High-Tc Superconducting QUantum Interference Devices (SQUIDs) have been used to detect magnetic fields produced by a variety of chemical reactions. We call this phenomenon chemomagnetism. Reactions studied thus far include solid-gas reactions (metal oxidation during solid combustion), solid-liquid reactions (between metals and acids or bases), liquid-liquid (acid-base reactions), and replacement reactions (liquid-solid and liquid-liquid). The observed chemomagnetic fields are most likely generated by the flow of ions and electrons during the intermediate processes of a typical reaction, and often exhibit complex temporal behavior. The time-dependence of these fields, and their magnitudes, depend on the specific chemical reactions and reactant concentrations. For example, chemical reactions involving the oxidation of metals from the same row of the periodic table generate similar time-dependent magnetic signals. We also observe the formation of permanent magnetic fields during the synthesis of ferromagnetic materials. SQUIDs may prove to be important tools for noninvasively studying the dynamics of chemical reactions.
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