Sodium nitrite represented by the chemical formula NaNO₂ is a nitrous acid sodium salt ^[1] that is soluble in water and aqueous acid ^[4]. It is non-combustible itself but assists the burning of combustible material ^[1]. It is an ionic compound and a strong reducing agent ^[3]. In acidic solution, though, it mainly executes oxidation reactions ^[4].

Sodium Nitrite Identification
CAS Number	7632-00-0 [1]
PubChem CID	23668193 [1]
ChemSpider ID	22689 [2]
EC Number	231-555-9 [1]

Composition and Synthesis

Sodium nitrite can be prepared by heating sodium nitrate and lead ^[7].

NaNO₃ + Pb = NaNO₂ + PbO

Properties and Characteristics of Sodium Nitrite

General Properties
Molar mass/molecular weight		68.995 g/mol [1]
Physical Properties
Color/appearance		Yellowish white crystals [1]
Melting point/freezing point		271°C, 519.8°F [5]
Boiling point		320°C, 608°F (decomposes) [1]
Density		2.17 g cm-3 [5]
State of matter at room temperature (normal phase)		Solid [1]
Vapor pressure		0.2 [6]
Chemical Properties
Solubility in water		820 g/l (at 20oC) [4]
pH		9 (basic) [4]
Atomic Properties
Crystal structure	Orthorhombic [1]

Prominent Reactions

On heating ammonium chloride with sodium nitrite, initially, ammonium nitrite and sodium chloride are formed. Then ammonium nitrite decomposes into nitrogen and water ^[9].

NH₄Cl + NaNO₂ = NH₄NO₂ + NaCl

NH₄NO₂ = N₂ + 2H₂O

It reacts with concentrated hydrochloric acid under boiling condition to produce sodium nitrate, sodium chloride, nitric oxide and water ^[11].

3NaNO₂ + 2HCl = NaNO₃ + 2NaCl + 2NO + H₂O

Sodium nitrite reacts with sulfuric acid to form sodium sulfate, nitrogen dioxide, nitric oxide and water ^[12].

2NaNO₂ + H₂SO₄ = Na₂SO₄ + NO₂ + NO + H₂O

Sodium Nitrite Uses

1. In meat curing, preservation and coloring ^[1].
2. As a reagent in techniques involving analytical chemistry ^[1].
3. As a corrosion inhibitor, food additive, hog poison and an antidote to cyanide poisoning (used in combination with sodium thiosulfate) ^{[1, 4]}.
4. For the production of various dyes and fertilizers ^{[1, 4]}.
5. For bleaching fibers and printing textile fabrics ^[3].
6. As a laxative, bronchodilator and vasodilator in the medical field ^[3].

Is It Harmful

The compound is highly toxic and if ingested it may cause cyanosis, convulsions and even death. It causes digestive tract, skin and eye irritation on contact. If inhaled, it may be fatal. It can cause cancer and an explosion or fire hazard ^[6]. Repeated exposure may have an acutely poisonous effect on health. Having it during pregnancy may pose a health risk by increasing the probability of brain tumors in the baby ^[10].

Sodium Nitrite (NaNO₂) Price

The compound costs around $400 – $500 for every metric ton. The price may vary slightly across suppliers ^[8].

References
1. Sodium Nitrite – Pubchem.ncbi.nlm.nih.gov
2. Sodium Nitrite – Chemspider.com
3. Sodium Nitrite – Fearschemistry.wikidot.com
4. Sodium Nitrite – Chemicalbook.com
5. Sodium Nitrite – Americanelements.com
6. Sodium Nitrite (7632-00-0) – Chemicalbook.com
7. Preparation of sodium nitrite – Prepchem.com
8. Sodium nitrite price – Alibaba.com
9. What is the gas produced by heating ammonium chloride with sodium nitrite? – Quora.com
10. Maternal consumption of cured meats and vitamins in relation to pediatric brain tumors. – Ncbi.nlm.nih.gov
11. Sodium nitrite react with hydrogen chloride – Chemiday.com
12. Sodium nitrite react with sulfuric acid – Chemiday.com