Chemistry
■ Chemistry and its Branches
■ Matter
■ Behavior of Gases
■ Atoms and Molecules
■ Structure of an Atom
■ Periodic Table
■ Chemical Bonding
■ Types of Reactions
■ Elements
■ Metals, Non Metals and Metallurgy
■ Properties of Compounds
■ Acids, Bases and Salts
■ Solutions
■ Water
■ Organic Chemistry
■ Fuels
■ Biochemistry
■ Nuclear Chemistry
■ Chemical Processes
■ Chemistry in Daily Life
Cleansing Agents - Soaps and Detergents
Soaps and Detergents are the commonly used Cleansing Agents. Something that cleans dirty surfaces is called a detergent. One kind of detergent is soap. However, the term "detergent" typically only refers to synthetic detergents, which differ chemically from soap. Soap and detergent products are produced in the form of bars, flakes, granules, liquids and tablets. People use soap to wash their bodies. They shampoo their hair with soaps and detergents. Daily bathing with soap prevents dirt and natural body oils from clogging the pores of the skin.
Types of Cleansing Agents
1. Soaps
With the discovery of methods to produce potassium hydroxide in the 18th century and sodium hydroxide in the 19th century, soap making became a big industry. Sodium hydroxide is utilised in washing soap and potassium hydroxide in toilet soap. Soap is made by reacting coconut oil or other oils or fats with alkalis like sodium hydroxide. Saponification is the process of making soaps. Soaps are sodium or potassium salts of long-chain fatty acids (e.g. oleic, stearic, palmitic). Potassium hydroxide is used to make soft soaps. Clear soaps are made by dissolving soap in ethanol and evaporating the excess solvent. Soap is used to wash clothes because it reduces the surface tension of water. The process of adding NaCl to the solution for the separation of soap from glycerol is called 'Salting out'.
2. Synthetic Detergents
The search for a substance with better cleaning power than soaps led to the development of detergents. The chemical name of detergents are Alkyl Benzene Sulfonates. Synthetic detergents are a mixture of sodium salts of aromatic and aliphatic sulphonic acids. Synthetic detergents are cleaning aids that do not contain soap but have all the properties of soap. They dissolve in hard water and normal water. They are mainly classified into three categories - Anionic, Cationic and Non-ionic or neutral Detergents.
Anionic Detergents - Anionic detergents are mostly used for household purposes. They are also used in toothpastes. In these, the anion part of the molecule is involved in cleaning activities.
Cationic Detergents - Cationic detergents have limited uses due to their high cost and disinfectant properties. They are used in hair conditioners.
Non-ionic or neutral Detergents - Liquid detergents used for washing bowls are examples of these. There are no ions in their structure.
3. Natural Cleansing Agents
It consists of a chemical called saponin which produce lather when it is shaken with water. Soap nuts, soap pods, turmeric powder, milk, honey, coconut oil, lemon, curd, cucumber etc are examples of naturally obtained cleansing agents.
Polymers
Polymer is a large, long, chainlike molecule formed by the chemical linking of many smaller molecules. The small molecular building units are called monomers. Monomers are joined into chains by a process of repeated linking known as polymerization. A polymer may consist of thousands of monomers. Some polymers occur naturally. Others are synthetic. Many common and useful substances are polymers. For example, starch and wool are naturally occuring polymers. Starch is formed by plants from a simple sugar called glucose and wool is a variety of protein. Other examples of natural polymers are cellulose and silk. Proteins, DNA, Starch and Cellulose are the polymers found in living organisms and they are called Biopolymers. Nylon and polyethylene, a tough plastic material are synthetic polymers. Rayon, Teflon, Orlon, Polyester etc are other examples for man made polymers or synthetic polymers. Rayon is known as artificial silk and is used in carpets, tyre code, surgical dressings, fabrics etc. Teflon is a polymer used to coat the inside of nonstick kitchenware. The monomer of teflon is Tetrofluoroethylene. Rubber, another polymer, occurs naturally and is also made synthetically. The basic nature of Fiber, Plastic and Rubber is Polymer. Fibers are polymers suitable for making strong yarns. Whereas, Plastics are polymers that can be molded into various shapes and Rubber is a polymer that has elastic properties.
Polymerization
Polymerization is a chemical process important in the production of plastics, artificial fibres, synthetic rubber and paints. In this process, many small molecules called monomers combine to build much larger molecules called polymers. The process is known as homopolymerization if only one type of monomer is utilized. Copolymerization is the process of using many types of monomers. The solid plastic known as vinyl, or polyvinyl chloride, is created when the gas vinyl chloride is homopolymerized. The plastic used to wrap food is made by copolymerizing vinyl chloride with vinylidene chloride. Chemists also classify polymerization processes by the chemical reactions that occur.
