Reef Chemistry Question of the Day #163 Unknown Molecule

[Randy Holmes-Farley]

The molecule shown below in a 3D diagram is shown in two different forms, both of which are present in normal reef aquaria.

What is the most likely identity of this molecule?

A. Ammonia/ammonium
B. Borate/Boric Acid
C. two forms of phosphate
D. Nitrate and nitrite
E. Bicarbonate/carbonate

Good luck!

























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[Randy Holmes-Farley]

oops, I'll have to get the picture fixed later.

 

[Randy Holmes-Farley]

Should be good to go!

 

[Tanggirl12]

A
NH4, NH3

 

[omykiss001]

I'm gonna go with B only

one that makes sense to me given the 2 forms presented.

 

[Lynn52]

The colors are not what I am used to for atoms. Assuming each colored ball is an atom and that the blue are H and the Red are O I'm going to go with B as well. Too many atoms for the others. My inorganic chemistry is pretty rusty, so much for that Chemistry degree I never use.

 

[nervousmonkey]

B. Borate and boric acid, if the blue colored balls are representative of hydrogen.

 

[SethOF]

A. Ammonium/ Ammonia

 

[Cory]

Not sure. But how can you tell without an elemental description on the atoms?

 

[JimWelsh]

Not sure. But how can you tell without an elemental description on the atoms?

You can infer. For example, the small blue atom is most likely hydrogen. That would make the larger red atoms oxygen, so the red/blue combinations are hydroxyl functional groups (OH-).

Of the choices presented, only "B. Borate / Boric Acid" makes sense, given the tetrahedral OH- configuration shown on the left.

 

[SethOF]

Upon closer inspection, I think the correct answer is B. Borate/Boric Acid. The colored ball represent different atoms, borate has 3, ammonia has only 2

 

[Taservices]

B. for the simple matter that the shape fits correctly and it is the only option that is made up of 3 unique atoms as per the diagram.

 

[Cory]

You can infer. For example, the small blue atom is most likely hydrogen. That would make the larger red atoms oxygen, so the red/blue combinations are hydroxyl functional groups (OH-).

Of the choices presented, only "B. Borate / Boric Acid" makes sense, given the tetrahedral OH- configuration shown on the left.

Thats cool. What is the big yellow one, an atom? Theres only one of those.

 

[Taservices]

Thats cool. What is the big yellow one, an atom? Theres only one of those.

The big yellow one would be an atom of boron, the red ones of oxygen, the blue ones hydrogen in this context.

 

[Cory]

The big yellow one would be an atom of boron, the red ones of oxygen, the blue ones hydrogen in this context.

So the others dont have a big central atom? Ammonia and the others?

 

[Taservices]

So the others dont have a big central atom? Ammonia and the others?

They do, In ammonia/ammonium case that central atom would be nitrogen. The issue isn't the central atom, it is with the small blue ones on the outer edge.

All the options could be correct if it wasn't for that layer of blue atoms.

the diagram has three unique atoms

Ammonia/ ammonium has 2 : nitrogen and hydrogen

phosphate has 2 : phosphorus and oxygen

nitrate and nitrite have 2 : nitrogen and oxygen

bicarbonate/ carbonate have 2 : carbon and oxygen

borate/boric acid has 3 : boron, oxygen, and hydrogen ........................WINNER



........although now that I think of it borate only has 2...... boron and oxygen, but in boric acid form it has all three......

this raises a bit of a wrinkle since both diagrams have an outer shell of atoms.



Possible but unlikely solution: If for whatever reason the blue sphere represents free bonding sites on an oxygen (which is weird as all hell btw) I think E would be the answer as it is <i>possible<i/> that the diagram on the right not having a visible blue sphere on all red spheres could represent a double bond in the carbonate form (and thus no free bonding site). I think it is more likely though that there is a blue sphere just oriented behind the rightmost red sphere.

 

[JimWelsh]

I think it is more likely though that there is a blue sphere just oriented behind the rightmost red sphere.

+1

 

[jason2459]

Not sure. But how can you tell without an elemental description on the atoms?

By reading his articles...


B

 

[Randy Holmes-Farley]

So the others dont have a big central atom? Ammonia and the others?

This can be a fairly difficult question. I've been surprisingly impressed with the discussion so far.

From the shapes and arrangements, one can make certain conclusions that rule out one or another of the choices, even without knowing the atom identities.

So, for example, molecules of the form AB3 can have a number of different arrangements. It can, for example, be planar (flat) with the A in the middle and the B's around it. Or it can have the A at the top of a pyramid, and the B's all below it. That is one way to distinguish NH3 from B(OH)3, even if one cannot distinguish the atoms themselves.

 

[Randy Holmes-Farley]

For those who like to totally cheat on such questions (and don't do this if you want to figure it out yourself), you can right click on pictures like the one above, and search google for the image. It is in one of my articles.