Elucidating Different Identities of Cations Essay

The solution that was being investigated in the experiment contained a mixture of positively charged ions that could only be known through the adoption the right separation approaches. In fact, specific cations could be known by carrying out confirmatory tests. With regard to the experiment, the cations could give certain colors, solutions or insoluble compounds.

When cations react with anions, they form salts that occur because of their differences in energy levels, which result in reduction and/or oxidation events. Based on the characteristics positively charged ions, it is important to note that the experiment was conducted because cations could be classified into six categories. For each category, a general reagent was used to isolate its members from the mixture. In fact, the categorization was important because it enabled the reactions to be carried out using a sequence.

The sequence prevented some ions from reacting with multiple reagents, a situation that could lead to a high level of ambiguity. It was noted that the cationic analysis adopted by the experiment was based on the testing of the solubility products of salts formed through various reactions. The reactions exhibited in the practical indicated that the following compounds appeared as precipitates:

• Al (OH)³(s)
• Ca(OH)²(s)
• Cu(OH)²(s)
• AgCl(s)
• Fe(OH)³(s)
• PbCl²(s)
• Zn(OH)²(s)

Although the above cations formed solids, they could be exposed to further reactions to evaluate their reactivity patterns with different reagents.

In order to separate Ag⁺ from other cations that formed precipitates in the first reaction, it was important to add ammonia to the solution containing the insoluble compounds. Ag⁺ ions were identified because its AgCl(s) was able to disappear in the presence of ammonia to form a clear solution. It was also important to test whether Pb²⁺ ions were present by attempting to dissolve PbCl²⁺ precipitate in ammonia. The failure to dissolve implied that Pb²⁺ ions were present in the mixture.

It was expected that Al³⁺ and Zn²⁺ ions could form precipitates after the addition of three drops of NaOH(aq). However, they could re-dissolve after adding excess NaOH(aq). The compounds involved were Al(NO3)³ and Zn(NO3)². On the other hand, some cations could form precipitates with a few drops of NaOH(aq), but they could not re-dissolve the incorporation of excess NaOH(aq) into the test tube. The cations were Ca²⁺ and Cu³⁺ while the salts involved were Ca(NO3)² and Cu(NO3)³.

A few drops of ammonia and the excess ammonia solution were also utilized to identify cations in the experiment. Essentially, the formation of a blue precipitate through the incorporation of a few drops of ammonia solution into the test tube implied that Cu²⁺ cations were present in the mixture. However, the metal solute dissolved when excess aqueous ammonia was added. However, it was notable that solutes formed by other cations could not dissolve when copious amounts of ammonia solution were added.

The cations were Fe³⁺ (appeared as a greenish precipitate) and Fe³⁺, Zn²⁺, Pb²⁺, Ca²⁺, Al³⁺ (all appeared white). Frequently, Ag⁺ and Cu²⁺ are difficult to separate. However, the experiment used a simple test to ensure that the two cations were distinguished. In brief, HCl(aq) was added to the solution. The ions could be identified because Cu²⁺ ions could not form a precipitate while Ag⁺ could be seen as a white solid.

Overall, the experiment was important in elucidating different identities of cations that were found in a mixture of unknown chemical constituents.