strontium nitrite

Description

Strontium nitrite has the formula of Sr(NO2)2 and the molecular weight of 179.6311 g/mol. It can be made by the usual double decomposition reaction of sodium nitrite and SrCl2. It forms a tetrahydrate which is isomorphous with the calcium and barium salts:
Na2NO2 (aq) + SrCl2 ? SrNO2 (aq) + 2NaCl (aq)
If strontium nitrite is added to a mixture of magnesium– strontium nitrate, normally used in pyrotechnic formulations, it prevents aging of the nitrate mixture in the presence of water until usage in fireworks. Studies by isothermal microcalorimetry show that the addition of strontium nitrite to a 50% magnesium–50% strontium nitrate composition eliminated the induction reaction normally observed in closed ampoule studies in air at 50 C and relative humidity in the range 65–69%.

Chemical properties

white or yellowish powder(s); hygroscopic needles [HAW93]

Physical properties

Anhydrous strontium nitrite, Sr(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 >650°C to form nitrogen oxides and SrO. It is slightly soluble in alcohol (0.04 g/100 ml at 20°C) but soluble in water at 72.1 g/100 ml at 20°C.
Sr(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 240°C:
Sr(NO2)2 + O2 + heat0Sr(NO3)2
Strontium nitrite monohydrate, Sr(NO2)2·H2O, has the CAS number of 13470-06-9 and a molecular weight of 197.6464 g/mol. It occurs as yellow-white crystals which are hygroscopic. Its density is 2.84 g/ cm3. In air, the crystals begin to decompose at about 245 °C. It is soluble in water at about 58.5 g/100 ml at 20 °C.