# Enable chemistry expressions in items (on Windows 10)

I would like to enable the latex library mhchem, for formatting chemical equations and physical units, in MathJax in TAO. I have been unable to succeed in this. If anyone can help with this, I would greatly appreciate it. I'm writing below the things I have figured out and attempted, already. If someone can help me figure out the rest, I would try to update some of the documentation pages.

I needed to first enable math expressions in items:

* The article "Enable math expressions in items" has a broken link and is out of date for the most recent releases of MathJax.

* The process in this discussion worked, but it is 3-4 years old. There have been updates to MathJax since then, and I can't tell if this mathjax-shrunk is the most up to date. It does not appear to have the same file structure as the current version of MathJax.

After enabling math expressions in items, I tried to enable mhchem. I did the following things:

* I downloaded mhchem.js and copied it to C:\xampp\htdocs\taoQtiItem\views\js\mathjax\extensions.

* I changed the config (C:\xampp\htdocs\taoQtiItem\views\js\mathjax\config\TeX-AMS-MML_HTMLorMML-ful.js) file to include:

MathJax.Ajax.config.path["mhchem"] =

"https://cdnjs.cloudflare.com/ajax/libs/mathjax-mhchem/3.3.2";

MathJax.Hub.Config({

TeX: {

extensions: ["[mhchem]/mhchem.js"]

}

});

as per the github mhchem page.

Alternatively, I copied mhchem.js to:

* C:\xampp\htdocs\taoQtiItem\views\js\mathjax\extensions\ and added "[MathJax]/extensions/mhchem.js" to the config file

or

* C:\xampp\htdocs\taoQtiItem\views\js\mathjax\extensions\TeX\ and added "[MathJax]/extensions/TeX/mhchem.js" to the config file

or

* C:\xampp\htdocs\taoQtiItem\views\js\mathjax\extensions\MathML\ and added "[MathJax]/extensions/MathML/mhchem.js" to the config file

This page has some instructions on loading mhchem within MathJax, but I can't figure out how it applies, especially since the mathjax-shrunk is not the same as MathJax that is up to date according to the instructions on the nodejs extensions page.

## Comments

I also tried installing NodeJS and npm, and then installing mathjax.js with npm. I then copied the es5 folder into the mathjax folder, but that didn't enable mathjax within TAO. If I had been able to include mathjax through adding the es5 folder, then instructions exist for including mhchem in mathjax. The instructions don't transfer to including it with mathjax-shrunk, that worked to get mathjax working in TAO.