Problem 33 - A Complete Resource Book in Chemistry for JEE Main

Question

Sodium metal reacts with \(\mathrm{Al}_{2} \mathrm{O}_{3}\) at high temperature to give a sodium compound X.X reacts with carbon dioxide in water to form \(Y Y\) is ...... (a) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) (b) \(\mathrm{Na}_{4} \mathrm{O}_{2}\) (c) \(\mathrm{NaAlO}_{2}\) (d) \(\mathrm{Na}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

(a) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\)

Step 1: Identify the First Reaction Product

The reaction of sodium metal (Na) with aluminum oxide (Al_2O_3) at high temperature produces sodium aluminate (NaAlO_2). This equation can be represented as:\[\text{Na} + \text{Al}_2\text{O}_3 \xrightarrow{\text{high temperature}} \text{NaAlO}_2\]

Step 2: Determine the Reaction of X with CO2 in Water

The sodium compound X, identified as NaAlO_2, then reacts with carbon dioxide (CO_2) in the presence of water. The reaction forms sodium carbonate (Na_2CO_3). This can be described by the equation:\[2\text{NaAlO}_2 + 3\text{CO}_2 + 3\text{H}_2\text{O} \rightarrow 2\text{Na}_2\text{CO}_3 + 2\text{Al(OH)}_3\]

Step 3: Identify the Resulting Compound Y

From Step 2, we see that when NaAlO_2 reacts with CO_2 in water, it produces Na_2CO_3 . Thus, the resulting compound Y is sodium carbonate ( Na_2CO_3 ).

Key Concepts

Sodium Aluminate Formation

The formation of sodium aluminate is an intriguing reaction that occurs when sodium metal (\(\text{Na}\)) is combined with aluminum oxide (\(\text{Al}_2\text{O}_3\)) under the influence of high temperature. This reaction results in the compound sodium aluminate (\(\text{NaAlO}_2\)), which is known for its industrial applications, particularly in water treatment and as a chemical reagent.

### Understanding the Reaction Context

• Sodium metal, a highly reactive alkali metal, engages in several fascinating reactions with other elements and compounds.
• Aluminum oxide, a well-known ceramic material, acts as an oxidizing agent in this reaction.
• Under sufficient heat, the reactivity of sodium allows it to displace aluminum from \(\text{Al}_2\text{O}_3\), resulting in sodium aluminate.

This reaction not only highlights the reactive nature of sodium but also the ability of metals to form complex compounds through substitution reactions. Sodium aluminate is often encountered as a useful intermediate in various industrial processes, emphasizing the versatility of sodium as a reactive partner in chemical transformations.

Sodium Carbonate Synthesis

Sodium carbonate (\(\text{Na}_2\text{CO}_3\)), also known as "soda ash," is an important industrial chemical. It can be synthesized from sodium aluminate (\(\text{NaAlO}_2\)) through a reaction with carbon dioxide (\(\text{CO}_2\)) and water (\(\text{H}_2\text{O}\)). This is a key step in industrial chemistry for the formation of materials used in glass-making, detergents, and beyond.

### Steps in the Synthesis Reaction

• The initial compound, sodium aluminate, is combined with carbon dioxide. This typically happens in an aqueous solution.
• Water in the reaction helps facilitate the transformation into sodium carbonate, with aluminum hydroxide (\(\text{Al(OH)}_3\)) being formed as a by-product.
• The complete reaction can be represented as:\[2\text{NaAlO}_2 + 3\text{CO}_2 + 3\text{H}_2\text{O} \rightarrow 2\text{Na}_2\text{CO}_3 + 2\text{Al(OH)}_3\]

This transformation highlights how sodium aluminate serves as an intermediate step towards the useful compound, sodium carbonate, showcasing its importance in a chain of chemical reactions that yield valuable compounds for various industries.

Chemical Reaction Analysis

Analyzing chemical reactions like the conversion of sodium aluminate (\(\text{NaAlO}_2\)) is essential for understanding the stoichiometry and outcomes of complex processes. In the realm of chemistry, it is crucial to break down reactions step-by-step to appreciate the balance of reactants and products.

### Importance of Reaction Analysis

• Reaction analysis helps determine the specific conditions required for reactions to occur, such as temperature or the presence of specific catalysts.
• In the reaction of sodium aluminate with carbon dioxide, analysis shows the balance of elements, ensuring the law of conservation of mass is upheld.
• Each transformation provides insights into potential by-products, which can illuminate side reactions or alternative pathways.

Analysts look at each atom and molecule involved in reactions to unravel not just how products are formed, but why specific reactions prefer certain pathways over others. By examining these chemical processes in detail, chemists can optimize reactions for efficiency and minimize unwanted byproducts, thereby improving industrial and laboratory syntheses.