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Potassium Nitrite

Potassium nitrite represented by the chemical formula KNO2 is a yellowish white crystalline and deliquescent powder that is soluble in water, alcohol and liquid ammonia [1]. It is a potassium salt and an ionic compound [1, 3]. KNO2 is a strong oxidizer and incompatible with strong acids, strong reducing agents, cyanides, ammonium salts and combustible materials [6].

Potassium Nitrite

Potassium Nitrite Identification

CAS Number 7758-09-0 [1]
PubChem CID 516910 [1]
ChemSpider ID 22857 [2]
EC Number 231-832-4 [1]

How to Make It

Potassium nitrite can be prepared by heating potassium nitrate with lead.

KNO3 + Pb = KNO2 + PbO

If you want, you can use zinc or copper instead of lead [5].

Potassium Nitrite Formula

Properties and Characteristics of Potassium Nitrite

General Properties

Molar mass/molecular weight 85.103 g/mol [1]

Physical Properties

Color/appearance White or slightly yellow crystals [1]
Melting point/freezing point 441°C, 825.8°F [1]
Boiling point 537°C, 998.6°F [1]
Density 1.9 g cm-3 [1]
State of matter at room temperature (normal phase) Solid [1]
Heat capacity 107.4 J/mol K [1]
Specific gravity 1.915 [6]

Chemical Properties

Flammability Yes [4]
Solubility in water 3120 g/l (at 25oC) [1]
pH 8.40 (basic) [3]

Potassium Nitrite Structure

Prominent Reactions

A reaction between potassium nitrite and concentrated nitric acid produces potassium nitrate, nitrogen dioxide, nitric oxide and water [7].

2KNO2 + 2HNO3 = 2KNO3 + NO2 + NO + H2O

A saturated solution of KNO2 reacts with concentrated sulfuric acid to produce potassium sulfate, nitrogen dioxide, nitric oxide and water [8].

2KNO2 + H2SO4 = K2SO4 + NO2 + NO + H2O

Potassium nitrite reacts with concentrated hydrochloric acid to form potassium nitrate, potassium chloride, nitric oxide and water [9].

3KNO2 + 2HCl = KNO3 + 2KCl + 2NO + H2O

Potassium Nitrite Uses

  1. To make other chemicals, heat transfer salts [1, 6].
  2. In chemical analysis [1].
  3. As a food additive (preservative), in fertilizers [4].
  4. As an antidote to cyanide poisoning [4].
  5. As a vasodilator in the medical field [4].
  6. As an anti-scaling agent and corrosion inhibitor [6].

Is It Dangerous

It is a poison if ingested. It may cause explosion hazard if heated. The compound begins decomposing at 350°C and emits toxic fumes of potassium oxide. KNO2 in food can increase the risk of cancer [1, 4].

Potassium Nitrite Price

10 gram of the compound costs around $19.2 [6].

References:

  1. Potassium Nitrite – Pubchem.ncbi.nlm.nih.gov
  2. Potassium Nitrite – Chemspider.com
  3. What is the pH of a 0.25M solution of potassium nitrite? – Quora.com
  4. Potassium Nitrite – Chemicalbook.com
  5. Preparation of potassium nitrite – Prepchem.com
  6. Potassium Nitrite – Chemicalbook.com
  7. Potassium nitrite react with nitric acid – Chemiday.com
  8. Potassium nitrite react with sulfuric acid – Chemiday.com
  9. Potassium nitrite react with hydrogen chloride – Chemiday.com

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