Question

Glass and cement are two important examples of (a) man-made silicates (b) silicones (c) zeolites (d) organic polymers.

Short answer

Glass and cement are (a) man-made silicates.

Step-by-step solution

Identify the Composition of Glass and Cement

Determine what glass and cement are primarily made of to classify them correctly among the given options.

Understand the Definitions

Research and understand the definitions of each of the provided options: man-made silicates, silicones, zeolites, and organic polymers.

Select the Correct Answer

Match the primary composition of glass and cement with the appropriate option that defines their composition.

Key concepts

Composition of Glass

Understanding the composition of glass is essential for recognizing its classification as a man-made silicate. Glass is primarily made from silica (silicon dioxide, or SiO2), which is derived from sand. In addition to silica, glass typically contains other materials such as sodium carbonate (soda) and calcium oxide (lime) that act as fluxes to lower the melting temperature and stabilize the structure. For instance, the common form of glass, known as soda-lime glass, is composed of approximately 70-75% silica, 12-16% soda, and 5-10% lime.

The process of glassmaking involves melting these raw materials at high temperatures and then rapidly cooling them, which prevents the formation of crystals and results in an amorphous or non-crystalline solid. This unique structure is what gives glass its characteristic properties like transparency, brittleness, and resistance to chemical action.

Enhancements and variations in properties can arise when additional components such as boron oxide, aluminum oxide, or silicon carbide are added during the manufacturing process, resulting in different types of glass with specialized applications.

Cement Chemistry

Cement chemistry is a complex field that delves into the chemical and physical properties of materials used to create cement, a critical component in concrete production. Cement primarily consists of a mixture of calcium silicates, calcium aluminates, and calcium aluminoferrite. The process of making cement involves the extraction and blending of raw materials like limestone (calcium carbonate), clay (aluminum silicates), and other materials which are then heated to form a clinker. The clinker is mixed with gypsum and ground to a fine powder, known as Portland cement.

A closer look at the chemistry reveals the principal compounds in cement, which include tricalcium silicate (\( Ca_3SiO_5 \)), dicalcium silicate (\( Ca_2SiO_4 \)), tricalcium aluminate (\( Ca_3Al_2O_6 \)), and tetracalcium aluminoferrite (\( Ca_4Al_2Fe_2O_10 \)). The hydration of these compounds when mixed with water is what imparts strength and durability to set concrete. Understanding the precise chemistry of cement can lead to enhancements such as improved strength, faster setting times, and resilience to environmental factors.

Classification of Materials

The classification of materials is a fundamental topic in science and engineering, helping us to categorize substances based on their properties and potential uses. Materials can generally be classified into categories such as metals, ceramics, polymers, composites, and semiconductors. Each class possesses a unique set of characteristics. For instance, metals are typically strong, malleable, and good conductors of electricity. Ceramics include nonmetallic, inorganic solids such as glass and cement, often characterized by high hardness, brittleness, and heat resistance.

Polymers are large molecules made up of repeating units, known for their flexibility and low density. Composites are engineered materials made from two or more constituent materials with significantly different physical or chemical properties, designed to provide a combination of the best attributes of each. Semiconductors, the building blocks of electronic devices, have electrical properties that are intermediate between metals and insulators.

Understanding the classification of materials is crucial when selecting the right material for a specific application or for improving existing materials for new technological advancements.