Difference Between Palladium and Platinum

Main Difference – Palladium vs Platinum

Palladium and platinum are often confusing because of their similar appearances. Both are shiny silvery-white metals. These metals are in the platinum group metals (PGM) which include palladium, rhodium, ruthenium, osmium, iridium, and platinum. Both palladium and platinum are transition metals and have the same electronegativity. But their chemical properties are different from each other. The main difference between palladium and platinum is that palladium has the least density and melting point among PGM elements whereas platinum has a considerably high density and a high melting point.

Key Areas Covered

1. What is Palladium
     – Definition, Chemical Properties, Uses
2. What is Platinum
     – Definition, Chemical Properties, Uses
3. What is the Difference Between Palladium and Platinum
     – Comparison of Key Differences

Key Terms: Acids, Atomic Number, Aqua Regia, Corrosion Resistance, Density, Melting Point, Palladium, Platinum, Platinum Group Metals

What is Palladium

Palladium is a chemical element with the symbol Pd and atomic number 46. It is a shiny silvery-white metal. At room temperature and pressure, it is in the solid phase. Palladium is resistant to corrosion from air and acids at ordinary temperatures.

Chemical Properties of Palladium

Some chemical properties of Palladium are given below.

• Atomic number – 46
• Atomic mass – 106.42 g/mol
• Electron configuration – [Kr] 4d¹⁰
• Group – 10
• Period – 5
• Block – d (transition metal)
• Melting point – 8°C
• Boiling point – 2963°C
• Electronegativity – 2.2 (Pauling scale)
• Density – 12.0 g/cm³

Figure 1: Palladium

Palladium, along with rhodium, ruthenium, osmium, iridium, and platinum, is called the platinum group metals (PGM). The appearance of palladium is very similar to that of platinum. Palladium has the least density and melting point among other chemical elements of platinum group metals.

Palladium has the “face-centered cubic” crystalline structure where the unit cell is in the shape of a cube. Although palladium is corrosion resistant to some extent, it is attacked by hot acids such as concentrated nitric acid, sulfuric acid, etc. Palladium may dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid).

Palladium does not tarnish when exposed to air since it does not react with oxygen at standard temperature. But in a moist atmosphere containing sulfur, palladium tarnishes lightly.

Applications of Palladium

The applications of palladium include followings.

• Used as a catalyst (finely divided palladium is used to speed up hydrogenation, dehydrogenation and petroleum cracking reactions)
• Used in low voltage electrical contacts (due to the corrosion resistance)
• Jewelry making (form alloys named “white gold” – alloy with platinum)
• To make watch bearings, mirrors in scientific instruments, springs, etc.
• Used as catalytic converters for cars (to reduce emissions from car exhaust)
• Electroplating (palladium salts are used)

What is Platinum

Platinum is a chemical element with the symbol Pt and atomic number 78. It has a shiny silvery-white appearance. It is highly unreactive like gold and is highly resistant to corrosion. Platinum is a member of the platinum group metals.

Chemical Properties of Platinum

Some chemical properties of platinum are listed below.

• Atomic number – 78
• Atomic mass – 195.084 g/mol
• Electron configuration – [Xe] 4f¹⁴5d⁹6s¹
• Group – 10
• Period – 6
• Block – d (transition metal)
• Melting point – 2°C
• Boiling point – 3825°C
• Electronegativity – 2.2 (Pauling scale)
• Density – 21.5 g/cm³

Figure 2: Platinum

Platinum is found in alluvial deposits as the free metal (uncombined). Platinum is one of the least reactive metals.

Pure platinum is ductile, malleable and lustrous. When compared with gold and silver, platinum is more ductile but less malleable. Platinum resists reacting with concentrated nitric and hydrochloric acids but is dissolved in hot aqua regia (a mixture of nitric acid and hydrochloric acid).

Applications of Platinum

Some applications of platinum are listed below.

• As jewellery (due to its strength and resistance to tarnish)
• As a catalytic converter for cars, trucks and buses (due to the efficiency of converting emissions from the vehicle’s engine into less harmful waste products.
• As a catalyst for the production of nitric acid, silicone and benzene
• As wires used for electrodes
• For medical uses (platinum compounds are used as chemotherapy drugs)

Difference Between Palladium and Platinum

Definition

Palladium: Palladium is a chemical element with the symbol Pd and atomic number 46.

Platinum: Platinum is a chemical element with the symbol Pt and atomic number 78.

Atomic Number

Palladium: Atomic number of palladium is 46.

Platinum: Atomic number of platinum is 78.

Atomic Mass

Palladium: Atomic mass of palladium is 106.42 g/mol.

Platinum: Atomic mass of platinum is 195.084 g/mol

Melting Point

Palladium: The melting point of palladium is 1554.8°C.

Platinum: The melting point of platinum is 1768.2°C

Density

Palladium: The density of palladium is about 12.0 g/cm³.

Platinum: The density of palladium is about 21.5 g/cm³.

Period

Palladium: Palladium is in the period 5 of the periodic table of elements.

Platinum: Platinum is in the period 6 of the periodic table of elements.

Uses

Palladium: Palladium is used as catalysts, catalytic converters, for electroplating, jewelry making, etc.

Platinum: Platinum is used for jewelry making, as catalytic converters, catalysts, to make drugs in chemotherapy for cancers.

Conclusion

Palladium and platinum are very important metals that have a similar appearance. These metals have a wide variety of applications. Although they look similar, there are many chemical differences between them. The main difference between palladium and platinum is that palladium has the least density and melting point among PGM elements whereas platinum has a considerably high density and a high melting point.

Reference:

1. “Palladium – Element information, properties and uses | Periodic Table.” Royal Society of Chemistry, Available here.
2. “Water Treatment Solutions.” Lenntech Water treatment & purification, Available here.
3. “Platinum – Element information, properties and uses | Periodic Table.” Royal Society of Chemistry, Available here.

Image Courtesy:

1. “Palladium (46 Pd)” By Hi-Res Images ofChemical Elements – (CC BY 3.0) via Commons Wikimedia
2. “Platinum (Russia) 3 (17151299739)” By James St. John – Platinum (Russia) 3 (CC BY 2.0) via Commons Wikimedia