Nitrates/Sulphides

Almost all inorganic nitrate salts are soluble in water at standard temperature and pressure. A common example of an inorganic nitrate salt is potassium nitrate (saltpeter). A rich source of inorganic nitrate in the human body comes from diets rich in leafy green foods, such as spinach and arugula. NO3- (inorganic nitrate) is the viable active component within beetroot juice and other vegetables.

Nitrate salts are found naturally on earth as large deposits, particularly of nitratine, a major source of sodium nitrate. Nitrites are produced by a number of species of nitrifying bacteria, and the nitrate compounds for gunpowder (see this topic for more) were historically produced, in the absence of mineral nitrate sources, by means of various fermentation processes using urine and dung. Also, Nitrates are found in fertilizers and as a byproduct of lightning strikes in earth's nitrogen-oxygen rich atmosphere, nitric acid is produced when nitrogen dioxide reacts with water vapor.

The major application of nitrates is as oxidizing agents, most notably in explosives where the rapid oxidation of carbon compounds liberates large volumes of gases (gunpowder for an example). Sodium nitrate is used to remove air bubbles from molten glass and some ceramics. Mixtures of the molten salt are used to harden some metals.

Bismuth III Sulfide Powder: Sulfates occur as microscopic particles (aerosols) resulting from fossil fuel and biomass combustion. Some anaerobic microorganisms, such as those living near deep sea thermal vents, utilize sulfates as electron acceptors. Magnesium sulfate, commonly known as Epsom salts, is used in therapeutic baths. Gypsum, the natural mineral form of hydrated calcium sulfate, is used to produce plaster. Copper sulfate is a common algaecide. The sulfate ion is used as counter ion for some cationic drugs.

Although nitrites are the nitrogen compound chiefly used in meat curing, nitrates are used in certain specialty curing processes where a long release of nitrite from parent nitrate stores is needed. The use of nitrates in food preservation is controversial. This is due to the potential for the formation of nitrosamines when nitrates are present in high concentrations and the product is cooked at high temperatures. The effect is seen for red or processed meat, but not for white meat or fish.