Question

The chemical formula of zeolite is \(\ldots \ldots\) (a) \(\mathrm{Na}_{2} \mathrm{Al}_{2} \mathrm{Si}_{2} \mathrm{O}_{8} \cdot \mathrm{xH}_{2} \mathrm{O}\) (b) \(\mathrm{Na}_{2}\left(\mathrm{Na}_{4}\left(\mathrm{PO}_{3}\right)_{6}\right.\) (c) \(\mathrm{Ca}_{2} \mathrm{Al}_{2} \mathrm{Si}_{2} \mathrm{O}_{8}\) (d) \(\mathrm{K}_{2} \mathrm{Al}_{2} \mathrm{Si}_{2} \mathrm{O}_{8} \cdot \mathrm{xH}_{2} \mathrm{O}\)

Short answer

The chemical formula of zeolite is option (a): \(\mathrm{Na}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\cdot \mathrm{xH}_{2}\mathrm{O}\).

Step-by-step solution

Identify Zeolite Composition

Zeolites are a group of minerals, typically microporous, aluminosilicate solids. They usually consist of silicon, aluminum, and oxygen, with alkali or alkaline earth metals such as sodium and potassium.

Analyze Given Options

Look at each option's composition: 1. Option (a) is \(\mathrm{Na}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\cdot \mathrm{xH}_{2}\mathrm{O}\)2. Option (b) is \(\mathrm{Na}_{2}(\mathrm{Na}_{4}(\mathrm{PO}_{3})_{6})\)3. Option (c) is \(\mathrm{Ca}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\)4. Option (d) is \(\mathrm{K}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\cdot \mathrm{xH}_{2}\mathrm{O}\)

Match Zeolite's Specific Formula

Zeolites commonly have the formula \(\mathrm{Na}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\cdot \mathrm{xH}_{2}\mathrm{O}\), where water molecules \(\mathrm{xH}_{2}\mathrm{O}\) are apparent and it generally involves sodium \(\mathrm{Na}\).

Select the Correct Option

Comparing the known zeolite formula with the options, the answer is option (a): \(\mathrm{Na}_{2}\mathrm{Al}_{2}\mathrm{Si}_{2}\mathrm{O}_{8}\cdot \mathrm{xH}_{2}\mathrm{O}\), as it matches the typical composition of zeolites.

Key concepts

Aluminosilicate Minerals

Aluminosilicate minerals are an important group of minerals that contain aluminum, silicon, and oxygen. These minerals are the backbone of the zeolite family, forming intricate structures with their interlinked tetrahedral frameworks.

In these frameworks, aluminum and silicon atoms are surrounded by oxygen, creating a three-dimensional lattice. This configuration gives them unique properties, like high thermal stability and chemical resistance.

• These minerals are commonly found in Earth's crust, especially in volcanic rocks and sediments.
• They serve important roles in various applications, from catalysis to water purification, due to their porous nature.

Understanding how aluminosilicate minerals form and interact is crucial in fields like geology, chemistry, and environmental science.

Microporous Solids

Microporous solids are materials characterized by their incredibly small pores. These pores usually measure less than 2 nanometers in diameter, offering a high surface area relative to their volume. The small size of these pores makes these solids extremely useful in selective adsorption processes.

In the context of zeolites, the microporous nature allows these materials to act as molecular sieves:

• They can selectively absorb molecules of specific sizes while excluding others, making them useful in separating mixtures based on size exclusion.
• This property is beneficial in environmental applications, where pollutants can be captured and removed from air or water.

Microporous solids like zeolites are invaluable in various industries, including oil refining, wastewater treatment, and gas purification.

Alkali Metals

Alkali metals are a group of chemical elements found in Group 1 of the periodic table. These include sodium (Na), potassium (K), and others, all of which have their own unique traits.

In zeolites, alkali metals serve as cations. They balance the negative charge created by the aluminosilicate framework:

• For instance, sodium and potassium can be frequently found within zeolite structures.
• These metals facilitate ion exchange processes, which is useful for applications like water softening and molecular sieving.

The functionality and efficiency of zeolites in these applications greatly depend on the presence of these alkali metals and their ability to interact with other molecules in the structure.