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In the present work, our experience with a new methodology for separation and characterization of carbonate, phosphate and chromate anions is discussed. Since 2014 this laboratory experiment has been applied in undergraduate Chemistry courses in University of Lavras, Brazil, has shown to be satisfactory along Qualitative Inorganic or Analytical courses. In order to understand and to discuss the experiment, concepts involving equilibria of precipitation, acidity and basicity, liquid-liquid extraction, as well as the notions of solubility, phases distribution of solutes, and distribution diagram of the species were explored.

Cost of lining reservoirs, whether for storage or water treatment, can be made it with different materials. As these structures have a relatively large surface area the investment amount can be economically unfeasible. A sustainable alternative method that can be used is the reduction of water infiltration in the soil, carried out through the use of a chemical dispersant such as Sodium Hydroxide (NaOH). Therefore, the aim of the present research was to define the lower NaOH concentration and volume to be applied in samples of a Red Latosol in the southern region of Minas Gerais state, Brazil. The samples, in triplicate, were treated with 5 NaOH concentrations (0, 5, 10, 15 and 30 g L -1 ) and 3 volumes per square meter application (5, 15 and 25 L m -2 ), submitting it to saturated hydraulic conductivity in constant head permeameters tests. The results showed that the application of different concentrations of NaOH reduced the saturated hydraulic conductivity in relation to the control treatment. The ratio of condutivity to NaOH concentration is best represented by the cubic regression y = 22.46 -6.06x + 0.45x² -0.01x³ (r² = 0.97). Regarding the different application rates, the difference was not significant indicating equality between the treatments analyzed. Therefore, the use of the 5 g L -1 of NaOH, applied at 5 L m -2 , was economically more feasible and could therefore be a low-cost lining alternative. v. 11(2): 199-205, 2017 200 (5, 15 e 25 L m -2 ), sendo as mesmas submetidas a testes de condutividade hidráulica saturada em permeâmetros de carga constante. Os resultados encontrados permitiram concluir que a aplicação das diferentes concentrações de NaOH reduziram a condutividade hidráulica saturada em relação a testemunha. A relação da mesma em função da concentração de NaOH é melhor representada pela regressão cúbica y = 22,46 -6,06x + 0,45x² -0,01x³ (r² = 0,97). Em relação as diferentes taxas de aplicação, a diferença não foi significativa indicando igualdade entre os tratamentos analisados. Logo, a utilização do dispersante NaOH na concentração 5 g L -1 , aplicada em 5 L m -2 , mostrou-se economicamente mais viável, podendo assim ser uma alternativa de revestimento de baixo custo. KeywordsPalavras-chave: condutividade hidráulica saturada, hidróxido de sódio, infiltração da água, Latossolo Vermelho distroférrico, revestimento alternativo.