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.
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