Used in qualitative inorganic analysis to test for the presence of oxidizing agents, particularly in identifying nitrite ions. When added to a solution containing nitrites, stannous chloride reduces nitrite to nitrogen gas, producing a visible effervescence or color change depending on the setup. It is also employed in the detection of mercury(II) ions, where it forms a white or gray precipitate upon reduction to mercury(I) or metallic mercury. Commonly used in educational and industrial labs for simple redox testing due to its sensitivity and ease of use. Requires careful handling as it is light- and air-sensitive, often prepared fresh or stored under inert conditions.