Lithium SticksCAS #: 7439-93-2

Synonyms 

Lithium sticks, laboratory grade, 2.5 g for synthesis, protective liquid: paraffin oil

Molecular Weight: 6.941 

Appearance: Silvery sticks immersed in heavy mineral (paraffin) oil 

Melting Point: 180 °C 

Boiling Point: 1347 °C 

Density: 0.534 g/cm3 

Solubility in H2O: Reacts violently 

Poisson's Ratio: N/A 

Young's Modulus: 4.9 

GPa Vickers Hardness: N/A 

Tensile Strength: N/A 

Thermal Conductivity: 0.848 W/cm/K @ 298-C.2 K 

Thermal Expansion: (25 °C) 46 µm·m-1·K-1 

Electrical Resistivity: 8.55 microhm-cm @ 0 °C 

Electronegativity: 1.0 

Paulings Specific Heat: 0.85 Cal/g/K @ 25 °C 

Heat of Fusion: 1.10 Cal/gm mole 

Heat of Vaporization: 32.48 K-Cal/gm atom at 1342 °C

Product Introduction: Potassium Metal (K, CAS #: 7439-93-2)

Potassium metal, denoted by the chemical symbol K and CAS number 7439-93-2, is an alkali metal renowned for its exceptional reactivity and pivotal role in industrial chemistry. As a Group 1 element, this soft, silvery-white metal exhibits properties that make it both a valuable reagent and a material requiring careful handling. Its low density, high chemical activity, and ability to form diverse compounds position it as a cornerstone in sectors ranging from metallurgy to energy research, despite its inability to be used in unprocessed form in consumer applications.

Defining Chemical & Physical Traits

Potassium’s behavior is shaped by its distinctive properties:

Mechanical Characteristics: Exceptionally soft (Mohs hardness: 0.4), allowing it to be sliced with a knife. Freshly cut surfaces reveal a bright metallic luster that dulls within seconds due to reaction with atmospheric oxygen.

Thermal Properties: Boasts a low melting point (63.5°C) and a boiling point of 759°C, enabling its use in high-temperature systems when alloyed. Its density of 0.862 g/cm³ at 20°C means it floats on water, a trait that amplifies its reactive hazards.

Chemical Reactivity: Exhibits one of the most vigorous reactions with water among alkali metals, producing potassium hydroxide (KOH) and hydrogen gas (H₂) with sufficient heat to ignite the hydrogen (flame temperature ~1,900°C). It reacts with oxygen to form a complex oxide layer (K₂O, K₂O₂, KO₂) and with halogens to create ionic salts (e.g., KCl, KBr) with high melting points.

Electrical Conductivity: Conducts electricity at ~14.0 × 10⁶ S/m, comparable to other alkali metals, due to its delocalized electron structure.

Specialized Applications Across Industries

Potassium metal’s utility lies in its role as a reactive precursor and reducing agent:

Fine Chemical Synthesis

In organic chemistry, it initiates carbon-carbon bond-forming reactions like the Wurtz coupling, where it promotes dimerization of alkyl halides (e.g., 2R-X + 2K → R-R + 2K-X). It also serves as a strong base in deprotonation reactions, enabling the synthesis of pharmaceuticals and agrochemicals. Its ability to react with alcohols (forming alkoxides) makes it useful for preparing specialty esters.

Advanced Metallurgy

As a reducing agent, it extracts high-purity metals from their oxides, such as titanium (Ti) from TiO₂: TiO₂ + 4K → Ti + 2K₂O. This method produces metals with <0.1% impurities, critical for aerospace components and medical implants. It also refines zirconium and hafnium, which are used in nuclear reactors for their neutron-absorbing properties.

Heat Transfer & Nuclear Systems

Sodium-potassium alloys (NaK) with 40–78% potassium melt as low as -12.6°C, remaining liquid up to 785°C. These alloys transfer heat in fast-neutron reactors and industrial furnaces, outperforming water or oil in high-temperature (300–500°C) environments due to their low vapor pressure and high thermal conductivity (~25 W/m·K).

