Nitrate test to 2.5 micrograms and a concentration of 1 in 25,000 parts. Devarda's alloy (Copper/Aluminium/Zinc) is a reducing agent. When reacted with nitrate in sodium hydroxide solution, ammonia is liberated. The ammonia formed may be detected by its characteristic odor, and by damp red litmus paper's turning blue, signalling that it is an alkali — very few gases other than ammonia evolved from wet chemistry are alkaline. Aluminium is the reducing agent in this reaction that will occur. Diphenylamine may be used as a wet chemical test for the presence of the nitrate ion. In this test, a solution of diphenylamine
Precipitation (chemistry) processes are often used in sequence – for example, a barium nitrate solution will react with sulfate ions to form a solid barium sulfate precipitate, indicating that it is likely that sulfate ions are present. Digestion, or "precipitate ageing", happens when a freshly formed precipitate is left, usually at a higher temperature, in the solution from which it precipitates. It results in cleaner and bigger particles. The physico-chemical process underlying digestion is called Ostwald ripening. Precipitation (chemistry) Precipitation is the creation of a solid from a solution. When the reaction occurs in a liquid solution, the solid formed is called