Drawing H-Bonded Structures: Dimers and Cyclics

[MysticDude]

Homework Statement

Draw each of the following H-bonded structure (a) (HF)₂ dimer; (b) (CH₃OH)₄ cyclic.

Homework Equations

The Attempt at a Solution

I truly don't know where to begin. I started by searching about dimers and found a http://en.wikipedia.org/wiki/Dimer_%28chemistry%29" but that confused me even more. Are the drawings supposed to be like the crystal structure of H₂O?

Thanks for any help.

 

[chemisttree]

Well, H likes F so for (HF)₂ put two H's around an F and put the other F in a position to bond to the same two H's in an identical fashion. Same thing goes for methanol but replace F with O... and stick a methyl group on the O's so that it doesn't interfere with the groovy coolness of the hydrogen bonding.

 

[MysticDude]

Wait so with (HF)₂, would it be something like H--F~H--F? This is like [H--O--H]~[H--O--H].

 

[chemisttree]

No. Both F's must bond with both H's. It's not linear. Go in a more groovy direction...

 

[MysticDude]

So something like this(I hope the format stays):
H~~F
|...|
F~~H

This was the best way I could think of both Fs bonding with both Hs

Ignore the dots

 

[chemisttree]

Ohhhh! You found the groovy coolness! Nirvana!

 

[MysticDude]

AWESOME! Now onto (CH₃OH)₄ cyclic. This one will be hard to draw using the forum so I'll have to go to pictures, but I can use your help. I know how to draw the Lewis Structure, but I have no clue what cyclic is.

...H
...|
H--C--O--H
...|
...H

 

[chemisttree]

Just replace the F's with O's and add a methyl group to each O... dude!

 

[MysticDude]

Oh ok that's easy. But what is a cyclic though? I want to understand that! Oh and I am in no way trying to draw the Lewis Structure on the forum here lol. I mean I can but that would be annoying!
:D

 

[chemisttree]

Once you make the dimer of methanol, you will notice that the H-O-H-O square is a cyclic containing only two methanol groups. Can you draw one that has 4?

 

[MysticDude]

I'm thinking about it.
Would it be something like this?:
H~~O--H
|...~
|...O
|...|
|...H
|...~
O~~H--O

I understand that the diagram can be confusing, but I hope someone like you could understand me! Every O is connected to 2 H. I think that this would be correct.

:D

 

[Borek]

And you think right.

 

[chemisttree]

That's good enough for the forum but you need to add the methyl groups to the O's for the assignment that you turn in.

What do you think about the entropy of cyclics going from dimers to trimers to quadramers, etc...?

 

[MysticDude]

That's good enough for the forum but you need to add the methyl groups to the O's for the assignment that you turn in.

What do you think about the entropy of cyclics going from dimers to trimers to quadramers, etc...?

Okay yeah I did that stuff for the problem. But your question is too complex as we have not studied that area in chemistry. I know what entropy is but your question is something that I have studied. But I thank you sooo much for helping me!

:D