Identifying Cations and Anions with solubility data

[bibbca]

I'm mostly leaving this issue here so I don't forget to write some future code.

Currently, in chemistry.php there is no way to select a random cation or anion with solubility information using the functions chem_randcation() or chem_randanion().

My proposed solution is to include an attribute to cations and anions in the global cation and anion arrays, or in the chem_compounds array. such as
array('F',1,'fluoride','','s','solubility'),
Then, modifying chem_randcation() and chem_randanion() to look for the solubility attribute.

But if someone has a better approach, I'm all for it.

[bibbca]

Also, while we're in there we need to push chem_getsolubility into allowedmacros and add a link into chemistry.html

[drlippman]

Are you thinking of adding a additional optional argument to chem_randcation that would indicate we only want values with solubility? How are you thinking it would handle cases where solubility is only known for some cation/anion pairs?

[bibbca]

Question #818693 in MOM used a smaller cation/anion list that worked together, as well as OpenStax Chemistry Textbook. Maybe a smaller randcation change with a smaller list of allowed cations/anions is the way to go?