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What is the structural formula of C5H8?I know that cyclopentene can be a structure of...

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claymore | Student, Undergraduate | eNoter

Posted January 3, 2013 at 10:26 PM via web

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What is the structural formula of C5H8?

I know that cyclopentene can be a structure of C5H8, but I don't know the correct way to draw it.

Are there double bonds? Is there an easier way of drawing it?

I need to show the Cs and Hs and bonds.

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ncchemist | eNotes Employee

Posted January 4, 2013 at 2:49 AM (Answer #1)

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There are three possibilities for the structure of C5H8.  Regular pentane is ruled out since it would be C5H12.  Regular pentene (with one double bond) is ruled out since it would be C5H10.  The ppossibilities are cyclopentene (as you mentioned), pentyne, and pentadiene.

Cyclopentene is a cyclic compound with one carbon carbon double bond.  I can't really draw it out here but draw the shape of a basic pentagon with a carbon in each corner.  One of the sides will have a double bond (two lines).  The carbons involved in the double bond will only have one hydrogen each.  The other three carbons will each have 2 hydrogens (for a total of 8 H's).

Pentyne has one carbon carbon triple bond.  It can be represented as HC`-=`C-CH2-CH2-CH3.  The first carbon bond here is the triple bond.

Pentadiene is a linear compound with two separate double bonds.  It can be represented as H2C=CH-CH=CH-CH3. 

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