Battery Research

While not used directly in commercial batteries, potassium metal is studied as an anode in next-generation potassium-ion batteries (PIBs). Its high theoretical capacity (687 mAh/g) and abundance make it a potential low-cost alternative to lithium, though dendrite formation remains a challenge.

Laboratory & Calibration

Serves as a standard for atomic absorption spectroscopy (AAS) and mass spectrometry (MS), ensuring accurate measurement of potassium in biological and environmental samples. It is also used to generate hydrogen gas for small-scale reactions.

Comparison with Other Alkali Metals

Potassium offers unique advantages over lithium, sodium, and cesium:

vs. Sodium: More reactive, enabling reduction of metals that sodium cannot (e.g., hafnium). NaK alloys with potassium have lower melting points than pure sodium, expanding their thermal range.

vs. Lithium: Less dense and more abundant, making it preferable for large-scale industrial processes. However, lithium’s lower reactivity simplifies handling in battery applications.

vs. Cesium: Far more cost-effective (cesium costs ~\(10,000/kg vs. potassium’s ~\)50/kg) while retaining sufficient reactivity for most reducing applications.

Key Limitation: Higher reactivity than sodium increases handling risks, requiring more stringent safety protocols.

Production & Purity Standards

Industrial synthesis of potassium metal relies on electrolysis due to its high reduction potential:

Electrolysis of Molten KCl: A Downs cell-like setup with a graphite anode and iron cathode electrolyzes KCl at 770°C. Chlorine gas (Cl₂) is released at the anode, while molten potassium collects at the cathode, floating to the surface for extraction.

Purification: Distillation under reduced pressure (1–10 mmHg) at 300–400°C separates potassium from sodium impurities, achieving 99.9% purity.

Quality control includes:

Glow discharge mass spectrometry (GDMS) to detect trace metals (Na <500 ppm, Ca <100 ppm).

Gas chromatography (GC) to measure hydrogen and oxygen content (<0.1%).

Critical Safety Protocols

Potassium’s reactivity demands extreme caution:

Storage: Must be submerged in dry mineral oil or argon-purged containers. Glass ampoules are used for small quantities to prevent punctures.

Handling: Requires a Class IIB fume hood, flame-resistant clothing, and face shields. Tools must be non-sparking (brass or Teflon) to avoid igniting hydrogen.

Emergency Response: Water must never be used on fires—Class D extinguishers (graphite, sand) or dry soda ash (Na₂CO₃) are required. Skin contact requires immediate removal of contaminated clothing and flushing with mineral oil (not water) to prevent further reaction.

Disposal: Controlled reaction with isopropanol (2K + 2C₃H₇OH → 2KC₃H₇O + H₂) neutralizes excess potassium, with waste solutions treated as hazardous.

Packaging & Sourcing

Available in forms tailored to industrial and research needs:

Ingots: 10g–1kg in oil-filled steel cans; 5–50kg in sealed drums for metallurgical use.

Shavings/Powder: 100g–5kg in argon-sealed bags for chemical synthesis.

NaK Alloys: 1–20L sealed containers with pressure relief valves, available in 50/50 or 78/22 K/Na ratios.

High-purity (99.99%) grades are available for semiconductor and research applications, with certificate of analysis (CoA) provided.

For technical data, safety training, or bulk inquiries, contact our team specializing in reactive metals and alkali metal alloys.

Health & Safety Information

 Signal Word: Danger 

Hazard Statements: H260-H314 

Hazard Codes: F, C 

Precautionary Statements: P223-P231 + P232-P280-P305 + P351 + P338-P370 + P378-P422 

Flash Point: 871 °C 

Risk Codes: 14/15-34 

Safety Statements: 8-43-45 

RTECS Number: OJ5540000 

Transport Information: UN 1415 4.3/PG 1 

WGK Germany: 2 

GHS Pictogram: Image,Image

Chemical Identifiers

 Linear Formula: Li 

Pubchem CID: 3028194 

MDL Number: MFCD00134051 

EC No.: 231-102-5 

Beilstein/Reaxys No.: N/A 

SMILES: [Li] 

InchI Identifier: InChI=1S/Li 

InchI Key: WHXSMMKQMYFTQS-UHFFFAOYSA-N

Packing of Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 735 gallon liquid totes Special package is available on request.