ChemCalc+ is a free app that takes the form of a snazzy calculator --- but the controls are for chemical equations instead of mathematical ones.

The interface is uncomplicated and intuitive, the features arranged and made accessible via a sidebar. With this app, you can explore and discover chemical substances and formulas, peruse chemical reactions and find specific codes, possess a handy archive of chemical terms - which you can simply open whenever you need to search up something you haven't yet heard before, produce chemical substance formulas with a click of a button, study structure formulas and ions, assess the solubilities of salt, and consult the accessible, integrated periodic table in case you forget some of its finer details.