Barium Nitrate, Ba(NO₃)₂

Barium Nitrate, Ba(NO₃)₂, has been found in the natural state in the Chili saltpetre beds. It may be obtained by neutralising nitric acid with barium hydroxide or carbonate. Owing to its slight solubility as compared with the other alkaline earth nitrates, it is precipitated in the cold by the action of sodium nitrate solution on a concentrated solution of barium chloride, or of sodium nitrate on barium sulphide. It may also be obtained by fusing barium sulphate with excess of calcium nitrate.

The salt, as ordinarily obtained, is anhydrous. It crystallises in colourless cubical octahedra and is isomorphous with the chlorate and bromate. The density is 3.22 and melting-point 595.5° C. By crystallising between 0° C. and 12° C. it may be obtained as the dihydrate. When heated strongly, barium nitrate is decomposed, giving barium oxide Or peroxide, oxides of nitrogen, and oxygen. Hydrogen reduces it at red heat with the formation of barium hydroxide.

The heat of solution of barium nitrate is -9.4 Cal. It is not remarkably soluble in water. The following values have been found for the composition of solutions at different temperatures: -

Temperature, °C	0.4	2.1	6	11	18	28.5	52	73	110	134	150	171	215
Grams Ba(NO3)2 per 100 grams solution	4.3	4.9	5.6	6.4	7.7	9.7	14.9	19.4	27.4	32.5	34.9	38.3	45.8

The solubility is diminished by the presence of barium chloride, potassium nitrate, and nitric acid. It is increased by barium hydroxide, but no basic nitrates are formed. The salt is practically insoluble in alcohol and in most organic solvents.

Aqueous solutions of barium nitrate have been studied from the point of view of density, boiling-point, freezing-point lowering in dilute solutions, viscosity, and electrical conductivity.

With potassium and sodium nitrates, barium nitrate forms a ternary eutectic mixture at 214.1° C.

A double salt is formed with barium acetate, Ba(NO₃)(CH₃COO).4H₂O, and one with potassium nitrate, Ba(NO₃)₂.2KNO₃, and Ba(NO₃)₂.2KNO₃.H₂O.