What is Silica?
Silica is a compound made up of silicon and oxygen, the two most prevalent elements found on earth's crust. Silica is often found in crystalline form and relatively rarely in amorphous form. It has the chemical formula SiO2 as it comprises one silicon atom and two oxygen atoms. One of the Silica examples is a mineral found in quartz. It is a chemical substance that makes up the majority of the Earth's rocks. Silica may be found in five crystalline forms (quartz, coesite, and stishovite), as well as a cryptocrystalline form (chalcedony) and an amorphous form (amorphous Silica) (opal).
Since 5000 years BC, the early industrial applications of crystalline Silica were most likely tied to metallurgical and glass-making activity. It has aided human advancement throughout history, serving as a critical raw element in the world's industrial growth, particularly in the glass, foundry, and ceramics sectors. Silica is utilized in the plastics of mouses used for computers and provides all raw materials for silicon chips, contributing to today's information technology revolution.
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Occurrence of Silica
Once you know Silica examples, it is vital to understand the occurrence of the same. Silica comes in nine crystalline forms or polymorphs, with quartz being the most prevalent, tridymite, and cristobalite being the others. It can also be found in cryptocrystalline forms. Chalcedony is a fibrous type of quartz that includes semi-precious stone varieties, including agate, onyx, and carnelian.
The second most abundant mineral in the earth's crust is quartz. It can be found in all three forms of rock on the planet: igneous, metamorphic, and sedimentary. Because it is exceedingly resistant to physical and chemical disintegration by the weathering process, it is widespread in sedimentary rocks.
Silica is a critical component in industrial minerals. Silica is used in abrasives and polishes, glass manufacture, fillers, and other areas, silica brick manufacturing as a catalyst, ceramics, electronics, and optics. For industrial purposes, Silica formula (SiO2) is used to produce silicon dioxide.
There are various uses of silica dioxide including-
Used in concrete for building sector
Utilized in hydraulic fracturing in its crystalline form.
It's a material used for making glass.
As a sedative
Used in the manufacture of elemental silicon.
Types of Silica
There are different types of Silica used in industries. Colloidal Silica is primarily employed in silicon wafers, polishing, and precipitated Silica as a high-temperature binder.
Fused Silica, another type, happens when the fusing of very high-quality silica sand feedstock in electric arc and resistance furnaces. This Silica that has been transformed can be utilized as filler or an electronic encapsulate.
As amorphous Silica, high-purity ground silica is made from silica sand or soft friable rocks. Specialty plastics, electronics abrasives, and optics are among its most common applications.
What is Silica Gel?
One standard answer to what is silica gel is it is a type of synthetic amorphous Silica made up of a dense network of colloidal silica particles. It has a surface area of between 300 and 850 m2/g. Pore sizes in the range of 22–150 are the most common. Silica gel is made by reacting a sodium silicate solution with a mineral acid, such as sulfuric acid, to generate a concentrated dispersion of finely split hydrated SiO2 particles, polymerizing to form the silica gel.
What is Silica Sand?
Silica sand is a widely used kind of sand on the planet. It may be used for a variety of purposes. Sand is a broad name for broken down granules of minerals or rocks that are technically between one-sixteenth and two millimeters in diameter and fall between silt and gravel on the size scale.
Difference Between Silica and Silicon
Inorganic chemistry frequently uses the phrases silicon and Silica. Second, to oxygen, silicon is the most abundant element on the planet. As a result, understanding the differences between silicon and Silica is critical. Silicon acts as the element, whereas Silica acts as the compound.
Composition
Silicon is a single ingredient in its composition.
Silica is a mineral made up of silicon and oxygen atoms.
Melting Point
Silicon Melting Point: Silicon has a melting point of 14140°C.
Silica has a melting point of 17130 degrees Celsius.
Uses of Silica
The application of silica is majorly in industry. Glass, construction, ceramics, and the chemical sector are the most prominent users of silica. Silica sand is utilized in water purification and agriculture, and silica sand is used as functional filler for paints, and rubber.
The industrial purpose of silica is huge, but this usage is also affecting the health of the human body in larger ways.
FAQs on Silica
1. What is silica and what is its chemical formula?
Silica is the common name for the chemical compound silicon dioxide, which has the chemical formula SiO₂. It is a major component of the Earth's crust and exists in various forms, most commonly as quartz. It is a hard, unreactive, and typically colourless or white crystalline solid.
2. What are the main uses of silica in daily life and industry?
Silica has a wide range of applications due to its physical and chemical properties. Key uses include:
- Glassmaking: It is the primary component of most common types of glass.
- Construction: Sand, which is largely quartz (silica), is a fundamental ingredient in concrete and mortar.
- Electronics: High-purity silica is used to manufacture silicon wafers for semiconductors.
- As a Desiccant: Silica gel, an amorphous form, is widely used to absorb moisture and keep products dry.
- Fillers: It is used as a functional filler in paints, plastics, and rubber to improve strength and durability.
3. What are the different types of silica?
Silica is broadly classified into two main types based on its atomic structure:
- Crystalline Silica: Atoms are arranged in a fixed, repeating pattern. Common examples include quartz, cristobalite, and tridymite. Quartz is the most abundant form.
- Amorphous Silica: Atoms lack a long-range ordered structure. Examples include silica gel, fumed silica, and naturally occurring diatomaceous earth.
4. Why does silica (SiO₂) have a very high melting point and exist as a solid, while carbon dioxide (CO₂) is a gas?
This difference is due to their chemical structures. Silica (SiO₂) forms a giant covalent network structure, where each silicon atom is bonded to four oxygen atoms in a strong, three-dimensional lattice. Breaking these strong covalent bonds requires a large amount of energy, resulting in a high melting point. In contrast, carbon dioxide (CO₂) consists of simple, discrete molecules with weak intermolecular forces (van der Waals forces) between them. These weak forces are easily overcome, which is why CO₂ is a gas at room temperature.
5. What is the acidic nature of silica?
Silica (SiO₂) is an acidic oxide. Although it is insoluble in water and does not react with most acids, it does react with strong bases and alkalis. For example, it reacts with hot, concentrated sodium hydroxide (NaOH) to form sodium silicate (Na₂SiO₃), a key reaction in the production of 'water glass'. It is also notably attacked by hydrofluoric acid (HF).
6. How do the structures of crystalline quartz and amorphous silica gel lead to their different uses?
The difference in their atomic arrangement is key to their applications:
- Crystalline Quartz: Its strong, rigid, and ordered tetrahedral network structure makes it very hard and gives it piezoelectric properties. This makes it ideal for use in watches, clocks, and radio transmitters.
- Amorphous Silica Gel: Its disordered structure is highly porous with a vast internal surface area. This property makes it an excellent adsorbent, which is why it is used as a desiccant (to absorb moisture) and in chromatography (to separate chemical mixtures).
7. Is crystalline silica considered hazardous to humans?
Yes, long-term inhalation of fine airborne particles of crystalline silica can be hazardous to human health, potentially causing a lung disease called silicosis. This is primarily an occupational hazard in industries like mining, quarrying, and construction. In contrast, amorphous silica, such as the silica gel found in consumer product packaging, is generally considered non-toxic.
