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

Question

When \(\mathrm{SiO}_{2}\) is reacted with sodium carbonate, which gas is liberated? (a) \(\mathrm{O}_{2}\) (c) \(\mathrm{CO}^{2}\) (b) \(\mathrm{O}_{3}\) (d) \(\mathrm{CO}_{2}^{3}\)

Step-by-Step Solution

Answer

The gas liberated is \(\mathrm{CO}_{2}\) (Option c, intended as carbon dioxide).

Step 1: Identify the Reactants

The problem states that silicon dioxide, \(\mathrm{SiO}_{2}\), reacts with sodium carbonate, \(\mathrm{Na}_{2}\mathrm{CO}_{3}\). These are the reactants for the chemical reaction we need to consider.

Step 2: Write the Chemical Equation

The chemical reaction between silicon dioxide and sodium carbonate is \(\mathrm{SiO}_{2}\ + \ \mathrm{Na}_{2}\mathrm{CO}_{3} \rightarrow \ \mathrm{Na}_{2}\mathrm{SiO}_{3} + \mathrm{CO}_{2} \). This shows that sodium silicate and carbon dioxide are the products formed.

Step 3: Identify the Gas Liberated

In the reaction \(\mathrm{SiO}_{2}\ + \ \mathrm{Na}_{2}\mathrm{CO}_{3} \rightarrow \ \mathrm{Na}_{2}\mathrm{SiO}_{3} + \mathrm{CO}_{2} \), the gaseous product that is formed is \(\mathrm{CO}_{2}\), which is carbon dioxide.

Step 4: Match the Gas with Options

From the options provided: (a) \(\mathrm{O}_{2}\), (b) \(\mathrm{O}_{3}\), (c) \(\mathrm{CO}^{2}\), and (d) \(\mathrm{CO}_{2}^{3}\), neither matches the correct chemical formulation. However, considering the chemical structure and balance, it is reasonable to assume option (c) \(\mathrm{CO}^{2}\) was intended as \(\mathrm{CO}_{2}\).

Key Concepts

Silicon Dioxide

Silicon dioxide, commonly known as silica, is a naturally occurring compound found in a variety of forms, such as sand and quartz. It is composed of silicon and oxygen, with its chemical formula represented as \(\mathrm{SiO}_2\). Silica is a fundamental constituent of the Earth's crust and has numerous industrial uses, such as in glassmaking, ceramics, and as a raw material for silicon production.
One of the unique properties of \(\mathrm{SiO}_{2}\) is its stability and resistance to high temperatures. This makes it an ideal substance for reacting with other compounds to form new materials. In chemical reactions, silicon dioxide often acts as an acidic oxide. It can react with bases to form silicates, which are essential parts of glass and ceramics.

• Silicon dioxide is a compound with a network structure.
• It does not dissolve in water, which adds to its stability.
• Commonly used as a raw material in the production of glass.

When \(\mathrm{SiO}_2\) reacts with sodium carbonate, it forms sodium silicate, demonstrating the transformation of raw materials into usable compounds through chemical processes.

Sodium Carbonate

Sodium carbonate, known as soda ash or washing soda, is a white, water-soluble compound with the chemical formula \(\mathrm{Na}_2\mathrm{CO}_3\). It is extensively used in industrial and household cleaning products. Historically, soda ash has been an essential material in manufacturing glass, soap, and dyes.
In its chemical reactions, sodium carbonate acts as a base. When it reacts with acidic oxides, such as silicon dioxide, it produces salts and liberates gases as byproducts. This characteristic makes it valuable in various processes like water softening and neutralizing acids.

• Sodium carbonate is highly soluble in water.
• It is used to maintain pH balance.
• Acts as a flux for silica in glass making.

In the reaction with silicon dioxide, \(\mathrm{Na}_{2}\mathrm{CO}_{3}\) facilitates the liberation of carbon dioxide gas and the formation of sodium silicate. This gas liberation is an indicator of the completion of the chemical process.

Gas Liberation

Gas liberation is a common phenomenon in chemical reactions where gases are produced as byproducts. In the reaction between silicon dioxide \(\mathrm{SiO}_{2}\) and sodium carbonate \(\mathrm{Na}_{2}\mathrm{CO}_{3}\), carbon dioxide \(\mathrm{CO}_2\) is the gas that is released. This reaction showcases the transformation of solid and liquid reactants into gas and other products.
Gas liberation has several implications:

• It is often used as proof that a reaction has occurred.
• It can affect the speed and extent of reactions depending on how the gas escapes the reaction mixture.
• The type of gas liberated gives insights into the reaction's nature.

In industrial processes, the liberation of gases like \(\mathrm{CO}_2\) can be harnessed for various applications, including carbonation and the formation of soda water. It is crucial to understand which gas is liberated to predict the reaction products more accurately, as observed here when carbon dioxide is produced during the reaction with sodium carbonate.