Strontium Nitrate, Sr(NO₃)₂

Strontium Nitrate, Sr(NO₃)₂, may be obtained by dissolving strontium hydroxide or carbonate in nitric acid and crystallising from the hot solution. It is prepared technically by precipitation from concentrated solutions of strontium chloride and sodium nitrate. It forms octahedra or cubic octahedra isodimorphous with strontium chlorate and of density 2.98 at 16.8° C. Its melting-point is 645° C. With potassium and sodium nitrates it forms a ternary eutectic mixture of melting-point 208.4° C., consisting of 9 equivalents of strontium, 50 of potassium, and 41 of sodium.

From a cold saturated solution the tetrahydrate, Sr(NO₃)₂.4H₂O, separates out in monoclinic prisms of density 2.11 – 2.25. These melt in their water of crystallisation, which is readily lost at 100° C. It has also been stated that a dihydrate separates from cold solutions. It is probable that the transition temperature from the tetrahydrate to the anhydrous form is between 30° and 40° C., because at 32° C. both forms have been obtained by crystallisation from solution. The heat of solution of the anhydrous salt is 4.62 Cal., and of the hydrated -3.05 Cal. The heat of hydration is 7.68 Cal.

The following values for the solubility of strontium nitrate are compiled from various data: -

Temperature, ° C.	-6	0	10	20	30	40	60	80	100	108
Parts Sr(NO3)2 in 100 parts water.	32.5	39.5	59.0	68.0	87.6	91.3	94.0	97.2	101	103

The densities and boiling-points, the coefficients of expansion, the freezing-points, the viscosities, the refractive indices, and the equivalent conductivities of solutions of different concentrations have been studied.

Strontium nitrate is not very soluble in alcohol, one part dissolving in 8500 of alcohol. No compound is formed. The tetrahydrate is in equilibrium with solutions in dilute alcohol, but the anhydrous salt with solutions in concentrated alcohol.

Strontium nitrate dissolves to a considerable extent in liquid ammonia in which it is a good electrolyte.

The solubilities of strontium nitrate and hydroxide in presence of each other have been studied at 25° C., but no basic salts have been isolated.

Strontium nitrate is used in pyrotechnics for the production of red light.