What is the Difference Between Molybdenum and Tungsten

Molybdenum and tungsten are two refractory metals, which are highly resistant to heat. They have very high melting points, which make them useful in applications like aerospace and electrical contacts. These metals maintain their strength and stability at high temperatures. This makes them essential for components that need to withstand extreme conditions.

What is the difference between molybdenum and tungsten? Tungsten is denser and has a much higher melting point than molybdenum. 

Key Areas Covered

1. What is Molybdenum  
      – Definition, Features, Uses
2. What is Tungsten
      – Definition, Features, Uses
3. Similarities Between Molybdenum and Tungsten
      – Outline of Common Features
4. Difference Between Molybdenum and Tungsten
      – Comparison of Key Differences
5. FAQ: Molybdenum and Tungsten
      – Answers to Frequently Asked Questions

Key Terms

Molybdenum, Tungsten

What is Molybdenum

Molybdenum is a silvery grey transition metal that has the atomic number 42. Its chemical symbol is Mo. Molybdenum is present in group 6 of the periodic table. It exists in the oxidation states from -II to +VI. Molybdenum forms stable compounds due to its affinity towards chlorine, fluorine, sulphur and oxygen. It also forms strong bonds with carbon found in organometallic chemistry.

Molybdenum has the ability to act as a catalyst because it forms stable complexes with ligands and has multiple oxidation states. In fact, it acts as a catalyst in a range of industrial processes, such as the hydrodesulfurization (HDS) process, which removes sulfur impurities from petroleum products.

Molybdenum is used in various industrial processes. Its major use is in the production of alloys. It is added to steel in the steel industry in order to enhance its properties in aerospace and automotive industries. Molybdenum-alloyed steels are used to manufacture engine parts, aircraft frames, and other similar components.

Moreover, molybdenum mixed with nickel-based superalloys are used in the production of jet engines, gas turbines, and industrial furnaces due to its high heat resistance. Molybdenum is also a trace element in humans and animals.

What is Tungsten

Tungsten is a silvery white metal with an atomic number of 74, belonging to group 6 in the periodic table. Tungsten has high electronegativity. Due to this property, tungsten forms stable compounds with oxygen (tungstates). The chemical symbol of tungsten is W. The highest and most common oxidation state of tungsten is +6, though it exists in other oxidation states, too. A higher oxidation state indicates its tendency to lose electrons. Tungsten compounds exhibit covalent character due to the high degree of orbital overlap between tungsten and other elements. It forms a variety of coordination compounds with different ligands.

Tungsten is commonly used to produce tungsten carbide, which is very hard. This substance is used in the manufacture of cutting tools, drill bits, and other industrial equipment that require exceptional durability. Tungsten carbide also has a higher density, which is a property that allows it to be used in armor-piercing ammunition.

The high melting point of tungsten is used in manufacturing filaments of incandescent light bulbs. Furthermore, tungsten is used in electrodes for welding and as a target material in X-ray tubes.

Similarities Between Molybdenum and Tungsten

1. Molybdenum and tungsten are classified as refractory metals.
2. Both metals are very hard and strong.
3. Molybdenum and tungsten are both dense metals.
4. Both metals are commonly used as alloying elements.
5. They exhibit excellent resistance to corrosion.

Difference Between Molybdenum and Tungsten

Definition

• Molybdenum is a silvery grey transition metal that has the atomic number 42 while tungsten is a silvery white metal that has the the atomic number 74.

Melting Point

• Tungsten has a much higher melting point than molybdenum.

Density

• Tungsten is denser than molybdenum.

Thermal Conductivity

• Molybdenum has a higher thermal conductivity than tungsten.

Machinability

• Molybdenum is considered more machinable than tungsten.

Cost

• Molybdenum is typically less expensive than tungsten.

Conclusion

There is a distinct difference between molybdenum and tungsten, although both are classified as refractory metals. Molybdenum has a higher thermal conductivity while tungsten is denser and has a much higher melting point. Tungsten is also more expensive than molybdenum.

FAQ: Molybdenum and Tungsten

1. Is tungsten more expensive than molybdenum?

Tungsten is generally more expensive than molybdenum. This high cost is a result of its scarcity and complex extraction process.

2. What is the density of molybdenum vs tungsten?

Tungsten is denser than molybdenum. Tungsten has a density of 19.3 g/cm³, while molybdenum’s density is 10.2 g/cm³. This makes tungsten significantly heavier for its size compared to molybdenum.

3. What is the resistivity of molybdenum vs tungsten?

Both molybdenum and tungsten have low electrical resistivity, which makes them good conductors. However, tungsten has slightly lower resistivity than molybdenum at room temperature.

4. Is molybdenum harder than tungsten?

Tungsten is harder than molybdenum. This property makes tungsten ideal for applications requiring extreme durability, such as light bulb filaments and drill bits.

5. Is molybdenum a heavy metal?

Molybdenum is classified as a heavy metal. However, unlike toxic heavy metals like lead or mercury, it’s essential for human health in trace amounts.

Reference:

1. “Tungsten – Chemical Element.” Encyclopedia Britannica. 
2. “Molybdenum.” Encyclopedia Britannica. 

Image Courtesy:

1. “Wolfram evaporated crystals and 1cm3 cube” By Alchemist-hp (talk) (www.pse-mendelejew.de) – Own work (FAL) via Commons Wikimedia
2. “Molybdenum crystaline fragment and 1cm3 cube” By Alchemist-hp (talk) (www.pse-mendelejew.de) – Own work (FAL) via Commons Wikimedia