Problem 22 - A Complete Resource Book in Chemistry for JEE Main

Question

Sodium is heated in air at \(300^{\circ} \mathrm{C}\) to form X.X absorbs \(\mathrm{CO}_{2}\) and forms \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) and \(\mathrm{Y}\). Which of the following is \(\mathrm{Y}\) ? (a) \(\mathrm{O}_{2}\) (b) \(\mathrm{O}_{3}\) (c) \(\mathrm{H}_{2}\) (d) \(\mathrm{H}_{2} \mathrm{O}_{2}\)

Step-by-Step Solution

Answer

There is no additional \(Y\) produced from this reaction.

Step 1: Understand the Reaction

When sodium is heated in air, it reacts with oxygen to form sodium oxide. The reaction can be written as: \[4 \text{Na} + \text{O}_2 \rightarrow 2 \text{Na}_2\text{O}.\] This means sodium oxide \(\text{Na}_2\text{O}\) is the compound \(X\).

Step 2: Reaction of X with CO2

The sodium oxide \(X = \text{Na}_2\text{O}\) reacts with \(\text{CO}_2\) to form sodium carbonate and a by-product \(Y\). This reaction can be written as: \[\text{Na}_2\text{O} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3.\] No additional elements or compounds are formed as \(Y\), as all oxygen atoms are accounted for in the sodium carbonate.

Step 3: Determine the Product Y

Review the given options to find that the missing product \(Y\) cannot be \(\text{O}_2\), \(\text{O}_3\), or \(\text{H}_2\), because no additional oxygen or hydrogen gases are produced in the above mentioned reaction. Instead, any deviation or intermediate typically isn't indicated, so the answer remains the absence of an extra product in its formation.

Step 4: Choose the Correct Option for Y

Given no \(Y\) is actually formed, the other options (\(\text{O}_2\), \(\text{O}_3\), \(\text{H}_2\), and \(\text{H}_2\text{O}_2\)) do not fit the result of this reaction format. Thus, the answer could be inferred as no production of \(Y\) under the problem's constraints.

Key Concepts

Sodium Oxide Formation

Sodium oxide formation is an interesting chemical reaction involving sodium and oxygen. When sodium, a reactive metal, is heated in air, it reacts vigorously with oxygen to form sodium oxide. This reaction occurs at temperatures around \(300^{\circ} \text{C} \). Sodium molecules interact with oxygen molecules in the atmosphere. The chemical equation representing this reaction is:

• \(4 \text{Na} + \text{O}_2 \rightarrow 2 \text{Na}_2\text{O}\)

Each sodium atom donates an electron to form a sodium ion, \(\text{Na}^+\), while oxygen receives these electrons to form oxygen ions, \(\text{O}^{2-}\). These ions combine to create \(\text{Na}_2\text{O}\), a stable compound.The sodium oxide produced is whitish in appearance and can readily absorb moisture and carbon dioxide from the air, which leads to subsequent chemical reactions.

Sodium and Oxygen Reaction

The reaction between sodium and oxygen is a crucial part of understanding how compounds are formed. This process is an example of a redox reaction, where oxidation and reduction take place simultaneously. Sodium undergoes oxidation as it loses electrons:

• \(\text{Na} \rightarrow \text{Na}^+ + e^-\)

Oxygen is reduced by gaining these electrons:

• \(\text{O}_2 + 4e^- \rightarrow 2 \text{O}^{2-}\)

The resulting \(\text{Na}_2\text{O}\) signifies a typical ionic compound formation where positively charged sodium ions and negatively charged oxygen ions are attracted to each other, forming stable ionic bonds. Understanding this process outlines the principles of ionic bonding, where metals tend to lose electrons and nonmetals gain electrons to achieve a stable electronic configuration. This reaction releases energy, which is why it occurs spontaneously and energetically when sodium is heated.

Sodium Carbonate Production

Sodium carbonate production from sodium oxide and carbon dioxide is another classic chemical transformation. When sodium oxide \(\text{Na}_2\text{O}\) reacts with carbon dioxide \(\text{CO}_2\), it forms sodium carbonate \(\text{Na}_2\text{CO}_3\), a very useful industrial compound. The chemical reaction can be written as:

• \(\text{Na}_2\text{O} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3\)

In this equation, the oxide ion \(\text{O}^{2-}\) in \(\text{Na}_2\text{O}\) is replaced by the carbonate ion \(\text{CO}_3^{2-}\) from \(\text{CO}_2\), resulting in the formation of sodium carbonate. No additional products are formed in this reaction, thereby leaving no room for the formation of elements like oxygen or hydrogen gases. This reaction is an example of a synthesis reaction where simpler substances combine to form a more complex substance. Sodium carbonate itself is widely used in detergents, glass manufacturing, and as a water softener.