# chem-repost

posted by on .

I ddin't know if anybody would look far down to page to help me answer my question but this is what was said so far.

Posted by rebekah on Sunday, October 24, 2010 at 4:48pm.

Give the general formula for any dialkene; that is, a straight-chain hydrocarbon with two double bonds along the chain. (Type your answer using the format CnHn+1 for CnHn+1.)

I know just alkene would be CnH2n but im not sure how to make it with the dialkene.

can any1 help me?
thanks!!

chem - bobpursley, Sunday, October 24, 2010 at 4:58pm
draw some

cH3-cH2-cH=cH-cH=cH2

note on the ends, there are 3H
one each double bond, each C has one less H (each side)

CnH(2+2n-4) check that above n=6, byt this formula C6H10 counting... 6c, 10H

now the check
CH2=CH-CH2-CH=CH2
formula: C5H8
count: C5H8

CnH(2n-2) Try that.

chem - rebekah, Sunday, October 24, 2010 at 5:02pm
oh. that wasn't the correct answer

chem - DrBob222, Sunday, October 24, 2010 at 5:42pm
Try some. The general formula for a dialkene is the same as the general formula for an alkyne isn't it. CnH2n-2.
I wrote about six or 7 straight chain hydrocarbons, stuck a couple double bonds in each, added H atoms to make up the quadrivalent C each, and voila! All of them worked with CnH2n-2.

chem - rebekah, Sunday, October 24, 2010 at 5:46pm
i tried the answer in my online hw and it said it was wrong. i am looking in my text book and CnH2n-2. the answer you guys are saying is the formula for alkynes.

but i need to find the formula for dialkene.

the formula for just alkene is CnH2n. but i don't know how to make that into the di part of dialkene

• chem-repost - ,

WEll, both of us showed you, I am sorry it is marked wrong.

• chem-repost - ,

but. i can tell its wrong because of what i stated:

"i tried the answer in my online hw and it said it was wrong. i am looking in my text book and CnH2n-2. the answer you guys are saying is the formula for alkynes.

but i need to find the formula for dialkene.

the formula for just alkene is CnH2n. but i don't know how to make that into the di part of dialkene"

is there anyone else that knows the answer?