Platinum – Production, Properties, Reactions and Uses
Platinum is a chemical element or silvery white, lustrous, malleable, high density metal in Periodic Table Group 10 with the symbol Pt and atomic number 78.
Under normal conditions, platinum metal is chemically inert to attack by mineral acids, air, or water. It has a higher ductility than gold, silver, or copper but is less malleable.
Platinum is a member of group 10 and a member of period 6 alongside elements such as ruthenium, rhodium, palladium, osmium, iridium, and platinum. All of these elements are extremely rare in the earth’s crust. It is also found alongside other noble metals such as copper, silver, and gold.
History of Platinum
In the seventh century, platinum was discovered in the tomb of Queen Shapenapit. In 1748, a Spanish expeditioner, Antonio de Ulloa maintained that a certain mineral contain metal with a very high melting point. It was known as Platina (little silver in Spanish)
A subsequent investigation by H Scheffer, Von Sickingen, and P Charbonneau developed the platinum metal isolation process and name.
Properties of Platinum
Atomic Number:
The atomic number of platinum is 78.
Electronic Configuration:
The electronic configuration for platinum is [Xe] 4f14 5d9 6s1.
Atomic Weight:
The atomic weight of this metal is 195.084.
Melting Point:
The melting point of Pt is 1768.3 °C.
Boiling Point:
The boiling point is 3825 °C.
Density:
The density of this metal is 21.45 g/cm3.
Molar Heat Capacity:
The molar heat capacity of platinum is 25.86 J mol−1 K−1.
Electrical Resistivity:
Electrical resistivity is 105 nΩ·m.
Crystal Structure: Face-centered cubic (fcc) crystal lattice
Platinum belong to group 10 of the periodic table and it also belongs to period 6.
This metal belongs to the d-block of the periodic table.
The oxidation numbers of Pt are +2, +4.
The electronegativity of Pt is 2.28 (Pauling scale)
Ionization Energy:
The first ionization energy of this metal is 870 kJ/mol while the second is 1791 kJ/mol.
The ionization energy of group-10 elements such as Ni, Pd, and Pt increases with increasing atomic number. Pd and Pt have the same atomic radius due to lanthanide construction.
The Position of Platinum in the Periodic Table
This metal is found in group 10 of the periodic table with d-block elements and transition metals. This metal’s electronic valence shell configuration is [Xe] 4f14 5d9 6s1.
It shares many similarities with palladium, another member of the group. Both +2 and +4 oxidation numbers or states are the most common.
Where can Platinum be Found?
South Africa, Canada, Russia, Brazil, Columbia, and other countries are the primary producers of platinum. It is extremely rare in the earth’s crust, occurring at about 0.01 ppm. The metal is commonly found with Cu, Ag, and Au sulfides and arsenides.
The most common platinum metal minerals are braggite (Pd, Pt, Ni)S, sperrylite (PtAs2), and copper (PtS).
Production of Platinum
Although Pt is most commonly found in placer deposits, platinum and platinum group metal (PGM) miners typically extract the metal from the platinum-containing ores sperrylite and copperite.
This metal is always found in conjunction with other PGMs. PGMs occur in sufficient quantities in South Africa’s Bushveld complex and a limited number of other ore bodies to make it economically viable to extract these metals exclusively; whereas platinum and other PGMs are extracted as by-products of nickel and copper in Russia’s Norilsk and Canada’s Sudbury deposits. Platinum extraction from ore is both capital and labor intensive. One troy ounce (31.135g) of pure platinum can take up to 6 months and 7 to 12 tons of ore to produce.
The First Step of Production
The first step in this process is to crush platinum-containing ore and immerse it in water containing reagents, a process known as ‘froth flotation.’ Air is pumped through the ore-water slurry during flotation. Pt particles bind to oxygen and rise to the surface as froth, which is skimmed off for further refining.
The Final Stages of Platinum Production
Even after drying, the concentrated powder contains less than 1% Pt. It is then heated in electric furnaces to over 2732F° (1500C°) and the air is blown through again to remove iron and sulfur impurities. Nickel, copper, and cobalt are extracted using electrolytic and chemical techniques, yielding a concentrate containing 15-20% PGMs.
Applications of Platinum Metal
- Platinum is commonly used as a chemical catalyst in a variety of chemical reactions.
- It is used in hydrocarbon reforming, ammonia oxidation to NO, and sulfur dioxide (SO2) oxidation to sulfur trioxide (SO3).
- Pt is also used to make laboratory equipment such as crucibles, boats, and so on.
- It is used in the manufacture of electrical apparatus and resistance wire.
- Pt electrodes are used in conductance and electrochemical cell measurements.
- It is currently primarily used in car exhaust converters to reduce pollution levels.
- Cis-Pt(NH3)2Cl2 (cisplatin) is an antitumor drug that is used in cancer chemotherapy. The use of Cis-Pt(NH3)2Cl2 in the treatment of solid tumors, particularly genito-urinary tumors, has been reported to have a very high success rate.
- A significant amount of this metal is used in the production of jewelry.
