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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Problem of the Week Archive => Topic started by: Borek on September 17, 2012, 12:56:12 PM

Title: Problem of the week - 17/09/2012
Post by: Borek on September 17, 2012, 12:56:12 PM
An olefin reacting with Br2 yields a substance containing 69.50% bromine and a single chiral carbon. Name the olefin.
Title: Re: Problem of the week - 17/09/2012
Post by: fledarmus on September 17, 2012, 01:42:19 PM
I'll try this one! How about "George"? Or maybe "Bob"? Or "Sue"...

Title: Re: Problem of the week - 17/09/2012
Post by: discodermolide on September 17, 2012, 01:46:05 PM
I think I know the answer, but will not spoil it for others.
But following Fledarmus's lead I will call it Fred as in Flintstone.
Title: Re: Problem of the week - 17/09/2012
Post by: Borek on September 17, 2012, 01:54:11 PM
Nice try, but I was thinking about more systematic approach  :P
Title: Re: Problem of the week - 17/09/2012
Post by: discodermolide on September 17, 2012, 03:08:38 PM
Well I used my drawing tools, which give elemental analysis. Going through the parameters you give it spat out Fred Flintstone.
I stlll don't want to spoil it for others. You must insist that I provide an answer. But let's wait a bit >:D
Title: Re: Problem of the week - 17/09/2012
Post by: CrazyAssasin on September 17, 2012, 03:26:00 PM
I'm not certain about the answer, but I think it's should be 2-metil-1-butene
Title: Re: Problem of the week - 17/09/2012
Post by: Rutherford on September 18, 2012, 10:21:14 AM
I don't understand how only one olefin could be the answer. I got two actually.
Title: Re: Problem of the week - 17/09/2012
Post by: CrazyAssasin on September 18, 2012, 10:38:36 AM
Could you name them, because I can find only one.
Title: Re: Problem of the week - 17/09/2012
Post by: Rutherford on September 18, 2012, 11:13:25 AM
Yours, and 1-pentene, which has a chiral C atom too (H, Br, CH2Br and C3H7 are bonded to him).
Title: Re: Problem of the week - 17/09/2012
Post by: CrazyAssasin on September 18, 2012, 11:27:01 AM
Yes you're right, I didn't think about this one.
Title: Re: Problem of the week - 17/09/2012
Post by: fledarmus on September 18, 2012, 01:22:10 PM
What about 2-methyl-2-butene?
Title: Re: Problem of the week - 17/09/2012
Post by: Rutherford on September 18, 2012, 01:42:24 PM
Yes, that one has a chiral C, too.
Title: Re: Problem of the week - 17/09/2012
Post by: Schrödinger on September 18, 2012, 01:56:47 PM
Yeah, so don't we have 3 possibilities? Just consolidating : pent-2-ene, 2-methylbut-1-ene and 2-methylbut-2-ene.
Title: Re: Problem of the week - 17/09/2012
Post by: Borek on September 18, 2012, 02:07:22 PM
You should already know if the question I posted contains word "chirality", something must be wrong  >:D

More seriously, question was intentionally lousy. To be honest I didn't even know how lousy it is - that is, I knew of two possible reasons why the answer is not unique (BTW: one was not yet mentioned in the thread, although I was contacted by PM by fledarmus), could be there are even more problems with the question. But I wanted to stir a discussion and I know from experience best way to catch your attention is to post some kind of nonsense  :P

I wanted to ask you about Problem of the Week - do you think it makes sense to continue (I do plan to), do you have any ideas about how to make it more interesting, do you know questions that you think will fit, or perhaps you just have an idea that you think could be made into an interesting question with some work?
Title: Re: Problem of the week - 17/09/2012
Post by: Rutherford on September 18, 2012, 03:43:45 PM
" do you think it makes sense to continue"
Continue please, there were many interesting problems.
These are my favorites till now:
http://www.chemicalforums.com/index.php?topic=59349.0 interesting because of the story
http://www.chemicalforums.com/index.php?topic=57924.0 interesting because of using more maths (quadratic inequality)
http://www.chemicalforums.com/index.php?topic=58982.0 one really really nice problem. Would like to see similar.
I didn't like some of the inorganic guessing tasks (this is only my modest opinion of course), and I would like to see organic more (would be nice to have some problem of the week in the organic section that is for students-not professionals. I started to learn it 3 months ago and I found it very interesting, but never mind).
Title: Re: Problem of the week - 17/09/2012
Post by: DrCMS on September 19, 2012, 04:45:20 AM
I agree with Raderford carry on doing them please Borek.  I especially liked the middle one Raderfordd linked to as that involved a bit to completely solve it and is a more real world application of chemistry.  I'd like to see more questions like that that require a bit of thinking about and working out rather than just a google search to find a compound with the right mass/colour/other property etc.  but I enjoy trying to get the right answer to all these questions.
Title: Re: Problem of the week - 17/09/2012
Post by: Schrödinger on September 19, 2012, 05:38:55 AM
Please do continue. I haven't active in this POTW section, but that's only because I lack chemical knowledge. I am still in the learning phase, getting to know stuff. For instance, I know nothing of several topics like electrochem, thermodynamics, acid-base titration, etc. It will take me atleast a year to master these concepts properly (atleast the basics). But reading this section and going through discussions has always been a pleasure
Title: Re: Problem of the week - 17/09/2012
Post by: AWK on September 19, 2012, 06:31:34 AM
Yeah, so don't we have 3 possibilities? Just consolidating : pent-2-ene, 2-methylbut-1-ene and 2-methylbut-2-ene.
Theoretically one more example is possible - bromination of CH2TF (T - tritium)
Title: Re: Problem of the week - 17/09/2012
Post by: Borek on September 19, 2012, 07:30:50 AM
CH2TF (T - tritium)

That's not an olefin - olefin must be unsaturated.
Title: Re: Problem of the week - 17/09/2012
Post by: fledarmus on September 19, 2012, 08:42:49 AM
Yes, please continue the problems of the week! I rarely contribute an answer, but I enjoy the process of thinking through the problems and reading what other people come up with. The more-or-less real world applications are my favorites.
Title: Re: Problem of the week - 17/09/2012
Post by: Borek on September 24, 2012, 08:07:14 AM
I am going to try a problem with a chiral compound once again  :P

As mentioned earlier, there are more possible answers. Generally speaking there are probably infinitely many answers, as every compound with the formula (C5H10Br2)n will have the same bromine percentage.