Barium nitrate (Ba(NO₃)₂: Structure, Properties & Uses

Barium nitrate (Ba(NO₃)₂) is an inorganic compound composed of barium, nitrogen, and oxygen. It is a white crystalline solid that is soluble in water and has a density of 2.65 g/cm³. Barium nitrate burns with a green flame. It is used in the production of fireworks, flares, and other pyrotechnic devices, as well as in the manufacture of glass and ceramics. It is also used as a reagent in chemical reactions.

Barium nitrate is toxic and requires careful handling. It should only be handled in a well-ventilated area with proper personal protective equipment (PPE) like gloves, safety glasses, and a dust mask to avoid inhalation or ingestion. Due to its oxidizing properties, it should be stored away from flammable materials.

Structure of Barium nitrate (Ba(NO₃)₂)

Barium nitrate (Ba(NO₃)₂) is an ionic compound composed of barium cations (Ba²⁺) and nitrate anions (NO₃⁻). It forms from the attraction between positively charged ions (cations) and negatively charged ions (anions).

Barium nitrate consists of one barium ion (Ba²⁺) and two nitrate ions (NO₃⁻) per formula unit. The nitrate ion (NO₃⁻) has a specific structure. It has a central nitrogen atom bonded to three oxygen atoms in a trigonal planar fashion. Each oxygen atom has a single bond with the nitrogen atom, and one oxygen also has a double bond with the nitrogen.

Crystal Structure

Barium nitrate crystals have a cubic crystal structure. This means the unit cell, the basic repeating unit of the crystal, is a cube where all sides are equal length and all angles are 90 degrees. Within this unit cell, the barium ions (Ba²⁺) are arranged in a specific pattern with each barium ion surrounded by 12 nitrate ions (NO₃⁻) from neighboring unit cells.

These surrounding nitrate ions are not perfectly aligned but rather form a distorted octahedron shape around the barium ion.

Preparation of Barium nitrate (Ba(NO₃)₂

One common method involves reacting barium carbonate (BaCO₃) with nitric acid (HNO₃). The reaction produces barium nitrate, water, and carbon dioxide as follows:

BaCO₃ + 2HNO₃ → Ba(NO₃)₂ + H₂O + CO₂

Alternatively, barium hydroxide (Ba(OH)₂) can be reacted with nitric acid to yield barium nitrate and water:

Ba(OH)₂ + 2HNO₃ → Ba(NO₃)₂ + 2H₂O

In a third method, barium sulfide (BaS) reacts with nitric acid to produce barium nitrate and hydrogen sulfide:

BaS + 2HNO₃ → Ba(NO₃)₂ + H₂S

The resulting barium nitrate solution can then be filtered to remove any impurities and evaporated to obtain the solid form of the compound. The preparation of barium nitrate should be carried out with caution, as barium compounds are toxic and nitric acid is corrosive.

Physical Properties of Barium nitrate (Ba(NO₃)₂

  • Appearance: White crystalline solid
  • Molecular Weight: 261.34 g/mol
  • Density: 3.24 g/cm³
  • Melting Point: 592 °C (1098 °F)
  • Boiling Point: Decomposes before boiling
  • Crystal Structure: Orthorhombic
  • Odor: Odorless
  • Refractive Index: 1.572
  • Thermal Stability: Decomposes upon heating, releasing oxygen and nitrogen dioxide

Chemical Properties of Barium nitrate (Ba(NO₃)₂

  • Chemical Formula: Ba(NO₃)₂
  • Oxidizing Agent: Acts as a strong oxidizer, supporting combustion and enhancing the intensity of flames.
  • Reactivity with Acids: Reacts with sulfuric acid (H₂SO₄) to produce barium sulfate (BaSO₄) and nitric acid (HNO₃): Ba(NO3​)2​(aq)+H2​SO4​(aq)→BaSO4​(s)+2HNO3​(aq)
  • Decomposition: Decomposes upon heating to release oxygen (O₂), nitrogen dioxide (NO₂), and barium oxide (BaO): 2Ba(NO3​)2​→2BaO+4NO2​+O2​
  • Reactivity with Reducing Agents: Reacts with reducing agents, potentially causing explosive reactions due to the release of gases.
  • Solubility: Highly soluble in water, leading to the formation of barium and nitrate ions: Ba(NO3​)2​→Ba2++2NO3−​
  • Reaction with Alkali Metals: Reacts with alkali metals to form barium compounds and release nitrogen oxides.

Uses of Barium nitrate (Ba(NO₃)₂

  • Pyrotechnics: It is used in fireworks to create green colors.
  • Glass and ceramics: It is used in the manufacturing of high-quality, low thermal expansion glass products.
  • Medical imaging: It is used as a contrast agent in medical radiology.
  • Oil and gas drilling: It is used in drilling fluids.
  • Electronics and optics: It is used in the manufacturing of barium titanate, which is employed in electronics for its dielectric properties.
  • Military applications: It was a primary ingredient in the “SR 365” incendiary charge used by the British in the De Wilde incendiary ammunition during World War II.
  • Vacuum tube industry: It is used in the manufacturing of vacuum tubes.
  • Tracer bullets: It is used to produce tracer bullets.
  • Signal flares: It is used in signal flares in the field.

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