Is there a site on ChemSE to practice mhchem and mathjax? Or does one just learn while asking or answering a question.
We have a couple of posts on meta where you can add an answer and edit as you wish. The first one has been closed because of the large number of answers, which makes editing very difficult as MathJax takes a long time to render. The second one may be found here:
There is some guidance on how to use MathJax/mhchem: