[patrisha_boo]

1)
   h h h h h h h h
h-c-c-c-c-c-c-c-c-h
   h h h h h h h h

2)
   h h h h h h   h    h
h-c-c-c-c-c-c -  c-    c-h
  h h h h h h   h  h-c-h
                           h
3)
   h h h h h h
h-c-c-c-c-c-c-h
   h h h h hch-hch
                h    h
4)
   h h h h h  
h-c-c-c-c-c-h
   h h hch hch-hch
          h    h    h
5)
   h    h    h    h
h-c-   c-   c-    c  -h
  hch hch hch hch
    h    h    h    h

I don't really know how to find the other 13 isomers.

[AWK]

It should be 18. Try to name all these isomers.

[Octane]

n-octane

2-methylheptane
 3-methylheptane
4-methylheptane

2,2-dimethylhexane
2,3-dimethylhexane
2,4-dimethylhexane
2,5-dimethylhexane
3,3-dimethylhexane
3,4-dimethylhexane
3-ethylhexane

2,2,3-trimethylpentane
2,2,4-trimethylpentane
2,3,3-trimethylpentane
2,3,4-trimethylpentane
3-ethyl-2-methylpentane
3-ehtyl-3-methylpentane
 
2,2,3,3-tetramethylbutane

I belive that that is all, I have rechecked them several times and no doubling, there is 18 of them too.

[Donaldson Tan]

gosh.. 900++ views for this post.. LOL

[Communique]

2,3,4-trimethylpentane
3-ethyl-2-methylpentane
3-ehtyl-3-methylpentane

Wouldnt it be
3,3,4-trimethylpentane
2-methyl-3-ethylpentane
3-methyl-3-ethylpentane

The last two I think are the same as what you have posted, just named a little differently. As a lab in chem class were supposed to name and draw out all the isomers of octane and my question is, would a difference in naming like that matter at all? Because they are really the same thing I think...

[janne18]

Wouldnt it be
3,3,4-trimethylpentane
2-methyl-3-ethylpentane
3-methyl-3-ethylpentane

The last two I think are the same as what you have posted, just named a little differently. As a lab in chem class were supposed to name and draw out all the isomers of octane and my question is, would a difference in naming like that matter at all? Because they are really the same thing I think...

Nope. I agree with Octane. Remember that substituents are supposed to have the lowest possible numbers and that the substituents should be in alfabetic order. ethyl before methyl

[AWK]

Octane did some errors.
the proper name of all isomers are (left to right, up to down  - see my scheme):
n-octane,  2-methylheptane, 3-..., 4-...,
2,2-dimethylhexane, 2,3-..., 2,4-..., 2,5-...,
3,3-dimethylhexane, 3,4-..., 3-ethylhexane,
2,2,3-trimethylpentane, 2,2,4-..., 2,3,3-..., 2,3,4-...,  3-ethyl-2-methylpentane,
3-ethyl-3-methylpentane,
2,2,3,3,-tetramethylbutane.

[woelen]

It should be 18. Try to name all these isomers.

Wow... you did your homework very well.

Just to tease you with this puzzle on alkanes....
What is the generic mathematical expression of the number of isomers of C_nH_2n+2?
Give the number of isomers as an integer function of n.

Below follows the value of this function for some small values of n.

1 1
2 1
3 1
4 2
5 3
6 5
7 9
8 18
9 35
10 75
12 355
15 4347



Wilco

[AWK]

http://www.scctm.org/Awards/Ballard_Paper.pdf