Which of these ions may be precipitated as sulfides? Assume neutral aqueous solution, pH=7.
Silver (I) ion
Sodium ion
Calcium ion
Lead (II) ion
Manganese (II) ion
Ammonium ion
I think the silver I ion, lead II ion, and manganese ion may be precipitated as sulfides, but I'm not sure.
You need to memorize the solubility tables. Here is a simple table (it won't catch everything but it will catch most).
http://www.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html
To determine which ions may be precipitated as sulfides, we need to consider their solubility in sulfide ions (S2-) in a neutral aqueous solution (pH=7).
The solubility rules for sulfides state that most sulfides are insoluble except when paired with alkali metal (Group 1A or Group 2A) cations or ammonium (NH4+) cations. Based on these rules, we can analyze each ion to see if it will form an insoluble sulfide:
1. Sodium ion (Na+): Sodium ions are alkali metal cations, so they will not form an insoluble sulfide. Therefore, sodium ion will not precipitate as a sulfide.
2. Calcium ion (Ca2+): Calcium ions are alkaline earth metal cations, and like sodium ions, they will not precipitate as sulfides in a neutral aqueous solution. So, calcium ion will not form an insoluble sulfide.
3. Silver (I) ion (Ag+): Silver ions can form insoluble sulfides, and therefore, they may be precipitated as sulfides in a neutral aqueous solution.
4. Lead (II) ion (Pb2+): Lead ions can form insoluble sulfides, and thus, they can be precipitated as sulfides in a neutral aqueous solution.
5. Manganese (II) ion (Mn2+): Manganese ions can also form insoluble sulfides and can be precipitated as sulfides in a neutral aqueous solution.
6. Ammonium ion (NH4+): Ammonium ions are paired with sulfide ions to form highly soluble compounds (ammonium sulfide), which will not precipitate. Therefore, ammonium ion will not form an insoluble sulfide.
Based on the solubility rules, the ions that may be precipitated as sulfides in a neutral aqueous solution are: silver (I) ion, lead (II) ion, and manganese (II) ion.