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) \(\mathrm{Na}_{2} \mathrm{O}_{2}\) (c) \(\mathrm{NaAlO}_{2}\) (d) \(\mathrm{Na}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

Y is \(\mathrm{Na}_{2} \mathrm{CO}_3\) (sodium carbonate).

Step 1: Reaction Between Sodium Metal and Aluminum Oxide

Sodium metal reacts with aluminum oxide (\(\mathrm{Al}_{2} \mathrm{O}_{3}\)) at high temperature. This reaction forms sodium aluminate (\(\mathrm{NaAlO}_{2}\)). The balanced chemical equation is:\[ 6 \mathrm{Na} + \mathrm{Al}_{2} \mathrm{O}_{3} \rightarrow 2 \mathrm{NaAlO}_{2} + \frac{1}{2} \mathrm{Al} \]

Step 2: Reacting Sodium Aluminate with Carbon Dioxide in Water

Sodium aluminate (\(\mathrm{NaAlO}_{2}\)) reacts with carbon dioxide (\(\mathrm{CO}_2\)) in water to ultimately form sodium carbonate (\(\mathrm{Na}_{2} \mathrm{CO}_3\)) and aluminum hydroxide (\(\mathrm{Al(OH)}_3\)). This can be represented as:\[ 2 \mathrm{NaAlO}_{2} + 3 \mathrm{H}_{2}\mathrm{O} + \mathrm{CO}_{2} \rightarrow 2 \mathrm{NaOH} + 2 \mathrm{Al(OH)}_3 + \mathrm{Na}_{2} \mathrm{CO}_{3} \]

Step 3: Identify the Compound Y

From the reaction mentioned in step 2, we observe that the reaction between sodium aluminate and carbon dioxide in water produces sodium carbonate. Therefore, compound Y is sodium carbonate (\(\mathrm{Na}_{2} \mathrm{CO}_3\)).

Key Concepts

Sodium Aluminate

Sodium aluminate is a fascinating compound that emerges when sodium metal reacts with aluminum oxide at high temperatures. The reaction between sodium and aluminum oxide, or \(\mathrm{Al}_2\mathrm{O}_3\), involves the formation of sodium aluminate, which has the chemical formula \(\mathrm{NaAlO}_2\). This is a key step in the entire reaction sequence.

You might wonder why sodium aluminate is important. Well, it's not only useful in chemical reactions but also finds applications in water treatment processes. The balanced reaction that creates sodium aluminate from sodium and aluminum oxide is:

• 6 \(\mathrm{Na} + \mathrm{Al}_2 \mathrm{O}_3 \rightarrow 2 \mathrm{NaAlO}_2 + \frac{1}{2} \mathrm{Al} \)

Knowing this reaction equation helps you understand how different elements combine to form this useful compound.

Sodium Carbonate

Sodium carbonate, also commonly known as soda ash or washing soda, is a versatile compound produced through a specific chemical reaction that interests many chemistry students. In our context, sodium carbonate forms when sodium aluminate reacts with carbon dioxide in water. This process not only gives us sodium carbonate but also aluminum hydroxide.

The balanced chemical equation for the reaction is:

• \( 2 \mathrm{NaAlO}_2 + 3 \mathrm{H}_2 \mathrm{O} + \mathrm{CO}_2 \rightarrow 2 \mathrm{NaOH} + 2 \mathrm{Al(OH)}_3 + \mathrm{Na}_2 \mathrm{CO}_3 \)

Sodium carbonate is highly important in many industrial processes, such as glass-making, and it plays a crucial role in our exercise as the sought-after compound, identified as "Y".

Chemical Equations

Chemical equations are vital tools in understanding and expressing chemical reactions. They provide a concise way to represent how substances interact and transform in reactions. In our example, the chemical equations not only showed how sodium aluminate is formed from sodium and aluminum oxide but also how it reacts with carbon dioxide to generate sodium carbonate.

A chemical equation presents information such as:

• The reactants, or the starting substances
• The products, or the compounds formed
• The stoichiometric coefficients that denote the proportions of each substance involved

Mastering these details allows one to predict product formation and understand the conservation of mass in reactions.

Reaction with Carbon Dioxide

When you think of carbon dioxide, you might imagine the gas we emit when we breathe out. However, in chemistry, carbon dioxide is a reactive substance that can participate in various chemical processes. In the exercise, carbon dioxide reacts with sodium aluminate and water to yield sodium carbonate.

The reaction involving carbon dioxide is important because it showcases how gases can create new compounds when mixed with other substances. The resulting sodium carbonate has extensive practical uses, particularly in household products and manufacturing sectors. Understanding such reactions involving carbon dioxide emphasizes the remarkable nature of gaseous interactions in forming solid compounds.