Minerals and Energy Resources

Saltpeter or Potassium Nitrate – Definition, Uses, Side Effects

Saltpeter or Potassium Nitrate

Saltpeter or potassium nitrate, KNO3 is a natural mineral source found on earth. Depending on where you live, it may be spelled “saltpeter” rather than ‘saltpeter’. In the early time before systematic naming of chemicals, saltpeter has another name as nitrate of potash.

It is categorized as (1) Ordinary saltpeter, or potassium nitrate, KNO3; (2) Chile saltpeter, cubic niter, or sodium nitrate, NaNO3; and (3) Lime saltpeter, wall saltpeter, or calcium nitrate, Ca(NO3)2.

These three nitrates generally occur as efflorescence, which forms by the oxidation of nitrogenous matter in the presence of the alkalis and alkaline earth. Now we shall study briefly about the different Saltpeters.


Ordinary Saltpeter

Potassium nitrate occurs naturally on the surface of the Earth, on walls and rocks, and inside caves; and it forms in certain soils in Spain, Italy, Egypt, Iran, and India. Potassium nitrate is white in color and soluble in water; it has a vitreous luster and a cool and salty taste.

Chile Saltpeter

Sodium nitrate occurs, under the same conditions as ordinary saltpeter, in deposits covering immense areas in South America, abounding especially in the regions of Tarapacá and Antofagasta in Chile. Chile saltpeter is in use mainly in the nitric acid industry and particularly as a fertilizer.

Lime Saltpeter

On the walls of stables, calcium nitrate was once common as an efflorescence. Now we manufacture it from atmospheric nitrogen. Its main use is, in the nitric acid industry and manure works.

Properties of Potassium Nitrate

At room temperature, it has an orthorhombic crystal structure, which transforms to a trigonal system at 129 °C (264 °F). Potassium nitrate is somewhat soluble in water, but its solubility increases with temperature.

In aqueous state is almost neutral, exhibiting pH 6.2 at 14 °C (57 °F) for a 10% solution of commercial powder. It is incapable of dissolving in alcohol and is not poisonous; although it can react explosively with reducing agents, but it is not explosive on its own.

Production of Potassium Nitrate

Different processes are in use for Potassium nitrate production. In addition, one of them is combining ammonium nitrate and potassium hydroxide.

KOH (aq) + NH4NO3 (aq) → NH3 (g) + H2O (l) +  KNO3 (aq)

For industrial purpose, it is prepared using double displacement reaction between sodium nitrate and potassium chloride.

KCl (aq) + NaNO3 (aq) → KNO3 (aq) + NaCl (aq)

Uses of Potassium Nitrate

Oxidizer: Its most common use is probably as an oxidizer in black powder. Furthermore, from the most ancient times, it provided the explosive power for all the world’s firearms.

However, it remains in use today in black powder rocket motors, and also in combination with other fuels like sugars in “rocket candy”. Also in use as fireworks such as smoke bombs. It is mixed with cigarettes to maintain an even burn of the tobacco.

Food Additive: We still use potassium nitrate in some food applications, such as salami, dry-cured ham, charcuterie, and (in some countries) in the brine used to make corned beef. It is now in use as a food additive in the United States and Australia and New Zealand.

Food preparation: In West African cuisine, they widely use potassium nitrate (saltpeter) as a thickening agent in soups and stews such as okra soup and isi ewu.

It also helps a lot to soften food and reduce cooking time when boiling beans and tough meat. Saltpeter is also an essential ingredient in making special porridges, such as kunun kanwa.

Fertilizer: As Potassium nitrate is rich in nitrogen and potassium. It is in use as a fertilizer.

Pharmacology: Some toothpaste uses it for sensitive teeth. Also, it is the main ingredient for kidney tablets to relieve the symptoms of cystitis, pyelitis, and urethritis in Thailand. It also Combats high blood pressure.

Other uses: Works as an aluminum cleaner. As an Electrolyte in a salt bridge. It helps in the flowering of mango trees in the Philippines. As potassium nitrate is a good source of potassium ions, it helps for ion exchange with sodium ions in the chemically strengthened glass.

Side Effects of Potassium Nitrate

It can pose a number of health risks. When inhaled, it may cause respiratory problems, including coughing and shortness of breath. If there is skin or eye contact then it may result in irritation such as redness, itching, and pain. It can cause kidney damage or anemia, as well as headaches and digestive distress.

Solved Question for You

Q.1. Who discovered saltpeter?

Ans: around 1000 AD, some inventor in China discovered that mixing saltpeter with charcoal and sulfur made a bang.

Q. 2. Where is the largest natural source of Slatpeter located in the world?

Ans: The largest occurrence of natural saltpeter as sodium nitrate and associated compounds is in Chile’s the Atacama Desert. Moreover, it’s the Chile saltpeter, it derives from deposits of bird guano.

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