Platinum (Pt) - Properties, Applications

Topics Covered

Introduction
Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Applications

Introduction

Platinum is a dense, malleable, ductile, precious, gray-white transition metal with an atomic number of 78. As a member of group 10 of the periodic table, platinum exhibits excellent corrosion resistance at elevated temperatures.

It is sometimes alloyed with iridium to form platiniridium. It is a very rare metal, occurring at a concentration of only 0.005 ppm in the Earth’s crust.

Platinum is more ductile than copper, silver and gold, and it does not oxidize at any temperature. It is insoluble in nitric and hydrochloric acid, but dissolves in hot aqueous solution to form chloroplatinic acid.

Chemical Properties

The chemical properties of platinum are provided in the table below.

Chemical Data
CAS number 6/4/7440
Thermal neutron cross section 9 barns/atom
Electrode potential 1.2 V
Ionic radius 0.650 Å
Electronegativity 2.2
X-ray absorption edge 0.1582 Å
Electrochemical equivalent 1.816 g/A/h

Physical Properties

The following table discusses the physical properties of platinum.

Properties Metric Imperial
Density 21.45 g/cm3 0.7749 lb/in3
Melting point 1769 °C 3216°F
Boiling point 3825°C 6917°F

Mechanical Properties

The mechanical properties of platinum are tabulated below.

Properties Metric Imperial
Tensile strength 125-165 MPa 18100-23900 psi
Modulus of elasticity 171 GPa 24800 ksi
Bulk modulus 230 GPa 33359 ksi
Shear modulus 62 GPa 8990 ksi
Poisson’s ratio 0.39 0.39
Elongation at break 35% 35%
Hardness, Vickers 40 40

Thermal Properties

The thermal properties of platinum are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20°C/68°F) 9.10 µm/m°C 5.06 µin/in°F
Thermal conductivity 69.1 W/mK 480 BTU in/hr.ft².°F

Applications

The most common use of platinum is as a catalyst in chemical reactions. It is used as a catalytic converter in automobiles, which allows for complete combustion of unburned hydrocarbons from the exhaust.

It is extensively used for jewelry, usually as a 90–95% alloy, due to its inertness and shine. It is manufactured into metal gauzes for producing nitric acid, and used as a catalyst to enhance fuel cell efficiency. Platinum-cobalt, an alloy of roughly three parts platinum and one part cobalt, is used to make relatively strong permanent magnets. Platinum-based anodes are employed in steel piers, pipelines and ships.

Other applications of platinum include:

  • Turbine engines
  • Spark plugs
  • Oxygen sensors
  • Anticancer drugs
  • Electrodes

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