Platinum

Last Updated: April 28, 2024

Platinum

On a captivating journey through the world of Platinum, a symbol of luxury and a cornerstone in various scientific fields. This comprehensive guide sheds light on the definition, meaning, and multifaceted uses of Platinum, from adorning the finest jewelry to driving innovations in medicine and technology. With its unique properties and compounds, Platinum stands out as a metal of unparalleled importance. Through vivid examples, this exploration uncovers the mysteries behind Platinum’s enduring value and its pivotal role in advancing modern science and industry. Discover the versatility and elegance of Platinum, a metal that continues to shape our world and inspire endless possibilities.

What is Platinum ?

Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes and is one of the rarer elements in the Earth’s crust. Platinum is known for its remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal.

Platinum Formula

  • Formula:Pt
  • Composition: Consists of a single platinum atom.
  • Bond Type: In its elemental form, platinum does not form bonds as it is a pure element. However, platinum can participate in covalent or ionic bonding when reacting with other elements. Platinum commonly forms coordination compounds where it acts as a transition metal capable of forming bonds with a variety of ligands.
  • Molecular Structure: As a pure element, platinum does not present a molecular structure in the traditional sense of compounds. In its bulk metallic form, platinum exhibits a face-centered cubic crystalline structure, which contributes to its high malleability and ductility.
  • Electron Sharing: In compounds, platinum typically shares electrons covalently, forming complexes with a variety of organic and inorganic ligands. Platinum’s most common oxidation states are +2 and +4, which play a significant role in its chemical reactivity and its ability to act as a catalyst.
  • Significance: Platinum’s significance lies in its broad range of industrial, chemical, and medicinal applications. Its exceptional resistance to corrosion and oxidation, along with its catalytic properties, make it invaluable in automotive catalytic converters, jewelry, electronics, and anticancer drugs.
  • Role in Chemistry: The role of platinum in chemistry is extensive and varied. It serves as a crucial catalyst in numerous chemical reactions, including those in the automotive, pharmaceutical, and petrochemical industries. Platinum compounds, especially cisplatin and its derivatives, are significant in chemotherapy treatments for cancer. The study of platinum and its compounds continues to provide valuable insights into catalysis, materials science, and medicinal chemistry, reflecting its importance beyond the elemental form

Atomic Structure of Platinum

Atomic Structure of Platinum

Platinum, in contrast to hydrogen, is a metallic element with distinctive characteristics that enable a wide range of applications, including remarkable stability in both solid and liquid forms. The behavior of platinum at the atomic and molecular levels significantly diverges from that of hydrogen, owing to its position as a transition metal in the periodic table and its distinct metallic characteristics.

Atomic Level: Each platinum atom (Pt) contains 78 protons in its nucleus and is expected to have 78 electrons orbiting around it. The electron configuration of platinum is [Xe] 4f¹⁴ 5d⁹ 6s¹, indicating a complex electron configuration that allows for various oxidation states, similar to other elements in group 10 of the periodic table. This contributes to its significant chemical reactivity and the ability to form a variety of compounds under standard conditions.

Molecular Formation: Unlike hydrogen, which forms simple molecules like H₂ through covalent bonding, platinum does not form molecules in the same manner due to its metallic nature. In bulk form, platinum atoms are organized in a face-centered cubic lattice structure. This structure is characterized by metallic bonding, where electrons are delocalized over many platinum atoms, differing fundamentally from the discrete electron sharing seen in hydrogen’s covalent bonds. Platinum’s metallic form is stable and can be observed directly, thanks to its resistance to corrosion and high melting point, making it valuable for industrial, jewelry, and catalytic applications

 Properties of Platinum 

_Properties of Platinum 

 Physical Properties of Platinum

Physical Property Description
Atomic Number 78
Atomic Mass 195.084 u
Density 21.45 g/cm³ at 20°C
Melting Point 1768.3°C
Boiling Point 3825°C
State at 20°C Solid
Color Silvery-white
Electrical Conductivity Good conductor of electricity

Chemical Properties of Platinum

Platinum is a transition metal with notable chemical stability and catalytic properties. Its electron configuration is [Xe] 4f¹⁴ 5d⁹ 6s¹, which contributes to its versatility in forming compounds, primarily in the +2 and +4 oxidation states.

