In recent decades, qualitative analysis in the curriculum has declined due to the expansion of instrumental analytical chemistry; however, it should not be forgotten that the principles of qualitative analysis are the basis of the development of several instrumental analytical techniques. In this paper, the study of the behavior of some transition-metal ions in aqueous solution using some typical reactions of the qualitative analysis scheme is proposed. In this way, some of the chemical reactions in aqueous solution studied in the lecture course are observed in the laboratory, and this reinforces the understanding of these equilibria. In addition, the behavior of these metals in relation to the pH of the solution can help students understand the chemical processes related to environmental problems, such as acid rain.
García-Moreno et al. (2003) studied this question.