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

0.2*22.989768+35.4527=40.0507

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

22.989768+35.4527+0.5*(2*1.00794+15.9994)=67.4501

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.

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