• Sodium nitrate is a common ingredient in fireworks.fireworks image by Angie from Fotolia.com
  
  Sodium nitrate, also known as Chile saltpeter or soda niter, is a naturally occurring, water-soluble salt used in fertilizers and fireworks. It occurs naturally as the mineral nitratine. It should not be confused with sodium nitrite (NaNO₂), which exhibits significantly different chemical properties.
  
  

Chemical and Physical Properties

• Sodium nitrate (chemical formula NaNO₃) forms white, odorless crystals with a density of 2.26 grams per cubic centimeter (g/cm₃). It is deliquescent, meaning that it will rapidly absorb moisture from the air.
  
  Sodium nitrate melts at 308 Celsius and decomposes at 380 Celsius. Like most nitrates, sodium nitrate will decompose explosively when heated above 500 Celsius.
  
  At room temperature, it will dissolve in water at a rate of 92.1 grams per 100 milliliters of water. It is also soluble in ammonia and most alcohols. When dissolved in water, it forms neutral (pH = 7) solutions.
  
  Sodium nitrate is a strong oxidizer, meaning that it readily transfers oxygen atoms. It will cause, for example, iron metal to rapidly rust, i.e., it will convert iron (Fe) to iron oxide (Fe₂O₃): 2 Fe + 3 NaNO₃ ' Fe₂O₃ + 3 NaNO₂
  
  

Toxicity

• The fatal dose of sodium nitrate in humans is on the order of 30 to 35 grams consumed as a single oral dose, with the exact amount depending on the person's body weight. According to the U.S. Environmental Protection Agency (EPA), sodium nitrate poses a "relatively low acute oral toxicity hazard." The EPA has placed sodium nitrate in Toxicity Category III, which means "slightly toxic, slightly irritating."
  
  

Applications

• Sodium nitrate is used extensively in agriculture as a fertilizer. Its low cost, excellent solubility in water, and relatively high nitrogen content (16% by mass) make it an inexpensive source of nitrogen.
  
  Sodium nitrate is also used as a preservative in processed meats. It is particularly effect at preserving the pink color of processed meats such as hot dogs and ham. The U.S. Food and Drug Administration (FDA) allows sodium nitrate in foods at concentrations up to 500 milligrams of sodium nitrate per kilogram of food product.
  
  In the 1800s and early 1900s, sodium nitrate was used in the manufacture of gunpowder as an alternative to potassium nitrate, also known as saltpeter. Its use in this application was phased out with the advent of smokeless powders. Sodium nitrate is still used, however, in fireworks.
  
  Sodium nitrate is also common in several fumigant pesticides, although not as a poison; it aides combustion of charcoal in fumigant cartridges.