation causes a triplet in NMR spectrum
Guys,
Even though the answer is 2, it would be probable to attract consequential/consolation marks IF adequate explanation was provided to substantiate the albeit flawed construction of the facts surrounding the question. So if your explanatory paragraph provides logical and rational justification of the answer 0, despite it being a misinterpretation of the question, then SOME marks will be awarded for commensurate effort with due regard and consideration.
Post by: kenhung123 on June 30, 2010, 10:26:18 pm
Post by: m@tty on June 30, 2010, 11:58:08 pm
And honestly I think that 0 has no chance of getting the mark; even though on reading it is ambiguous, that wording is prevalent when dealing with these type of questions.
Post by: iffets12345 on July 01, 2010, 12:12:38 am
Is the debate as to what equivalent proton means?
e.g:
Side A believes equivalent proton means protons similar to the Ch3 environment.
Side B states equivalent protons are just Hs on the adjacent carbon which are esentially in the same environment.
I HOPE I WROTE TWO FREAKING HELL.
Post by: chansthename on July 01, 2010, 12:01:40 pm