3.0 M NH₄OH:

After eight more samples of eight different aqueous, 0.2 M cation solutions were gathered into eight different test tubes, 3 drops of 3.0 M aqueous ammonia (NH₄OH) were added to each tube. The silver nitrate, barium nitrate, and copper nitrate solutions stayed clear, indicating that no reaction had occurred. However, the aluminum nitrate reacted with the NH₄OH to form an opaque white precipitate, ferric nitrate reacted to form a slightly chunky, red-brown precipitate, manganese nitrate reacted to create a precipitate that looked like curdled milk, nickel nitrate reacted to form a cloudy teal precipitate, and lead (ii) nitrate reacted with NH₄OH to create a milky white precipitate. The net ionic equations for each, in order, are as follows:

Table 5a. Summary of what happened when 3 drops of 3 M aqueous ammonia were added to each cation.

The precipitates were washed and centrifuged until most of the liquid supernatants had been removed and disposed of. Then, a 15 M aqueous ammonia solution was added to the precipitates. The iron (iii) hydroxide, aluminum (iii) hydroxide, manganese (ii) hydroxide, and lead (ii) hydroxide precipitates did not react to the 15 M NH₄OH. However, the nickel (ii) hydroxide reacted with 15 M NH₄OH to form a clear, blue aqueous solution, though it didn’t fully react because some of the nickel (ii) hydroxide remained as a solid. It is represented by the following net ionic reaction:

Table 5b. Summary of what happened when 3 drops of 15 M aqueous ammonia were added to each solid cation precipitate.