Using Brackets

See also Entering Formulas.

A formula may contain brackets to "weight" specific parts of a compound relative to the other parts. For example

[.2Na]Cl would have a weight of


and NaCl-[.5H2O] would have a weight of:


A colleague of mine requested this feature for the purpose of trying to figure out if a compound he had synthesized and sent off for elemental analysis had a little bit of water in it (hadn't been completely dried), as in C6H6-[.1H2O], to see if the theoretical percent composition data would better match the actual lab results.

NOTE: The percent solver feature will perform this operation for you.

In earlier versions, decimal numbers could only be used after brackets and not after closing parentheses or after a dash, however this restriction has now been removed. Therefore, the above example could have also been entered as (Na).2Cl or Na.2Cl or even Cl-.2Na

If you would like brackets, [ and ], to be treated like regular parentheses, you can change this option in the Program Preferences Window. However, when brackets are being treated as parentheses, all percent solver features will be disabled.

Back to the Molecular Weight Calculator download page