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) \(\mathrm{Na}_{2} \mathrm{O}\)

Short answer

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

Step-by-step solution

Write Chemical Reaction of Sodium with Al2O3

First, identify the reaction between sodium (Na) and aluminum oxide (\(\mathrm{Al}_2 \mathrm{O}_3\)). When sodium reacts with \(\mathrm{Al}_2 \mathrm{O}_3\) at high temperatures, the reaction can produce sodium aluminate (\(\mathrm{NaAlO}_2\)). The balanced chemical equation is: \[\ 2\, \mathrm{Na} + \mathrm{Al}_2 \mathrm{O}_3 \rightarrow 2\, \mathrm{NaAlO}_2\ + \mathrm{Al}\] Therefore, compound X in this scenario is \(\mathrm{NaAlO}_2\).

Reaction of X with CO2 and Water

Now, consider how \(\mathrm{NaAlO}_2\) reacts with carbon dioxide (\(\mathrm{CO}_2\)) and water. When sodium aluminate reacts with \(\mathrm{CO}_2\) in an aqueous environment, the reaction results in the formation of sodium bicarbonate or carbonate. Given the options, the most suitable product is \(\mathrm{Na}_{2} \mathrm{CO}_{3}\). The equation for this process can be stated as follows:\[2\, \mathrm{NaAlO}_2 + \mathrm{CO}_2 + 3\, \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Na}_2\mathrm{CO}_3 + 2\, \mathrm{Al(OH)}_3\] Thus, compound Y is \(\mathrm{Na}_2 \mathrm{CO}_3\).

Key concepts

Sodium Aluminate

Sodium aluminate is an interesting compound formed when sodium metal reacts with aluminum oxide (\(\mathrm{Al}_2 \mathrm{O}_3\)) at high temperatures. In this process, the compound \(\mathrm{NaAlO}_2\) is produced. This compound is known as sodium aluminate. Understanding the formation of sodium aluminate involves looking at the balanced chemical reaction:

• \[ 2 \mathrm{Na} + \mathrm{Al}_2 \mathrm{O}_3 \rightarrow 2 \mathrm{NaAlO}_2 + \mathrm{Al} \]

This reaction shows that two molecules of sodium are needed to react with aluminum oxide to produce two molecules of sodium aluminate. It's significant in various industrial processes, such as

• water treatment,
• construction materials, and
• wastewater treatment.

Sodium aluminate ensures the formation of aluminum hydroxide, which can act as a coagulant to purify water.

Chemical Reactions

Chemical reactions are a vital part of chemistry, showing how substances interact with each other to form new products. In our previous example, sodium reacting with aluminum oxide illustrates a synthesis reaction, where two simple substances come together to form a more complex compound. Understanding chemical reactions involves recognizing:

• Reactants: The beginning substances (e.g., sodium and aluminum oxide)
• Products: The resulting substances after the reaction (e.g., sodium aluminate and aluminum)
• Balanced Equations: Ensuring the number of atoms for each element matches on both sides of the equation.

Balance is crucial as it reflects the conservation of mass in a reaction, ensuring atoms are neither created nor destroyed. In our sequence, we also encounter the reaction of sodium aluminate with carbon dioxide and water, resulting in sodium carbonate. This demonstrates how environmental factors like water can drive specific chemical changes forward.

Sodium Carbonate

Sodium carbonate, commonly known as soda ash or washing soda, is the end product when sodium aluminate reacts with carbon dioxide and water. In the context of our problem, sodium carbonate \(\mathrm{Na}_2 \mathrm{CO}_3\) is also referred to as compound Y, formed in the reaction:

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

This versatile chemical is widely used in industry and academia. Sodium carbonate plays a crucial role in manufacturing glass, where it reduces the melting point of silica. Additionally, it serves as a water softener in laundry detergents, as it can effectively remove calcium ions. Understanding these interactions helps us see how sodium compounds like sodium aluminate and sodium carbonate are utilized in daily life applications, making this knowledge both theoretical and practical.