What is Potassium Nitrate

Potassium nitrate is also known as Saltpeter is a chemical compound with formula of KNO3. This compound is popularly used as a fertilizer as it has two major elements for plant nutrients, which are nitrate and potassium. In nature, potassium nitrate occurs as a mineral, niter. It is odorless, moderately soluble in water, and has a white solid or powdery form. In addition, the solubility of potassium nitrate in water increases with temperature.

Manufacturing Process

  • Combining ammonium nitrate (NH4NO3) and potassium hydroxide (KOH)

In earlier times, potassium nitrate was obtained from natural mineral sources and from caves. Nowadays the production of potassium nitrate is done by making ammonium nitrate react with potassium hydroxide.

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

  • Combining ammonium nitrate (NH4NO3) and potassium chloride (KCl)

From the first method of combining ammonium nitrate and potassium hydroxide produces a by-product of ammonia. Thus, an alternative way to produce potassium nitrate without producing ammonia is through the reaction between ammonium nitrate and potassium chloride as shown below;

NH4NO3 (aq) + KCl (aq) → NH4Cl (aq) + KNO3 (aq)

  • Neutralizing nitric acid (HNO3) with potassium hydroxide (KOH)

KOH (aq) + HNO3 → KNO3 (aq) + H2O (l)

  • Double displacement reaction

Potassium nitrate is produced by a double displacement reaction between sodium nitrate and potassium chloride on industrial scale.

KOH (aq) + HNO3 → KNO3 (aq) + H2O (l)

The Uses of Potassium Nitrate

  • Fertilizer

Potassium nitrate is a very potential fertilizer as it is highly soluble and chloride free nutrient source. The nitrate can be immediately absorbed by the plant, thus there is no additional microbial action and soil transformation required. Potassium nitrate also contains a high proportion of potassium, which is highly needed by the crops with the ratio of nitrogen to potassium of 1:3.

  • Oxidizer

Potassium nitrate is also very famous for its use as oxidizer in blackpowder, which provides the explosive power. Besides that, cigarettes also use potassium nitrate to maintain an even burn of tobacco.

  • Nitric acid production

 Potassium nitrate is used to produce nitric acid by combining sulfuric acid with nitrate such as saltpeter. Nowadays, the reaction could be reversed using the Ostwald process.

  • Food preparation

Potassium nitrate (saltpeter) is also known for its usage as thickening agent in soups and stews. Besides that, it also can soften food and reduce the cooking time.

  • Other application

Potassium nitrate is also used as a diuretic in medicine, an ingredient of toothpaste for sensitive teeth, and ingredient for back and joint pain medicine.

Product Identification

Physical and Chemical Properties