Question

Consider the following statements: 1\. Atomic hydrogen is obtained by passing hydrogen through an electric arc. 2\. Hydrogen gas will not reduce heated aluminium oxide. 3\. Finely divided palladium absorbs large volume of hydrogen gas. 4\. Pure nascent hydrogen is best obtained by reacting Na with \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\). Which of the above statements is/are correct? (a) 1 alone (b) 2 alone (c) 1,2 , and 3 (d) 2,3 and 4

Short answer

(c) 1, 2, and 3

Step-by-step solution

Analyze Statement 1

Atomic hydrogen is obtained by passing hydrogen through an electric arc. This statement is correct. An electric arc can dissociate molecular hydrogen into atomic hydrogen, commonly used in arc welding.

Analyze Statement 2

Hydrogen gas will not reduce heated aluminium oxide. This statement is also correct. Aluminium oxide is stable and cannot be reduced by hydrogen gas under normal conditions.

Analyze Statement 3

Finely divided palladium absorbs large volumes of hydrogen gas. This statement is correct. Palladium has a unique capacity to absorb hydrogen gas, forming what is sometimes called palladium hydride.

Analyze Statement 4

Pure nascent hydrogen is best obtained by reacting Na with \( \mathrm{C}_{2}\mathrm{H}_{5} \mathrm{OH} \). This statement is incorrect. Nascent hydrogen is generally considered a theoretical concept, not obtained by this mentioned reaction.

Determine Correct Statements

Statements 1, 2, and 3 are correct based on their individual analyses, while statement 4 is incorrect. Therefore, the correct option is (c) 1, 2, and 3.

Key concepts

Atomic Hydrogen

Atomic hydrogen refers to the individual hydrogen atoms that can be produced by dissociating molecular hydrogen. This process typically involves using an electric arc. The electric arc provides the necessary energy to break the H-H bonds in the hydrogen molecule. Consequently, it separates into two individual hydrogen atoms, known as atomic hydrogen.
Once produced, atomic hydrogen is highly reactive. It doesn’t exist freely in nature for long because it quickly recombines to form molecular hydrogen. Given its high reactivity, atomic hydrogen is quite useful in industrial applications, like atomic hydrogen welding (AHW). In AHW, the heat generated by the recombination of atomic hydrogen into molecular hydrogen is used to melt metals, allowing precise welding even with materials having high melting points.
Atomic hydrogen is important in many chemical reactions, serving both as a reactive species and a participant in reducing reactions in some chemical processes.

Hydrogen Reduction

Hydrogen reduction involves the process of removing oxygen from a compound or reducing the oxidation state by adding hydrogen. This type of reaction is often seen in metallurgy and other chemical processes. However, not all oxides are reduced by hydrogen readily.
For example, aluminium oxide is quite stable and resistant to reduction by hydrogen gas because of its strong Al-O bonds. This is why statement 2 from the exercise is correct; hydrogen gas, especially under normal conditions, cannot reduce aluminium oxide.
It's important to recognize that the efficacy of hydrogen as a reducing agent depends greatly on the stability and bonds within the oxide in question. In cases where hydrogen is effective, these reactions are highly beneficial, often used in refining metals from their ores, showcasing one of hydrogen's roles in chemistry beyond its molecular form.

Palladium Absorption

Absorption of hydrogen by palladium is a fascinating phenomenon. Palladium, a precious metal, can absorb significant volumes of hydrogen gas. This process is sometimes referred to as absorption, and it resembles how a sponge takes in water.
This capability of palladium is due to its crystal structure, which allows hydrogen atoms to enter and occupy spaces within, forming palladium hydride.

• Palladium can absorb up to 900 times its own volume of hydrogen.
• The absorption process is reversible, making palladium hydrides a storage medium for hydrogen gas.
• Palladium’s unique ability is used in purification processes, hydrogen sensors, and in some hydrogen storage applications.

This remarkable property of palladium not only underscores its industrial significance but also illustrates the versatile nature of hydrogen's interaction with different elements. Understanding this process is crucial for advancements in hydrogen storage technologies and applications.