Palladium

Palladium: Its Property and Usages

In chemistry, the study of metals and their property is known as metallurgy. If you check past question papers, you can see that the weightage of this topic is quite higher in all board and national competitive examinations. By studying metallurgy, you can learn the usage of metals and their related properties.

Palladium is one of the most expensive metals in present days due to its various usage in a different industry. Majorly, in the automobile industry, palladium use has increased as this metal can reduce the emitted pollution from vehicles.

Palladium Element

Palladium is known by the symbol “Pd” and is one of the six metals in the platinum group. With atomic number 46, this metal belongs to group number 10 and period number 5 of the periodic table. In 1803, William Hyde Wollaston, an English chemist first found out this shinning silver-white metal and named this after the asteroid Pallas.

Chemical Properties

Palladium Use

Among all platinum metals, palladium has one of the highest abundances. Moreover, it is highly ductile. Thus, this metal has several uses in different industries. Here are some important palladium uses below-

• The primary use of Pd is automobile industry as catalytic converters. Mostly, combining with rhodium, Pd is used as a catalyst that can convert all automobile exhausts like nitrogen oxide, carbon monoxide, and hydrocarbons into less polluting agents such as carbon dioxide, nitrogen, and water.

•  Palladium coatings that are chemically plated are one of the components of printed circuits. Moreover, its salts are also used for black and white photograph printings.

• In multi-layered ceramic capacitors and electrodes, you can also find the use of these metals.

• Furthermore, it is also used to store hydrogen as palladium can absorb this gas in huge amount.

• At standard temperature, atmospheric conditions cannot tarnish it. Hence, palladium and all its alloys are used as platinum alternatives in jewellery and electrical industry.

• Relatively lesser quantity of this metal can alloy with gold to produce white gold as well. 

• Palladium can also be used in dentistry as dental alloys.

• Pd is one of the most common metals used to manufacture surgical instruments.

• Lastly, other than these usages, Pd element is also found in groundwater treatments, medicine, electronics, etc. 

Now, let us see how much did you learn from the above information.

Quiz 1.0

1. How can you Classify a Palladium Element? Choose from the Following Options.

1. Transition metal

2. Noble gas

3. Group 2 metal

4. Non-metal

2. Who from the Below List Discovered the Pd Element?

1. Neils Bohr

2. William Hyde Wollaston

3. Albert Einstein

4. Alfred Nobel

3. Which One from the Following Applications Does not Find Palladium Use in?

1. Jewellery

2. Catalytic converters in automobiles

3. Roadway makers

4. Instruments to perform surgery

4. Palladium was Found Out in Which Century?

1. 1800’s

2. 1900’s

3. 1500’s

4. 1300’s

5. How Many Radioactive Isotopes Does Palladium have?

1. 21

2. 22

3. 20

4. 24

Answers

1. a. Palladium is a transition metal as this metal has a tendency to create coordination compounds and furnishes variable valency.

2. b. William Hyde Wollaston found out palladium first.

3. c. Roadway makers do not find any use of Pd.

4. b. In 1900’s century Pd was discovered.

5. a. Palladium has 21 radioactive isotopes.

Properties of Palladium

• In Physical appearance, Pd is a silvery-white coloured metal that can resist tarnishing.

• This metal can be considered as fairly non-toxic as it does not have any significant biological role. However, Pd can trigger allergies depending on the sensitivity of individuals.

• Palladium can be found in both combined and detached state.

• Even though all platinum metals are alike in chemical properties, palladium holds the lowest density and melting point of them.

• Nonetheless, it is the most reactive among all platinum group metals or PGMs. 

• Nitric acid can dissolve palladium slowly and results in palladium (II) nitrate.

Here is the chemical equation:

Pd + HNO3 🡪 Pd(NO3)2 + NO2 + H2O

• Pd readily reacts with aqua regia at room temperature. Aqua regia is a 1 : 3 proportionate mixture of nitric acid and hydrochloric acid. And the reaction results in palladium (II) chloride, nitrosyl chloride, and water.

