in analytical chemistry, a chemical reaction between solids, the occurrence of which is detected by a characteristic color. Solid-state reactions also include reactions that result in the precipitation or dissolution of a colored deposit.
The procedure for carrying out analytical solid-state reactions is simple: small amounts (of the order of 1 mg) of a reagent and of the substance to be tested are mixed on a strip of filter paper or in a porcelain crucible, and the resulting color is observed. This method can be used to detect, for example, Ni2+ in its salts; here, small amounts of dimethylglyoxime and (NH4)2CO3 are added to the sample, as a result of which red dimethylglyoximine, Ni(C4H7O2N)2, is observed. Salts of Pb2+ react with KI to yield yellow Pbl2, and salts of Fe3+ react with K4Fe(CN)6 to give Prussian blue, Fe4[Fe(CN6)]3.
Solid-state reactions can be used in the field to identify minerals, ores, and chemical fertilizers. They can also be used to test pharmaceuticals.
REFERENCEVoskresenskii, P. I. Analiticheskie reaktsii mezhdu tverdymi veshchestvami i polevoi khimicheskii analiz. Moscow, 1963.
S. A. POGODIN