Help understanding a lab - intermolecular bonding

  • Thread starter Jchem
  • Start date
28
0
Hello, I have done an experiment and I am having trouble explaining why certain things happen.

The topic is intermolecular bonding. I used three liquids, each is composed of different types of bonds.

liquid 1) Hydrogen bond
liquid 2) bonding due to dipole forces
liguid 3) bonding due to Van der Waals forces

Basically I take a liquid, put it in a cup and stir it really fast. I record the depth of the maximum vortex and the amount of time that it lasts.

Then do the same with the other two liquid. (same amount, same container).


---------------------------------------------------------------------

Now, I have 3 different values for the amount of time the vortex lasts, and I'm trying to understand why (in terms of intermolecular bonding). The answer that comes to mind is viscosity, but it is nowhere in the course.. so I dont think thats what I'm supposed to be looking for.

My second question is why is water (hydrogen bonding) so much different than the other two in terms of the depth of the vortex?

I know that hydrogen bonding is the strongest, but I'm not sure how that piece of information applies to the vortex.. as no bonds are being broken.



thanks for any help
 
1,100
0
Am I to assume that the liquid that hydrogen bonds has a deepest vortex???

The Bob (2004 ©)
 
28
0
EDIT: Ok something is wrong here.. so I'm doing the experiment again.

I'll post the results as soon as I'm done
 
Last edited:
1,100
0
Jchem said:
thanks for the quick response :smile:


.......................Depth of vortex..............Time votex lasted

Vander waal ........... 2.5 cm.............................9s..............
dipole......................(.5 cm)............................1s...............
Hydrogen Bond:...........2.2...............................12s............


and I'm not sure about my results (although I've done them several times) because question 2 asks why the water (hydrogen bond) is so different in terms of depth of vortex and time.... but it isn so different.. its just slightly different.
Are you sure about these results? I only ask because I would expect the hydrogen bonding to cause the biggest vortex and but also to be the first to stop, which goes against what you have said.

The explaination is that the strong forces would cause the molecules to get pulled to one side more (so big vortex) but also because of the forces it would slow down fastest because the pull would do that. However it could be that the attractive forces cause the molecule to pull against each other and this would suggest a smaller vortex and a longer time to settle because the molecules are being pulled by each other more than in van der Waal's.

The Bob (2004 ©)

P.S.
Jchem said:
dipole.........(.5 cm)
Is that 0.5cm or what???
 
28
0
yes that is 0.5 cm
 
1,100
0
Jchem said:
yes that is 0.5 cm
It is intersting. I would say that the dipole is the intermediate force and so is not at one end of the spectrum. This means will give the result it does. The other two are at opposite ends and so act in similar ways (e.g. hydrogen bonds are strong so attract more than van der Waal's but moving act in similar ways).

The idea is in my head but I do not have the time (my dad's faylt) to write it down. Also some other people might give me some inspiration.

The Bob (2004 ©)

P.S. Time for bed :smile:
 

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads

Top