Thursday, 1 March 2007

SAT Question of the Day

How many isomers could hypothetically exist with the molecular formula C3H5Cl?

(A) 1
(B) 3
(C) 4
(D) 5
(E) 6

22 comments:

Anonymous said...

5 ?

Chemist said...

I found 4:( Is that corect. blog owner are you a teacher or sth like that???
Nice demonstration at the last Ace Chemistry SAT II

Chemist said...

is that corect?*

Blog owner said...

I will give the right answer tomorrow.
I am actually a student in the university (chemistry, of course) but during the high school I participated 3 times in International Olympiads (I have been awarded the gold medal only once, though). Actually when I took the SAT at chemistry i did not prepare at all - but I "aced" it - and I became involved in this blog only when some of the students to whom I have been TA started to ask me questions about chemistry and about SAT.

Chemist said...

are u from USA?
at what university do u study??? I am from Romania and I have almost 3 years until i have to choose a university but i ont know what to do...to go outside or to stay here. i participate at national olympic at chemistry this year..and i participated ;last year too:)

Blog owner said...

There are 5 isomers:
Just make sure to include cis and trans isomers as two different ones, and to draw also the cyclopropane ring with a chlorine attached and that's it.

Chemist said...

I forgot the cyclopropane ring:(

obesechicken13 said...

I see one, since the carbons have to be in the center H and Cl only need one more electron to be complete. that means everything is single bonded with a carbon in the middle right? no wait carbon has 4 valence arggh, im new to this,,,:( 2 double bonds so no triple or recursion, draw a picture and post it anyone?

Anonymous said...

yay it got it rite ! hehe

Blog owner said...

So, this are the structures of the isomers:
cis CH3-CH=CHCl
trans CH3-CH=CHCl
CH3-CCl=CH2
CH2Cl-CH=CH2
Chlorocyclopropane - a cyclopropane with a chlorine attached.

Anonymous said...

woah i kinda did it differently (didnt use cis and trans and the cyclopropane, but just wrote out the structural formula) but got the same answer .. wats the cyclopropane ?

Chemist said...

cyclopropane is a cycle of 3 atoms of C


like this CH2
/ \
CH2-CH2

its not that stable because of the tension in the cicle. and Chlorocyclopropane uis like this
Cl
|
CH
/ \
CH2-CH2

IIts the best i could do to draw you the structure

Chemist said...

http://en.wikipedia.org/wiki/Cyclopropane

you can read here about it
its a little complicated here but you can try to understand:)

Anonymous said...

ohh okay

Anonymous said...

There are E and Z isomers, but not cis and trans because the groups are different.

Anonymous said...

WTF are cis and trans and E and Z?

I'm gonna spam my chemistry teacher's e-mail cause he never taught us SHIT! all he did was talk about catching moles in his backyard, what a nub!

Anonymous said...

how can you distinguish between the 5 isomers of c3h5cl? I found this question in a book and can't answer it :/ i'll appreciate any help

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