Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: aminomans on March 28, 2016, 07:51:47 PM

Title: Neutralization Reaction Problem
Post by: aminomans on March 28, 2016, 07:51:47 PM

I've been trying to solve this one for a while now.

(CH3)3SiOH + SiO2 = ______ + ______

After attempting this for hours, this is what I have:

2(CH3)3SiOH + 3SiO2 = 6CH30 + (SiOH)2Si3
This isn't what I'm looking for, since the question states that this is a neutralization reaction.

I'm trying to find the Products and Balance the equation.
I know this is a neutralization reaction.

Title: Re: Neutralization Reaction Problem
Post by: AWK on March 28, 2016, 07:58:53 PM

Magic sand is a silica coated with trimethylsilanol. No chemical reaction, only physical interactions.

Title: Re: Neutralization Reaction Problem
Post by: Enthalpy on March 29, 2016, 12:09:20 PM

https://en.wikipedia.org/wiki/Magic_sand
"...silica, exposing it to vapors of trimethylsilanol (CH₃)₃SiOH"
"Upon exposure, the trimethylsilane compound bonds to the silica particles while forming water."

https://en.wikipedia.org/wiki/Trimethylsilanol
"...used to apply hydrophobic coating on silicate surfaces. It reacts with the silanol groups of the substrate"

Both claims by Wiki suggest that HO- groups at the surface of silica react with the -OH of trimethylsilanol to form an Si-O-Si link and eliminate H₂0.

I've seen this very recently on ChemicalForums about a process for semiconductors. Something like a step to bond silicon with a polymer.

Though, the question seems to ignore end groups at the silica. "Neutralization" would then suggest the formation of a silicate. The result looks the same to my eyes, with one water molecule less.

Then, a superficial O=Si(-O-etc')-O-etc would half-open the O=Si to react with two (CH₃)₃Si-O-H, eliminate only one H₂O to create [(CH₃)₃Si-O-]₂Si(-O-etc')-O-etc.

Or even, the question expects you to seek the ester of the nonexisting diacid, then [(CH₃)₃Si-O-]₂Si0.

What I dislike about the question:
- SiO₂ is already misleading. A solid is not a single molecule. O atoms bond with two Si atoms.
- If this is really about surface reactions, it can't be understood nor written as a volume reaction.
- It ignores the transformations that preexist at the surface of any solid. The surface of silica isn't SiO₂.