3 M NaOH:

Once again, the same eight aqueous, 0.2 M cation solutions were gathered, and a few drops of each reagent were put into its own test tube so that there were eight test tubes, each containing one of the cation solutions. Then, 3 drops of 3 M NaOH were added to each test tube. Aluminum nitrate, barium nitrate, nickel nitrate, and lead (ii) nitrate did not react to the NaOH. However, silver nitrate reacted with NaOH to create a dark green/brown precipitate, copper nitrate reacted to create a goopy, blue precipitate, ferric nitrate reacted to create a thick, rusty precipitate, and manganese nitrate reacted to create a creamy yellow precipitate. The net ionic equations representing each reaction, in order, are as follows:

Table 4a. Summary of what happened when 3 drops of 3 M NaOH were added to each cation.

After that, the samples from each test tube were split such that there were eight test tubes, each of which contained one of the four precipitates. 4 more drops of 3 M NaOH were added to four of the test tubes, resulting in no changes to the precipitates. To the other four test tubes, 4 drops of 6 M HNO₃ were added, resulting in all four samples dissolving into clear liquid solutions. The equations representing these reactions in order are as follows:

Table 4b. Summary of what happened after 4 more drops of 3 M NaOH were added to the solid cations.

Table 4c. Summary of what happened after 4 drops of HNO3 were added to the solid cations.