Untitled - Kelly Walsh High School

52 CHEMISTRY FOR THE UTTERLY CONFUSED
Don’t Forget!
Don’t Forget!
General solubility rules for the commonly encountered ions:
• All salts of Group IA (Na , K , and so on) and the ammonium ion (NH4 )
are soluble.
• All salts containing nitrate (NO3 ), acetate (CH3COO ), and perchlorate
(ClO4 ) are soluble.
• All chlorides (Cl ), bromides (Br ), and iodides (I ) are soluble except those
of Cu , Ag , Pb2 2 , and Hg2 .
• All salts containing sulfate (SO 4 2 ) are soluble except those of Pb 2 , Ca 2 ,
Sr 2 , and Ba 2 .
Salts containing the following ions are normally insoluble:
2 3 • Most carbonates (CO3 ) and phosphates (PO4 ) are insoluble except those
of Group IA metals and the ammonium ion.
• Most sulfides (S2 ) are insoluble except those sulfides composed of Group IA
and IIA metals or the ammonium ion.
• Most hydroxides (OH ) are insoluble except those of Group IA metals, calcium,
strontium, and barium. (Later we will see that these are strong bases.)
• Most oxides (O2 ) are insoluble except for those of Group IA and Group IIA
metals, which react with water. (These will produce strong bases.)
You must know solubility rules in order to predict whether or not precipitation
will occur.
You should only apply the solubility rules to combinations of ions.
Let’s consider the following problem as an example of how you might apply
these rules. Suppose a solution of lead(II) nitrate is mixed with a solution of
sodium iodide. Predict what will happen.