Нитрат стронция

Описание

Strontium nitrate has the molecular formula of Sr(NO3)2 and the molecular weight of 211.6327 g/mol. Strontium nitrate is prepared by treating strontium carbonate with nitric acid. The solution is evaporated and crystallized:
SrCO3 +HNO3 ? Sr(NO3)2 + CO2 +H2O
Crystallization yields the tetrahydrate, Sr(NO3)2· 4H2O, which, on heating, melts at 31.3 °C in its own waters of hydration and then decomposes >100 °C to form the anhydrous nitrate. The anhydrate melts at 570 °C (It begins to decompose as low as 545 °C), is soluble in water (70.3 gm/100 ml at 20 °C) and is very slightly soluble in ethanol. These colorless crystals, or white powder, have a density of 2.986 g/cm³ and its CAS number is 10042-76-9. It is very soluble in water, as shown in Table 4.11 on the following page. Strontium nitrate apparently forms only the tetrahydrate when a solution is evaporated below 80°C. Otherwise it decomposes at higher solution temperatures to Sr(OH)2 and nitrogen oxides. The nitric acid concentration makes little difference in the hydrate produced, in contrast to other alkaline earths like Ca and Mg.

Химические свойства

Strontium nitrate is a white crystalline solid

Физические свойства

Colorless cubic crystals or white powder or granules; density 2.986 g/cm³; melts at 570°C; very soluble in water, 80 g/100 mL at 18°C; very slightly soluble in ethanol.
The tetrahydrate constitutes colorless monoclinic crystals; density 2.20 g/cm³; loses all water of crystallization at 100°C; converts to strontium oxide, SrO at 1,100°C; very soluble in water, 60.4g/100 mL at 0°C, 206 g/100 mL at 100°C; soluble in liquid ammonia; very slightly soluble in ethanol and acetone.

Использование

Strontium nitrate is used in pyrotechnics, for producing marine and railroad signals, and in matches.

Подготовка

Strontium nitrate is prepared by treating strontium carbonate with nitric acid. The solution is evaporated and crystallized:
SrCO3 + HNO3 → Sr(NO3)2 + CO2 + H2O
Crystallization yields the tetrahydrate, Sr(NO3)2•4H2O, which on heating dehydrates to form the anhydrous nitrate.

Общее описание

A white crystalline solid. Noncombustible but accelerates burning of combustible materials. May explode if large quantities are involved in a fire or the combustible material is finely divided. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in pyrotechnics, in medicine, and to make other chemicals.

Реакции воздуха и воды

Soluble in water.

Профиль реактивности

Mixtures of metal/nonmetal nitrates with alkyl esters may explode, owing to the formation of alkyl nitrates; mixtures a nitrate with phosphorus, tin (II) chloride, or other reducing agents may react explosively [Bretherick 1979 p. 108-109]. Special Hazards of Combustion Products: Yields toxic gaseous oxides of nitrogen when involved in fire.

Угроза здоровью

Dust is irritating to skin, eyes, and respiratory system.

Профиль безопасности

Moderately toxic by ingestion and intraperitoneal routes. A powerful oxidizer. When heated to decomposition it emits toxic fumes of NOx.See also NITRATES and STRONTIUM COMPOUNDS.

Возможный контакт

Strontium nitrate is used in matches, pyrotechnics, marine signals; and railroad flares.

Перевозки

UN1507 Strontium nitrate, Hazard Class: 5.1; Labels: 5.1-Oxidizer.

Методы очистки

Crystallise it from hot water (0.5mL/g) by cooling to 0o.

Несовместимости

A strong oxidizer. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Violent reaction with reducing agents; combustibles, organics, or other readily oxidizable materials. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.