Let’s start by creating a set of species that we want to take part in a reaction.
Now let’s create a reaction using these species. The reaction arrow can be entered via the Chemistry package palette or using the shortcut <Esc>rxn<Esc>. Do not enter the reaction arrow using the built-in Mathematica™ shortcut <Esc>–><Esc>, as that arrow will not include the chemistry-specific associations. Add the chemical species using the palette we created above.
Notice that the hydronium ion in this particular reaction appears on both sides of the reaction (i.e., it is a catalyst). In some contexts (e.g., chemical kinetics) it is important to retain that species in the reaction expression. In others, you really care more about the net reaction. You can create the net reaction using the function ReduceReaction.
Reactions can also be manipulated algebraically, through addition, subtraction, multiplication by a constant, and division by a constant.
Chemical reactions can be queried for a variety of aspects that you can use in your own calculations.