Simply put it is slowly adding a known amount of some substance into some unknown until a point of equivalence. At that point, assuming you can determine what that point is (usually with some color change) you can basically calculate the amount of the unknown.
They are a pain in the ass. If you ever took a chemistry class in secondary school you probably did an acid base titration with materials that look like this:
I’m doing something similar to this but not exactly, and I promise you reeeally dont want me to go full research speech on you because I literally can and often do talk about it for over an hour.))
Okay but now i'm genuinely curious about what science you actually do
Long story short I’m trying to determine the size of some really really small gold particles which do chemistry that might just save the world.
Full-ish answer under the cut. Hopefully not too jargony for anyone to understand. Featuring some images of some of my powerpoint slides that I’m quite proud of.
So Catalysts are materials that facilitate reactions, right? You may have heard of a catalytic converter in your car. Those are generally made of super super small particles, called nanoparticles of metals.
Similar metal catalysts are used to make basically everything you’ve ever used. Plastics production generally use hydrogenation (shown below) catalysts that are often Palladium poisoned with Silver.
The metal that we are looking at as a catalyst is gold! Gold or Au as I might call it, has some interesting properties that I won’t get into which might make it a viable option for Methane oxidation... And oxidizing methane, particularly to methanol could really help in stopping the depletion of the ozone layer... We arent there yet though so let me back up a bit.
Something important about catalysts are that they have to collide with whatever it is they are reacting with, right? So we as scientists want to optimize the amount that a catalyst has the opportunity to hit things, right?
SO if you have a really big nanoparticle like the one below:
you are going to be wasting all those atoms in the middle that dont have the opportunity to collide with anything! Verses if you have a bunch of small ones:
You have the same number of atoms but a lot fewer of them are wasted!
So to figure this out we usually use TEM orTransmission electron microscopy to get images of how big the catalysts are... but this has some issues like time, money, ect. So it is MY JOB to figure out another way to determine the size of these nanoparticles!
The idea is to basically do a “titration” where we fill up surface sites with something that binds easily to gold: Thiols or Sulfur groups.
As soon as we stop seeing the thiols adsorb to the surface of the gold that means the number of thiols we added filled up the gold and we can do some fancy math to determine the surface area.
