Question

CO forms a volatile compound with: (a) Copper (b) Nickel (c) Aluminium (d) Sodium

Short answer

Nickel forms a volatile compound with CO.

Step-by-step solution

Understand the Formation of Metal Carbonyls

Carbon monoxide (CO) can form a compound known as a metal carbonyl with certain metals under specific conditions. These compounds are unique because they involve coordination between the metal and the carbon monoxide molecules.

Examine the Properties of Nickel

Nickel (Ni) is a transition metal that can readily form a volatile carbonyl compound, namely nickel carbonyl (Ni(CO)_4). This metal carbonyl is notable for being one of the few that can form under standard conditions.

Assess Other Metals for Carbonyl Formation

Compare the other metals provided in the question: - Copper, aluminium, and sodium do not readily form volatile carbonyls under normal conditions. - Copper and aluminium form metal carbonyls but they are not volatile. - Sodium typically does not form carbonyls with CO.

Conclusion

Given the options, nickel is the metal that forms a volatile compound with carbon monoxide under typical conditions. Nickel carbonyl is the only compound among the options that is both a carbonyl and volatile.

Key concepts

Transition Metals

Transition metals are a fascinating group of elements located in the central block of the periodic table, specifically in groups 3 to 12. They are commonly known for their ability to form colorful compounds and their widespread use in various industrial applications. Transition metals, such as iron, copper, and nickel, possess partially filled d-orbitals. This allows them to form complex coordination compounds.

These metals are unique because they can lose different numbers of electrons to form various positively charged ions. The partially filled d-orbitals can be used to form bonds with molecules, like carbon monoxide, which engage in something called "coordination bonding." This property is what allows them to form metal carbonyls. Transition metals are generally good conductors of electricity and heat, which is why they are often used in electrical applications.

Nickel Carbonyl

Nickel carbonyl, denoted by the chemical formula \(\text{Ni(CO)}_4\), is a fascinating example of a metal carbonyl compound formed by nickel, a transition metal. This compound is noteworthy due to its volatility and use in various industrial applications. Nickel carbonyl is a mono-nuclear metal carbonyl, meaning it contains only one nickel atom per molecule.

The formation of nickel carbonyl is quite interesting. Under standard conditions, nickel reacts with carbon monoxide to produce this compound. It is also highly volatile, which means it can easily transition into the gas phase at room temperature, making it different from many other metal carbonyls that are non-volatile.

This compound, however, is extremely toxic and hazardous. Because of its ability to release carbon monoxide gas when decomposed, handling nickel carbonyl requires extreme caution.

Coordination Compounds

Coordination compounds are a class of complex compounds that are formed through coordinate bonds between a central metal atom or ion and a set of surrounding molecules or ions, known as ligands. These ligands have lone pairs of electrons that they donate to the metal, forming a coordinate covalent bond. This bonding pattern is a distinctive feature of transition metals, which makes them ideal candidates for forming these compounds.

In the case of nickel carbonyl, the central nickel atom is surrounded by carbon monoxide ligands. CO acts as a ligand that donates electron pairs from the carbon atom to form a bond with the nickel. This results in a stable complex, even though CO is typically a simple gas molecule.

Coordination compounds have significant importance in various fields, such as catalysis, biological systems, and material science. They are often used to tailor specific reactions and create new materials.

Volatile Compounds

Volatile compounds are substances that readily vaporize at relatively low temperatures. This property means that they have a high tendency to move into the gas phase even under standard conditions. Nickel carbonyl is a prime example of a volatile compound due to its ability to shift quickly from liquid to gas at room temperature.

The volatility of a compound is influenced by its molecular structure and intermolecular forces. Weaker intermolecular forces usually imply higher volatility. In metal carbonyls like nickel carbonyl, the volatility can be partially attributed to the symmetrical structure that helps balance dipole interactions.

Volatile compounds find applications in numerous industrial and scientific processes, including those involving separation techniques or synthesis processes where swift transfer to the gas phase is advantageous. The volatility also implies stringent safety measures, especially for toxic substances like nickel carbonyl.