  1. Reaction with Oxygen:
    • Platinum is resistant to oxidation and does not tarnish at room temperature.
    • Equation: Pt(s) + O(g) → No reaction under normal conditions.
  2. Reaction with Acids:
    • Platinum is highly resistant to corrosion and does not dissolve in most acids.
    • Equation: Pt(s) + HCl(aq) → No reaction.
  3. Reaction with Aqua Regia:
    • Platinum dissolves in aqua regia to form chloroplatinic acid (HPtCl).
    • Equation: Pt(s) + 4HNO(aq) + 6HCl(aq) → HPtCl(aq) + 4NO(g) + 4HO(l).
  4. Catalytic Properties:
    • Platinum is an excellent catalyst for the hydrogenation of alkenes and alkynes, and for the reduction of vehicle emissions.
    • Catalytic Example: CH(g) + H(g) → CH(g) (in the presence of Pt catalyst)

Thermodynamic Properties of Platinum

Thermodynamic Property Description
Heat of Fusion 22.17 kJ/mol
Heat of Vaporization 510 kJ/mol
Specific Heat Capacity 25.86 J/(mol·K) at 25°C
Thermal Conductivity 71.6 W/(m·K)
Thermal Expansion 8.8 µm/(m·K) at 25°C

Material Properties of Platinum

Material Property Description
Hardness 3.5 – 4 (Mohs scale)
Tensile Strength 125 – 240 MPa
Malleability High; can be beaten into thin sheets
Ductility High; can be drawn into fine wire
Elastic Modulus 168 GPa
Poisson’s Ratio Approximately 0.38

Electromagnetic Properties of Platinum

Property Value
Electrical Conductivity Good conductor, approximately 9.4 × 10^6 S/m
Magnetic Susceptibility Paramagnetic at room temperature
Thermal Conductivity 71.6 W/(m·K) at 25 °C
Electrical Resistivity 10.6 nΩ·m at 20 °C
Reflectivity Relatively high, especially for infrared light
Permeability Slightly greater than 1 (paramagnetic)

Nuclear Properties of Platinum

Property Value
Atomic Number 78
Atomic Mass 195.084 u
Isotopes Natural platinum consists of 5 stable isotopes: Pt-190, Pt-192, Pt-194, Pt-195, Pt-196, and Pt-198
Radioisotopes Pt-193 with a half-life of 50 years; others with shorter half-lives
Neutron Cross Section Pt-195 has a high neutron absorption cross-section, important in nuclear reactors
Stable Isotope Natural Abundance Varies, with Pt-195 being the most abundant at approximately 33.83%
Neutron Number for Stable Isotopes Ranges from 112 to 116 for the stable isotopes
Fissionability Not fissionable, but used as a neutron reflector in some nuclear reactor designs

Preparation of Platinum

The preparation of platinum typically involves complex processes to extract and refine the metal from its ores. Platinum is often found naturally alloyed with small amounts of other platinum-group metals, including palladium, rhodium, osmium, iridium, and ruthenium. Here’s a general overview of how platinum is prepared:

  1. Ore Extraction: Platinum ores, such as sperrylite (platinum arsenide, PtAs2) and cooperite (platinum sulfide, PtS), are mined from the Earth.
  2. Crushing and Grinding: The ore is crushed and ground to liberate platinum particles from the surrounding rock.
  3. Froth Flotation: The ground ore is mixed with water to form a slurry. Chemical reagents are added, and air is blown through the mixture, creating froth. Platinum particles attach to the bubbles and are collected.
  4. Smelting: The concentrated ore is then smelted in a furnace, where high temperatures remove sulfur and other impurities, leaving a matte containing the platinum metals.
  5. Chemical Refining: The matte undergoes various chemical processes, including leaching with aqua regia (a mixture of hydrochloric and nitric acids) to dissolve the platinum metals.
  6. Precipitation and Purification: Platinum is precipitated from solution, typically as ammonium chloroplatinate. Further refining, often through additional dissolution and precipitation steps, purifies the platinum.
  7. Final Reduction: The purified compound is finally heated to high temperatures to decompose it, leaving behind pure platinum metal.

Chemical Compounds of Platinum

Chemical Compounds of Platinum

  1. Platinum(II) Chloride (PtCl)
    • Preparation Equation: Pt + Cl→ PtCl
    • Properties: Platinum(II) chloride is used as a starting material for synthesizing other platinum compounds and in catalysis.
  2. Platinum(IV) Chloride (PtCl)
    • Preparation Equation: Pt + 2Cl → PtCl
    • Properties: It is used in the preparation of platinum-based catalysts and as a precursor for many other platinum compounds.
  3. Cisplatin ([PtCl(NH3)])
    • Preparation Equation: PtCl + 2NH → [PtCl(NH)] + 2HCl
    • Properties: Cisplatin is a chemotherapy drug used to treat various types of cancer. It works by interfering with DNA replication in cancer cells.
  4. Tetraammine platinum(II) Chloride ([Pt(NH)]Cl)
    • Preparation Equation: PtCl + 4NH → [Pt(NH)]Cl
    • Properties: This compound serves as an intermediate in the synthesis of other platinum compounds and complexes
  5. Platinum(II) Iodide (PtI)
    • Preparation Equation: Pt + I → PtI
    • Properties: Platinum(II) iodide is used in research contexts for its potential applications in organic synthesis and as a catalyst. Like other platinum halides, it serves as a precursor to various platinum complexes, demonstrating platinum’s versatile bonding capabilities.
  6. Potassium Hexachloroplatinate(IV) (K[PtCl])
    • Preparation Equation: PtCl + 2KCl → K[PtCl]
    • Properties: This salt is significant in the recovery and purification of platinum from its ores and as an intermediate in the synthesis of other platinum compounds. Its stability and solubility in water make it useful in the electroplating process and in the preparation of catalysts and other platinum-based reagents.

