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View Full Version : Alkanes, Isomers and Formulas; I don't understand Chemistry



Bastinka
September 7th, 2009, 12:23 PM
Title says it all, I've never had any experience in Chemistry although I got put in a class that I have to be in (forced), Germany, and yet I have no idea what it's asking me to do.

Here's a picture of the sheet (English side):
http://img186.imageshack.us/img186/3948/alkanes.jpg


Please help me modacity :(
I have such a hard time understanding it, and google didn't solve anything.

Cojafoji
September 7th, 2009, 12:36 PM
http://www.google.com/search?hl=en&source=hp&q=define%3Aalkanes&aq=f&oq=&aqi=
http://www.google.com/search?hl=en&safe=off&q=define%3AIsomers&btnG=Search

Bastinka
September 7th, 2009, 12:45 PM
Would it have 2 different isomers or more?

Peterljr888
September 7th, 2009, 12:58 PM
I took Chem last year but I don't have a lot of experience with this specific topic so bear with me.
http://en.wikipedia.org/wiki/Alkane
http://en.wikipedia.org/wiki/Structural_isomerism

Spoiler below for #1, #3
http://en.wikipedia.org/wiki/Pentane
http://en.wikipedia.org/wiki/Isopentane
http://en.wikipedia.org/wiki/Neopentane


#2: condensed formula definition (http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-C/condensed_formula.html)

All 7 of the structures have the same chemical formula (C5H12), but some of them are structurally different than others. (definition of an isomer)

Rentafence
September 7th, 2009, 01:12 PM
Cool, I love Chemistry. Too bad my experience with it is limited to a single course in 11th grade. That'll change come college though where I plan on majoring in it.

I'm definitely no expert on this seeing as I haven't even done this type of stuff before, but I think I have somewhat of an idea of how this works after 5 minutes of reading it up on google. Take it with a grain of salt though.

Anyway, C5H12 is pentane.
http://www.gcsescience.com/n-pentane.gif



Ok, so, to find the isomers, imagine taking one of the end CH2 groups and attaching it on the end of another CH2 group.

You have
http://www.creative-chemistry.org.uk/molecules/images/dispmethylbutane.gif

This I would be called 2-methyl butane, because you took a CH2 group and stuck it on the end of the second CH2 group. Butane I'm assuming since it has 4 carbon atoms in a chain now. If you threw around that same CH2 on different sides/ends, you would still have the same molecule, just form a different perspective.

Now, take the other CH2 group and stick it on the other end, so you would get neopentane, or 2,2 dimethyl butane, because of the 2 methyl groups on the ends.

http://upload.wikimedia.org/wikipedia/commons/3/37/Neopentane.PNG



In all, the first one would have 3 isomers, pentane, 2-methyl butane, and 2,2-dimethyl butane. I guess if you just apply that idea to the other formulas you can figure out the names.

E-Sorry for the quad post, I must have hit post instead of edit or something.

Bastinka
September 7th, 2009, 01:18 PM
I understand it now, but I talked to a friend and he said in Chemistry you get a book that shows the names of the formulas (Methylbutane, Ethylpropane, etc.) stuff like that. Yet I never got a book, instead homework with no explanation on how to do it so I freaked.

Thanks!

ddddyyyy
September 7th, 2009, 07:45 PM
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ultama121
September 7th, 2009, 07:47 PM
At least it doesn't attempt to conceal the fact its a bot.

Sel
September 7th, 2009, 07:47 PM
lol..

Timo
September 7th, 2009, 08:58 PM
First 3 and 5 are Pentane, 4 is 2-methyl butane, as is 6. I think 7 is 2 dimethyl propane. Been a while since i've seen organic chem :x