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%.
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/cm
3
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.