Isotopes of Platinum

Isotope Natural Abundance (%) Half-life Decay Mode Notes
Pt-190 0.014 6.5×10^11 years Alpha decay Used in scientific research
Pt-192 0.782 Stable N/A
Pt-194 32.967 Stable N/A
Pt-195 33.832 Stable N/A
Pt-196 25.242 Stable N/A
Pt-198 7.163 Stable N/A
Pt-191 Trace 2.96 days Beta decay Used in research, no commercial application
Pt-193 Trace 50 years Beta decay Potential use in nuclear medicine

Uses of Platinum

Uses of Platinum

  1. Catalytic Converters: Platinum is a key component in catalytic converters, reducing harmful emissions from vehicles by catalyzing the oxidation of CO and hydrocarbons to CO2 and water, and the reduction of NOx to nitrogen.
  2. Jewelry: Platinum’s resistance to wear and tarnish, along with its prestigious status, makes it a preferred metal for fine jewelry.
  3. Chemical Catalysts: It is used as a catalyst in the chemical industry, including for the production of silicone and other chemicals.
  4. Fuel Cells: Platinum serves as an effective catalyst in the electrodes of hydrogen fuel cells, converting hydrogen into electricity.
  5. Medical Devices: Platinum’s biocompatibility makes it suitable for use in medical devices, such as pacemakers and implantable defibrillators.
  6. Cancer Treatment: Platinum-based drugs, such as cisplatin, are used in chemotherapy to treat various types of cancer.
  7. Electronics: Due to its excellent conductivity and stability, platinum is used in electrical contacts, wires, and other electronic components.
  8. Investment: Platinum is considered a valuable investment, with platinum bars, coins, and investment funds available to investors

Production of Platinum

Platinum production involves several key steps, from mining to the final purification of the metal. The process begins with the extraction of platinum-bearing ore and ends with the production of pure platinum metal suitable for commercial use.

  1. Mining: Platinum is extracted from platinum-bearing ores such as sperrylite (platinum arsenide) and cooperite (platinum sulfide), often found mixed with other platinum group metals (PGMs).
  2. Concentration: The ore is crushed and milled to break it down into smaller particles. Froth flotation is then used to separate platinum from other minerals in the ore.
  3. Smelting: The concentrated ore is smelted in a furnace, where high temperatures remove impurities as slag and produce a matte containing PGMs.
  4. Refining: The matte undergoes various refining processes to extract individual metals. This often involves complex chemical treatments, including dissolution in aqua regia, precipitation, and solvent extraction techniques.
  5. Electrolytic and Chemical Refining: To achieve high purity, platinum is subjected to further electrolytic refining or chemical processes, which remove any remaining impurities.
  6. Final Product: The result is pure platinum, which is then formed into bars, ingots, or powder, depending on its intended use

Applications of Platinum

Platinum is a versatile metal with a wide range of applications across various industries due to its unique properties, such as excellent corrosion resistance, good thermal and electrical conductivity, and remarkable catalytic abilities.

  1. Catalytic Converters: Platinum is used as a catalyst in catalytic converters for cars, reducing harmful emissions by converting them into less harmful substances.
  2. Jewelry: Due to its lustrous appearance and resistance to tarnishing, platinum is highly valued in fine jewelry, often used for rings, bracelets, and necklaces.
  3. Chemical Industry: Platinum’s catalytic properties make it valuable in the chemical industry for processes such as the production of nitric acid, silicone, and benzene.
  4. Fuel Cells: Platinum serves as an efficient catalyst in hydrogen fuel cells, which convert hydrogen and oxygen into water, producing electricity in the process.
  5. Medicine: Platinum compounds, especially cisplatin, are used in chemotherapy to treat various types of cancer due to their ability to damage the DNA of cancer cells.
  6. Electronics: Platinum is used in computer hard drives, fiber optic cables, and thermocouples due to its stability and conductivity.

Platinum is a highly valued, versatile element with remarkable physical and chemical properties, including its catalytic efficiency, resistance to corrosion, and electrical conductivity. It plays a critical role in various industries, from automotive to medical, and continues to be a symbol of prestige in jewelry. Understanding platinum’s isotopes further enriches our appreciation for this rare and precious metal

 

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Chemical Compounds of Platinum

Isotopes of Platinum

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