[BUG] Calcium carbonate chemical formula is not being rendered

[cat24a]

The chemical formula on the site for calcium carbonate is not being rendered. Other chemical formulas on the website are also missing.

Steps to reproduce the behavior:

1. Go to 'Calcium carbonate'
2. Read the first sentence

Expected behavior
There should be the chemical formula of calcium carbonate. (CaCO₃)

[sebastien46]

This occurs because the article uses the chem2 Template to render the formula, which hasn't been implemented in this app yet.

You can file a template request using this repo's issue tracker's template-specific issue template.