Calcium nitrite Property

Melting point:

390 °C

Density 

2.23

refractive index 

n20/D 1.3946

Flash point:

110 °C

solubility 

slightly soluble in ethanol

form 

white-yellow hexagonal crystals

color 

white-yellow hexagonal, hexane crystals, crystalline; hygroscopic

Water Solubility 

slightly soluble alcohol [MER06]; g/100g solution H2O: 38.3 (0°C), 43.0 (18.5°C), 71.2 (91°C); solid phase Ca(NO2)2 · 4H2O (0°C, 18.5°C), Ca(NO2)2 ·2H2O (91°C) [KRU93]

Merck 

13,1688

LogP

-2.52 at 20℃

CAS DataBase Reference

13780-06-8(CAS DataBase Reference)

EPA Substance Registry System

Calcium nitrite (13780-06-8)

Safety

Safety Statements 

23-24/25

WGK Germany 

3

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H301Toxic if swalloed

H318Causes serious eye damage

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P270Do not eat, drink or smoke when using this product.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P301+P310IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P310Immediately call a POISON CENTER or doctor/physician.

P321Specific treatment (see … on this label).

P330Rinse mouth.

P405Store locked up.

P501Dispose of contents/container to..…

Calcium nitrite Chemical Properties,Usage,Production

Description

Calcium nitrite has the formula of Ca(NO2)2 and the molecular weight of 132.0894 g/mol. It can be made by the usual double decomposition reaction of sodium nitrite and CaCl2. It forms a tetrahydrate that is isomorphous with the strontium and barium salts:
2Na2NO2 (aq) + CaCl2 ? Ca(NO2)2 (aq) + 4NaCl (aq)

Chemical Properties

white or yellowish deliquescent, hexagonal crystal(s); prepared from nitric oxide and a mixture consisting of calcium ferrate and calcium nitrate; used to inhibit corrosion in lubricants and concrete [MER06]

Physical properties

Calcium nitrite, Ca(NO2)2, has the CAS number of 13780-06-8 and occurs as yellow-white crystals. It is very hygroscopic. Its density is 2.23 g/cm³ and it decomposes at 392°C to form nitrogen oxides and CaO. It is slightly soluble in alcohol. Ca(NO2)2·4H2O loses two waters of hydration at about 80°C and one at 105°C to form the monohydrate. It loses the other at about 155°C. The anhydrate, if further heated, is unstable and oxidizes to the nitrate in air above 220°C:
Ca(NO2)2 + O2 + heat?Ca(NO3)2

Uses

Calcium nitrite has several industrial uses:
1. Calcium nitrite has high solubility, so can be used as a solution or powder in concrete as an “anti-freeze” during winter months as needed. Using this antifreeze at negative temperature can promote the hydration of minerals in cement, and the freezing point of operative temperature can be reduced to –25°C.
2. This salt is a steel rust inhibitor: calcium nitrite can clean steel and protect it from rust, and can protect steel material in concrete used to construct buildings and structures, to extend the useful life of concrete in buildings.
3. In concrete, Ca(NO2)2 acts as a coagulator: calcium nitrite is free of chlorine and alkali, capable to reduce alkali aggregation of concrete and improve its early strength and compressive resistance. The calcium nitrite protects steel reenforcing bars from chlorideinduced corrosion. One advantage to calcium nitrite is that its protection mechanism is well defined. Data are known that show the levels of chloride to which given levels of calcium nitrite will protect. Once corrosion initiates, the rates are lower with calcium nitrite present. These results have been used to produce reinforced concrete structures with durability in excess of 50–100 years.
4. Calcium nitrite can be used as corrosion inhibitor when added to lubricating agents.
5. Calcium nitrite can also be used in pharmaceutical, dyes and metallurgy industries, as a mild reducing agent.

Uses

Corrosion inhibitor in lubricants, concrete.

Preparation

Industrially, calcium nitrite is manufactured by reacting “NOX” gas with “lime”:
Ca(OH)2 + NO +NO2?Ca(NO2)2 +H2O
By carefully controlling calciumnitrite conditions, the selectivity on converted lime, on a molar basis, is over 95% pure. It is soluble in water (98.2 g/100 ml at 20 °C) and the solution must be evaporated at low temperature to obtain the tetrahydrate. If heated with NO2 gas, it also form the nitrate:
Ca(NO2)2 + NO2?Ca(NO3)2 + NO
Anhydrous calcium nitrite is unstable and slowly oxidizes in air to form the nitrate. It is also soluble in alcohol at 0.97 g/100 ml at 20 °C.

General Description

Calcium nitrite solution (Ca(NO₂)₂) is widely utilized as a corrosion inhibitor. It protects the metal surface against chloride attack and increases the threshold level and improves the overall life of the concrete. Ca(NO₂)₂ does not change the mechanical properties of the cement.

Flammability and Explosibility

Not classified

Purification Methods

Crystallise it from hot water (1.4mL/g) by adding ethanol and cooling to give the hydrate. It is deliquescent. [Ray & Ogg J Am Chem Soc 79 265 1957.]