SRL Archive - Science

I've tried so hard to understand this, and I will eventually figure it out, but I have yet to "click" in my mind on how to do this.

Part A:

Draw the Lewis structure of Methanoic Acid (HCOOH):

I think I have this one. Paint skillz:

Is that right? I don't see how else to do it while using hybridization. I could have a coordinate covalent bond maybe, but I don't know if that would work anyway.

Part B:

In methanoic acid, predict the bond angle around

i) the carbon atom
ii) the oxygen atom bonded to the hydrogen atom

I have no idea how to do this.

Part C:

State and explain the relationship between the length and strength of the bonds between the carbon atom and the two oxygen atoms in methanoic acid.

I think that polarity will affect (effect?) the bond length, and hence the strength of the bonds, but I don't really know how to go about explaining it well enough for 4 points, which usually involves 3 or 4 things being mentioned.

If you can lead me in the right direction, teach me, tell me the answer, whatever you must do, to help me get this finished by tomorrow, I would love you forever. Homo, or no homo, depending on your preference.

ew lewis. Bohr ftw.

yes your part a is right.

and i have no idea for part b, sorry :o

From: bionicle1800
ew lewis. Bohr ftw.

yes your part a is right.

and i have no idea for part b, sorry :o

Bohr, the circle ones? They don't even properly explain it. I think they teach it in university normally, but being in super advanced chemistry, I learn it in grade 12.

From: 3Garrett3
Bohr, the circle ones? They don't even properly explain it. I think they teach it in university normally, but being in super advanced chemistry, I learn it in grade 12.

your right, but theyre simpler and easyer to understand imo

From: bionicle1800
your right, but theyre simpler and easyer to understand imo

I don't know if they're as good for hybridization. Do you know how to do part C?

From: 3Garrett3
I don't know if they're as good for hybridization. Do you know how to do part C?

well i fail at chemistry…so i have no idea. something with ions? idk

Okay. Well for part A, zeph told me it was wrong, so I wiki-d it.

I found this:

http://en.wikipedia.org/wiki/Formic_acid

So it looks different than I thought. The shape looks to be Trigonal Planar, which has bond angles of 120 degrees. I don't really understand the second part of b, or part C yet, but I'm working on it.

Part B
ii)
It would be

Part C

State and explain the relationship between the length and strength of the bonds between the carbon atom and the two oxygen atoms in methanoic acid.



The as the length of the bond increase, the London disperson force will decrease because the positive nucleus is farther apart from the electrons.

[irrelevant explanations below]
Since this molecule is polar covalent, the electrons (from the carbon) will more likely to appear around the oxygen than the carbon.

From: Main_Ftw
Part B
ii)
It would be

Part C

State and explain the relationship between the length and strength of the bonds between the carbon atom and the two oxygen atoms in methanoic acid.



The as the length of the bond increase, the London disperson force will decrease because the positive nucleus is farther apart from the electrons.

[irrelevant explanations below]
Since this molecule is polar covalent, the electrons (from the carbon) will more likely to appear around the oxygen than the carbon.

For Part B: What is the answer to part II. I don't even understand what it wants.

Part C: Would it be correct to state "The double bonded carbon-oxygen bond is shorter and stronger than the single bonded carbon-oxygen bond. This is because the attraction between the electrons in a double bond is stronger than in a single bond, which pulls the atoms closer, while strengthening the bond"

??

E: Ps- MSN? maniac234 AT hotmail.com

I thought it was asking what happens to the strength if we change the length.


O yes, Dipole bonds are a bit stronger. I've been doing too much organic stuff where we only care about the intermolecular forces.

Every atom needs to fill its' shell of electrons.

The first shell has 2 electrons. The second has 8.

In your first drawing, the Carbon only has 6 electrons associated with it, when it needs 8. It gets 8 by participating in 4 covalent bonds… 1 with hydrogen, 2 with the first oxygen, and one with the second oxygen.

For the bond angles, you only have 3 options. Linear, trigonal planar, or tetrahedral. The carbon only interacts with 3 other atoms, so you know it's going to be a trigonal planar interaction, with each bond angle being 120 degrees. If it associated with only 2 other atoms (like in your incorrect attempt at drawing the molecule) it would be linear, with a bond angle of 180. If it interacts with 4 other atoms, it would be tetrahedral with an angle of 108 or whatever it is. I don't remember now.

As for the length of the bond, a double bond will always be shorter and stronger than a single bond. So one bond will be shorter and stronger and the other will be longer and weaker.

The polarity does come into play a bit, but it seems beyond the scope of the question. Carbonyl (C double bond O) bonds will draw electrons toward them. This will pull electrons toward the C and away from the O-H. That polarity makes the O-H bond weaker, and leads to loss of the H as an acidic proton.

From: tarajunky
Every atom needs to fill its' shell of electrons.

The first shell has 2 electrons. The second has 8.

In your first drawing, the Carbon only has 6 electrons associated with it, when it needs 8. It gets 8 by participating in 4 covalent bonds… 1 with hydrogen, 2 with the first oxygen, and one with the second oxygen.

For the bond angles, you only have 3 options. Linear, trigonal planar, or tetrahedral. The carbon only interacts with 3 other atoms, so you know it's going to be a trigonal planar interaction, with each bond angle being 120 degrees. If it associated with only 2 other atoms (like in your incorrect attempt at drawing the molecule) it would be linear, with a bond angle of 180. If it interacts with 4 other atoms, it would be tetrahedral with an angle of 108 or whatever it is. I don't remember now.

As for the length of the bond, a double bond will always be shorter and stronger than a single bond. So one bond will be shorter and stronger and the other will be longer and weaker.

The polarity does come into play a bit, but it seems beyond the scope of the question. Carbonyl (C double bond O) bonds will draw electrons toward them. This will pull electrons toward the C and away from the O-H. That polarity makes the O-H bond weaker, and leads to loss of the H as an acidic proton.

Thanks for the help. You pretty much clarified what I ended up doing. If you notice further down the page I corrected my drawing, because I f*cked up ;).

I eventually went with the 120 degree bond angles :)

I think tetrehedral is 107? Maybe..

I think I wrote the bond thing later on too, so I got that right. I mentioned attraction and such between the electrons.

I know about polarity, and the such. I know what you mean about being out of the scope of the question. It was an assignment about hybridization, so it was supposed to only ask hybridization stuff.

Yeah, I think it IS actually 107 or less because lone pairs takes up more space than regular atom .

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