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) \(\mathrm{O}_{2}\) (b) \(\mathrm{O}_{3}\) (c) \(\mathrm{CO}\) (d) \(\mathrm{CO}_{2}\)

Step-by-Step Solution

Answer

The gas liberated is \(\mathrm{CO}_{2}\).

Step 1: Understanding the Reaction

To solve this problem, we need to understand what happens when silicon dioxide ( \(\mathrm{SiO}_{2}\)) reacts with sodium carbonate (\(\mathrm{Na}_{2}\mathrm{CO}_{3}\)). The products of this reaction typically include a silicate compound, sodium silicate (\(\mathrm{Na}_2\mathrm{SiO}_3\)), along with a gas byproduct.

Step 2: Writing the Chemical Equation

Write the balanced chemical equation for the reaction between \(\mathrm{SiO}_{2}\) and \(\mathrm{Na}_{2}\mathrm{CO}_{3}\). The equation is:\[ \mathrm{SiO}_{2(s)} + \mathrm{Na}_{2}\mathrm{CO}_{3(s)} \rightarrow \mathrm{Na}_{2}\mathrm{SiO}_{3(s)} + \mathrm{CO}_{2(g)} \]From this equation, we can see that carbon dioxide (\(\mathrm{CO}_{2}\)) is the gas that is liberated.

Step 3: Identifying the Gas Produced

From the balanced chemical equation, it is clear that \(\mathrm{CO}_{2}\) is the gas that is released when \(\mathrm{SiO}_{2}\) reacts with \(\mathrm{Na}_{2}\mathrm{CO}_{3}\).

Key Concepts

Silicon Dioxide

Silicon Dioxide, often represented as \(\mathrm{SiO}_2\), is the principal component of sand and is found in nature as quartz. It is a compound composed of silicon and oxygen, two of the most abundant elements in the Earth's crust.
Here are some key properties and characteristics of silicon dioxide:

• Structural Form: Silicon dioxide has a tetrahedral structure where each silicon atom is covalently bonded to four oxygen atoms.
• Physical Appearance: It is most commonly found as a colorless crystal.
• Chemical Properties: It is very stable and does not react easily with other substances.

In chemical reactions, silicon dioxide can act as an acid, especially when reacting with bases. This behavior is explained by its ability to form silicates when paired with certain metals or compounds.

Sodium Carbonate

Sodium Carbonate, with its chemical formula \(\mathrm{Na}_2\mathrm{CO}_3\), is commonly referred to as washing soda or soda ash. It is a widely used chemical with numerous industrial applications.

• Composition: Made up of sodium, carbon, and oxygen.
• Physical Appearance: It appears as a white, odorless powder.
• Solubility: Highly soluble in water, making it useful in various aqueous chemical reactions.

In chemical processes, sodium carbonate acts as a base. It is often used to neutralize acids and is essential in reactions such as the one with silicon dioxide, where it provides the carbonate ions \((\mathrm{CO}_3^{2-})\) that lead to the release of carbon dioxide. Sodium carbonate’s reactivity and solubility make it invaluable in the production of glass, where it helps to lower the melting point of the sand.

Balanced Chemical Equation

A balanced chemical equation is crucial for accurately representing the reactants and products in a chemical reaction. In such an equation, the number of each type of atom is the same on both sides of the equation, which is necessary to adhere to the law of conservation of mass.
Consider the reaction between silicon dioxide \((\mathrm{SiO}_{2})\) and sodium carbonate \((\mathrm{Na}_2\mathrm{CO}_3)\):

• The balanced equation is:
  \[ \mathrm{SiO}_{2(s)} + \mathrm{Na}_{2}\mathrm{CO}_{3(s)} \rightarrow \mathrm{Na}_{2}\mathrm{SiO}_{3(s)} + \mathrm{CO}_{2(g)} \]
• Mass Balance: There is one silicon atom, three oxygen atoms, and two sodium atoms on both sides.
• Gas Release: Carbon dioxide \((\mathrm{CO}_2)\) is the gaseous byproduct of the reaction.

Balancing is essential for predicting the quantities of reactants needed and products formed. It ensures that the stoichiometry of the reaction is correct, allowing chemists to calculate how much of each substance should be used or expected in a reaction.