Jul 29 2013
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:
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Turbine engines
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Spark plugs
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Oxygen sensors
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Anticancer drugs
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Electrodes