Pd + HNO3 + 3 HCl 🡪 PdCl2 + NOCl + 2 H2O

• Palladium also reacts with concentrated sulfuric acid and creates palladium (II) sulfate, water, and sulfur dioxide at near about 80oC temperature.

Pd + 2 H2SO4 🡪 PdSO4 + SO2 + 2 H2O

• In the presence of additional oxygen and chlorine, hydrochloric acid can dissolve the sponge form of palladium and produce palladium (II) chloride and water.

2 Pd + 4 HCl + O2 🡪 2 PdCl2 + 2 H2O

• On heating, palladium combines with non-metal elements like sulphur, phosphorus, antimony, arsenic, selenium, and silicon as well.

• With various oxidation states, palladium compounds can be produced.

• Palladium is one of the transition metals that have a high tendency to bond with carbon.

• Its compounds can easily be decomposed to liberate the metals.

Electron Configuration

Pd electron configuration is expressed as [Kr] 4d10. The atomic number of palladium is 46. And the atomic number equals to the proton and neutron number separately. The electron configuration shows the distributions of electrons of any molecule in its molecular orbits.

By electron configuration, the chemical bonding between atoms is demonstrated. Here is the Pd electron configuration-

1s2 – 2 electrons

2s2, 2p6 – 8 electrons

3s2, 3p6, 3d10 – 18 electrons

4s2, 4p6, 4d10 – 18 electrons

Compounds of Palladium

Mostly, palladium compounds can exist in +2 and 0 state. However, there are some other oxidation states can also be found.

Palladium (II)

Palladium (II) chloride is produced by the chemical reaction between palladium and chlorine. It is the main starting material used to form other heterogeneous Pd compounds with carbon and sulphate. In nitric acid, PdCl2 solution reacts with acetic acid and produces palladium acetate that is a known versatile reagent.  Palladium (II) chloride also reacts with ligands such as PhCN, NH3, PPh3, etc. to create planar complexes of PdCl2L2 type.

PdCl2 + 2 L 🡪 PdCl2L2

Palladium (0)

Palladium can also create various zerovalent complexes as PdL2, PdL3, and PdL4. For instance, a mixture of PPh3 and PdCl2(PPh3) produces tetrakis palladium (0).

2 PdCl2(PPh3) + 4 PPh3 + 5 N2H4🡪 2 Pd(PPh3)4 + N2 + 4 N2H5+Cl-

Other than these two oxidation states, Pd (IV) compounds like sodium hexachloropalladate is also found.

Occurrence

In Brazil, palladium is abundance as an uncombined state. However, mostly, it is present in nature as braggite, a sulphide mineral. During nickel, zinc, and copper refining, palladium is commercially extracted as the by-product.

Norilsk mining centre of Russia is the biggest palladium producer in the world. This country is followed by South Africa, Canada, and America.

True and False

1. The Melting Point of Gold is Lower than Palladium’s Melting Point-

1. True

2. False

2. Palladium is One of the Major Components in Fuel Cells-

1. True

2. False

3. Canada is the Highest Producer of Pd-

1. True

2. False

4. Palladium Gets Tarnish Easily-

1. True

2. False

5. Palladium has 46 Electrons-

1. True

2. False

6. Pd is a Group 1 Metal-

1. True

2. False

7. Pd Does not React with Aqua Regia-

1. True

2. False

8. 110Pd is the Key Isotope of Palladium-

1. True

2. False

9. Palladium is Used in Hydrogen Refinement-

1. True

2. False

10. Pd has a Low Toxicity Level-

1. True 

2. False

Solutions

1. a. Ture. Gold’s melting point – 1064oC.

2. a. True

3. b. False

4. b. False

5. a. True

6. b. False

7. b. False

8. b. False

9. a. True

10. a. True

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