Microscale Procedure for Inorganic Qualitative Analysis with Emphasis on Writing Equations: Chemical Fingerprinting Applied to the n-Bottle Problem of Matching Samples with Their Formulas

• Autores: Prem D. Sattsangi
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 91, Nº 9, 2014, págs. 1393-1400
• Idioma: inglés
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• Resumen

  • A laboratory method for teaching inorganic qualitative analysis and chemical equations is described. The experiment has been designed to focus attention on cations and anions that react to form products. This leads to a logical approach to understand and write chemical equations. The procedure uses 3 mL plastic micropipettes to store and deliver the samples. All tests are performed on a plastic sheet that covers a template using one drop each of the sample and the reagent. The entire experiment consists of four parts: (i) Acid-Base Properties of Twelve Solutions, (ii) Survey of Chemical Reactions and Writing of Equations, (iii) Identification of Eight Unknown Samples, and (iv) Matching of a Set of Five Samples with their Respective Formulas.

    Schemes of analyses utilize the acid-base properties, the chemical reactions of cations and anions, and the solubility of compounds formed to make the identification easy. During the binary mixing of a diverse set of 12 colorless compounds, it was observed that each sample has a unique chemical fingerprint specific to the particular set. This chemical fingerprint was used in matching a set of five compounds with their chemical formula. This experiment is suitable for instruction to first-year college students and can also be used in second-year or advanced-placement (AP) high school chemistry classes. There are no hazards associated with this experiment. This contribution is part of a special issue on teaching introductory chemistry in the context of the advanced placement chemistry course redesign.