Question

Tungsten carbide is (1) one of the hardest substance known (2) an interstitial compound (3) a berthalloid compound (4) all the above

Short answer

The correct answer is (4) all the above.

Step-by-step solution

Title - Analyze the Options

Examine the given options to identify the characteristics of tungsten carbide. The options are: (1) one of the hardest substances known, (2) an interstitial compound, (3) a berthalloid compound, and (4) all the above.

Title - Verify Hardness

Check whether tungsten carbide is known for its hardness. Tungsten carbide is indeed one of the hardest materials known, primarily used in cutting tools and abrasives.

Title - Determine Compound Type

Identify if tungsten carbide is an interstitial compound. An interstitial compound is formed when small atoms fit into the interstices (gaps) between larger atoms in a crystal lattice. Tungsten carbide fits this definition as carbon atoms are small and fit into the tungsten lattice.

Title - Examine Berthalloid Compound

Check if tungsten carbide can be categorized as a berthalloid compound. A berthalloid compound is a type of non-stoichiometric compound where the element ratios are not fixed but vary within certain limits. Tungsten carbide does meet this criterion.

Title - Conclude Correct Option

Since tungsten carbide meets all the characteristics described in options 1, 2, and 3, the correct answer must be option 4: all the above.

Key concepts

hardness

Tungsten carbide is renowned for its exceptional hardness. This makes it one of the hardest substances known to mankind. Hardness is a measure of a material's ability to resist indentation and scratching. Tungsten carbide showcases a hardness of 9 to 9.5 on the Mohs hardness scale, nearly approaching the hardness of diamond, which is the hardest known natural material and is rated at 10 on the Mohs scale.

Because of this property, tungsten carbide is widely used in

• cutting tools
• abrasives
• industrial machinery
• drill bits

These applications require materials that can withstand significant wear and tear without losing their functionality.

Understanding the hardness of tungsten carbide helps in numerous industries as they rely on materials that perform well under pressure and demanding conditions.

interstitial compounds

Tungsten carbide is classified as an interstitial compound. Interstitial compounds form when small atoms, like carbon, fit into the spaces (interstices) between larger atoms in a crystal lattice. In the case of tungsten carbide, carbon atoms occupy the interstitial spaces within the tungsten metal lattice.

Such compounds are typically

• very hard
• chemically stable
• have high melting points

These characteristics are attributed to the intercalation of smaller atoms, which strengthens the overall lattice structure. The interstitial nature of tungsten carbide also gives it notable properties like resistance to deformation and extraordinary strength, making it ideal for tough environments.

This concept is important for students to grasp as it explains why tungsten carbide performs so well compared to other metals and alloys in similar applications.

berthalloid compounds

Tungsten carbide fits the definition of a berthalloid compound. Berthalloid compounds, also known as non-stoichiometric compounds, have variable composition ratios. This means that the elements in these compounds do not adhere to a fixed ratio but vary within certain limits.

For tungsten carbide, the ratio of tungsten to carbon can fluctuate, allowing the material to adapt its properties slightly for different applications. These compounds are advantageous because they

• allow for a range of material properties
• enable fine-tuning for specific needs
• maintain stability across various compositions

Knowing about berthalloid compounds helps understand the flexibility and adaptability in the use of materials like tungsten carbide, which can be tailored to meet specific industrial requirements.

This property is crucial in metallurgy and materials science where specific material characteristics are essential for different engineering applications.