Cation Confirmatory tests:

To positively confirm the identities of all eight cations, each cation solution was subjected to a specific reagent that caused it to react in a unique way.

To start, two drops of 1.0 M aqueous potassium thiocyanate (KSCN) were added to three drops of 0.2 M aqueous ferric nitrate inside of a test tube, resulting in an aqueous solution that turned dark, blood red. The net ionic equation for this reaction is as follows:

A scoopula tip of sodium bismuthate (NaBiO₃) was mixed with 2 drops of 6 M HNO₃ to create a solution that was added to three drops of manganese nitrate inside of a test tube. The resulting reaction created a purple-tinted dark brown precipitate inside of an aqueous solution. The liquid was washed and centrifuged out of the precipitate. The net ionic equation for this reaction is as follows:

A few drops of 0.2 M aqueous lead (ii) nitrate was submerged in a hot bath. Once the lead (ii) nitrate solution had warmed up, 2 drops of 1 M potassium iodide (KI) were added to the solution, resulting in the formation of a thick, egg yolk yellow precipitate. The net ionic equation for this reaction is as follows:

2 drops of 1 M KI were added to a few drops of 0.2 M aqueous copper nitrate solution, resulting in a muddy, green-brown precipitate. The net ionic equation for this reaction is as follows:

Three drops of a 0.2 M aqueous silver nitrate solution were put inside of a test tube. Then, three drops of 15 M aqueous ammonia, three drops of 6 M aqueous HNO₃, and three drops of aqueous 1.0 M sodium thiosulfate (Na₂S₂O₃) were added to the solution. Each time a reagent was added to the silver nitrate solution, the resulting reaction was a smoky, exothermic reaction, but the aqueous solution within the test tube stayed clear the whole time. The net ionic equations for each reaction, in order, are as follows:

Three drops of 0.2 M aqueous barium nitrate were put into a test tube along with three drops of potassium chromate (K₂CrO₄), resulting in a milky, yellow precipitate. The net ionic equation for this reaction is as follows:

A drop of 0.2 M aqueous aluminum nitrate was put on a piece of litmus paper, to get an initial pH of 4. Four drops of aluminon  were added to three drops of the aluminum nitrate solution in a test tube. Then, a solution of 15 parts deionized water to one part 6 M HNO₃ was made and then used to bring the aluminum nitrate solution’s pH to 8. The resulting precipitate was an orange-red color. The net ionic equation for this reaction is as follows:

Lastly, three drops of all eight cation solutions, including 0.2 M aqueous nickel nitrate, were adjusted to a pH between 8-9, before three drops of dimethylglyoxime (C₄H₈N₂O₂) were added. The results and equations are as follows:

Nickel nitrate:  = gelatinous red/pink precipitate.

Barium nitrate: Clear solution, no reaction.

Copper nitrate:  = thick, camo green precipitate.

Silver nitrate:  = muddy lake brown precipitate.

Lead (ii) nitrate:  = banana shake yellow.

Manganese nitrate:  = chocolate brown.

Ferric nitrate:  = rusty orange.

Aluminum nitrate: Clear solution, no reaction.

The results from the cation confirmatory tests were organized in Table 7 below.

Table 7. Summary of results from cation confirmatory tests.