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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: puremercury on May 15, 2006, 08:29:46 PM

Title: isomer
Post by: puremercury on May 15, 2006, 08:29:46 PM
How can there be 3 isomer for C3H4? isn't it a alkyne? i can only figure out one structural formula with triple bond
Title: Re: isomer
Post by: mike on May 15, 2006, 08:39:22 PM
H2C=C=CH2 maybe? :-\
Title: Re: isomer
Post by: rctrackstar2007 on May 15, 2006, 08:40:08 PM
How can there be 3 isomer for C3H4? isn't it a alkyne? i can only figure out one structural formula with triple bond

if you move the triple bond to the other side that is an isomer, but i don't know where a third would come from
Title: Re: isomer
Post by: rctrackstar2007 on May 15, 2006, 08:41:18 PM
H2C=C=CH2 maybe? :-\

that's good, that would make all three...
Title: Re: isomer
Post by: mrdeadman on May 15, 2006, 08:42:27 PM
if you move the triple bond to the other side that is an isomer, but i don't know where a third would come from
you can't really do that though, because it would still be 1-propyne, or whatever, you number it from the lowest number.
Title: Re: isomer
Post by: mike on May 15, 2006, 08:43:18 PM
Oh, cyclopropene of course!
Title: Re: isomer
Post by: mrdeadman on May 15, 2006, 08:43:37 PM
H2C=C=CH2 maybe? :-\
this one makes sense to me but i have no clue where the other one comes from.
Title: Re: isomer
Post by: mrdeadman on May 15, 2006, 08:44:44 PM
Oh, cyclopropene of course!
dang, didn't even think about the cyclos, nice mike.  :)
Title: Re: isomer
Post by: puremercury on May 15, 2006, 08:54:47 PM
humm. that's weird. i was just reviewing organic chem from last year. and i thought an alkyne must have a triple bond. and apparently H2C=C=CH2 content 2 double bond. how does this work. isn't that a Alkene but C3H4 don't have the general formula of CNH2N. how could this be an alkene?
Title: Re: isomer
Post by: mrdeadman on May 15, 2006, 09:02:36 PM
the molecular formula won't tell you whether or not it is an -ane, -ene, or -yne at times, like this one, you can't really infer that it is an alkyne based solely on the chemical formula, this isn't general chem anymore.
Title: Re: isomer
Post by: rctrackstar2007 on May 15, 2006, 09:09:09 PM
the molecular formula won't tell you whether or not it is an -ane, -ene, or -yne at times, like this one, you can't really infer that it is an alkyne based solely on the chemical formula, this isn't general chem anymore.

ya you can if that is the entire formula unless a molecular charge hasn't been stated
Title: Re: isomer
Post by: syko sykes on May 15, 2006, 09:13:32 PM
the molecular formula won't tell you whether or not it is an -ane, -ene, or -yne at times, like this one, you can't really infer that it is an alkyne based solely on the chemical formula, this isn't general chem anymore.

ya you can if that is the entire formula unless a molecular charge hasn't been stated
no... the molecular formula doesn't give you structure and you can't determine -ane, -ene, or -yne without the structure or the molecule as shown by the multiple isomers in previous posts
Title: Re: isomer
Post by: puremercury on May 15, 2006, 09:15:23 PM
umm. i have no idea what the last 2 post mean. sorry :-X
Title: Re: isomer
Post by: syko sykes on May 15, 2006, 09:19:02 PM
umm. i have no idea what the last 2 post mean. sorry :-X
then ignore those 2 posts and just remember what mrdeadman said: molecular formula doesn't always distinguish between -ane, -ene, and -yne
Title: Re: isomer
Post by: puremercury on May 15, 2006, 09:50:15 PM
but isn't there way of telling whether the molecular formula is only infering to one of the three group or all in general ?
Title: Re: isomer
Post by: mrdeadman on May 15, 2006, 09:56:34 PM
not really unless it specifies, like: 2,3-dimethylpentane. i have never seen a problem where they ask you to name a organic molecule based on the molecular formula.
Title: Re: isomer
Post by: mike on May 15, 2006, 10:11:52 PM
Quote
but isn't there way of telling whether the molecular formula is only infering to one of the three group or all in general ?

Nope. Plus you asked for the isomers.

http://www.chemicalforums.com/index.php?topic=1835.msg39521#msg39521
Title: Re: isomer
Post by: puremercury on May 15, 2006, 11:16:43 PM
Thanks alot guys. i think i understand better now.