Strontium iodide, also called strontium diiodide, is a salt containing strontium and iodine ^{[1, 2]}. Being a water-soluble, deliquescent compound, it absorbs moisture from the atmosphere and becomes physically changed slightly ^[2]. It produces strontium oxide and iodine when heated at high temperatures in the presence of air ^[2].

Identification

CAS Number: 10476-86-5 ^{[2, 3]}

PubChem CID: 25304 ^{[1, 2]}

ChemSpider ID: 23637 ^[3]

EC Number: 233-972-1 ^{[2, 3]}

RTECS Number: WK9275000 ^{[2, 4]}

Formula

The molecular formula of its anhydrous form is I₂Sr ^[1], while the linear formula is SrI₂ ^[4]. Its hexahydrate form has the chemical formula SrI₂.6H₂O ^[2].

Structure

Strontium iodide has an orthorhombic crystal structure ^[2].

Properties

Here we share some common physical properties of this ionic compound.

Appearance

It appears as a colorless or white crystalline solid ^{[2, 4]}

Odor

Strontium iodide is odorless ^[5].

Molar Mass

The mass of one mole of strontium iodide is 341.43 g/mol ^{[1, 2, 4]}

Melting Point

The compound melts at a temperature of 507-645 °C (780-918 K, 945-1193 °F) ^{[2, 4]}

Boiling Point

It boils at a temperature of 1773 °C (2046 K, 3223 °F) ^{[2, 4]}.

Density

The density of its anhydrous form is 4.55 g/cm^3, and its hexahydrate form is 4.40 g/cm^{3 [2, 4]}.

Solubility

It is highly soluble in water at room temperature and sparingly soluble in ethanol, with a solubility value of 177 g/100 ml at 20 °C and 3.1 g/100 ml at 4 °C, respectively ^[2].

How to make Strontium Iodide

Its preparation involves the reaction of strontium carbonate (SrCO₃) with hydroiodic acid (HI) ^[2].

SrCO₃ + 2HI → SrI₂ + H₂O + CO₂

The strontium iodide produced can be easily identified because it becomes yellow upon exposure to air ^[2].

Chemical Reactions with Other Compounds

Lithium Sulfide and Strontium Iodide

When SrI₂ reacts with Li₂S, the compounds undergo a double displacement reaction to form SrS and LiI ^[6]. The chemical equation is given below:

Li₂S + SrI₂ → 2LiI + SrS

Potassium Sulfate and Strontium Iodide

The precipitation reaction involving potassium sulfate and strontium iodide is given below:

K₂SO₄ + SrI₂ → 2KI + SrSO₄

Uses

• Because of its high density, atomic number, scintillation light yield, and optical clarity, Europium-doped SrI₂ is used as a scintillator for detecting gamma radiation ^[2].
• Anhydrous strontium iodide is used as a replacement for potassium iodide in medicines ^[2].
• Large-diameter strontium iodide crystals are now commercially grown with the vertical Bridgman technique ^{[2, 7]}.

Health and Safety Information

Although the toxicological properties of SrI₂ have not been extensively studied, compounds of strontium are known to be slightly toxic ^[5]. Prolonged exposure through inhalation may cause headaches, tight chest, nose and respiratory system irritation, and lacrimation ^[5]. If ingested, it may cause gastric irritation, diarrhea, abdominal pain, and burns to the mouth ^[5]. Moreover, it may act as a strong irritant to the eye and skin, causing redness, black spots, boils, pimples, blisters, and hives ^[5].

First Aid Measures

If a victim has been exposed to large amounts of strontium iodide, the following measures should be taken:

Ingestion: Seek medical attention immediately and avoid inducing vomiting ^[5].

Inhalation: Remove the affected person to fresh air and keep him warm ^[5]. The victim should be immediately taken to a medical practitioner ^[5].

Eyes: Flush the victim’s eyes with lukewarm water for more than 15 minutes and seek emergency medical treatment ^[5].

Skin: After removing the contaminated clothes, brush the material off the skin and wash the affected area using mild soap and water ^[5]. Quickly take the person to a doctor to avoid acute irritation ^[5].

Safety Measures

For breathing protection, a NIOSH-approved respirator should be worn ^[5]. The compound should be kept in an inert gas and dry box to avoid contact with moisture ^[5]. Other protective equipments like an apron, lab coat, impervious gloves, and safety goggles are required for the safety of the skin and eyes ^[5].

Strontium Iodide Availability

Hangzhou Dayangchem Co. Ltd., IBIS Chemie International, Amadis Chemical Co. Ltd., Chemos GmbH & Co. KG, and Santa Cruz Biotechnology Inc. are some of the renowned suppliers of SrI₂ globally ^[9].