Polymers and Monomers
1. Polyvinyl Chloride (PVC) - Vinyl Chloride
2. Polyvinyl Acetate (PVA) - Vinyl Acetate
3. Polythene - Ethene
4. Bakelite - Phenol and Formaldehyde
5. Polystyrene - Styrene
Types of Polymers
There are three types of polymers, namely, natural, semi-synthetic and synthetic polymers.
I. Natural Polymers
Both plants and animals contain them naturally. For instance, starch, cellulose, silk, rubber and wool. In addition, we have biopolymers, which are biodegradable polymers. Proteins, DNA, starch and cellulose are Biopolymers.
1. Starch
Starch is formed by plants from a simple sugar called glucose.
2. Cellulose
Cellulose is a substance that forms a major part of the cell walls of trees, grasses, vegetables and many other plants. Cellulose is a carbohydrate-that is, a substance composed of carbon, hydrogen and oxygen. All fruits and vegetables contain cellulose. Cellulose makes up an important part of many family products. Industries use strong acids and alkalis to modify the properties of cellulose for various purposes. For example, textile manufacturers strengthen cotton fibers by treating with an alkaline solution such as caustic soda.
3. Silk
Silk is a strong, shiny fibre that is used to make cloth. Silk has a natural beauty that few other fibres can equal and is often called the queen of fibres. Silk fibre is made from the cocoons of caterpillars called silkworms. Many other animals, including spiders and lacewings, spin silk threads. But their silk cannot economically be made into cloth. Silk is the strongest of all natural fibres. A thread of silk is stronger than the same size thread of some kinds of steel. Silk is highly elastic. It can be stretched and will still return to its original shape. Silk garments are extremely light in weight and are warmer than cotton, linen or rayon clothing. Dyed silk cloth has a deeper, richer appearence than most other dyed fabrics. Silk can be ironed easily and it resists wrinkling.
4. Wool
Wool is a fibre that comes from the fleece of sheep and some other animals. It is made into durable fabrics used in manufacturing blankets, clothing, rugs and other items. Wool fabrics clean easily and they resist wrinkles and hold their shape well. Wool also absorbs moisture and insulates against cold. All these features make wool popular for coats, sweaters, gloves, socks and other clothing. Wool fibres are nearly cylindrical in shape. Overlapping scales on the surface make the fibres mat and interlock under heat, moisture and pressure. This property of wool fibres is called felting. Felting increases the strength and durability of wool fabrics. It also enables wool to be made into felt.
II. Semi-synthetic Polymers
They undergo additional chemical alteration after being produced from naturally existing polymers. For example, cellulose derivatives like cellulose nitrate and cellulose acetate. Manufacturers produce substances called cellulose derivatives by combining cellulose with certain chemicals. The most widely used cellulose derivate is cellulose acetate. Other derivatives include carboxy methyl cellulose and cellulose nitrate. In the late 1940's, synthetic polymers prepared mainly from petroleum began to replace cellulose in some plastic, fibers and some photographic film. But some experts believe that a petroleum shortage and rising oil prices will probably lead to greater use of cellulose.
III. Synthetic Polymers
These polymers were created by humans. The most popular and extensively utilized synthetic polymer is plastic. It is utilized in many dairy products and industries. Other examples are Polyethylene, Rayon, Teflon, Orlon, Polyester, Polyether, Nylon-66, Nylon-6 etc.
1. Polyethylene
Polyethylene or polythene is the most commonly used plastic. It is a polymer, mainly used for packaging products like plastic bags, geomembranes, plastic films, and containers including jars, bottles, cups etc.
2. Rayon
Rayon is a manufactured fibre produced from wood pulp or cotton linens. It is widely used to make industrial materials and knit and woven textiles for clothing, upholstery, draperies and decorating fabrics.
3. Teflon
Teflon is the trade name for polytetra fluroethylene, which was discovered in 1938 by American chemist Roy.J.Plunkett. Plunkett discovered the material accidently while working to develop a non toxic refrigerant from gaseous tetrafluroethylene. Instead, he came up with a waxy white powder that indicated that the molecules had polymerized or combined with each other. Plunkett went on to develop a method for producing the powder commercially. Teflon was first used to manufacture gaskets and valves needed in the development of the atomic bomb. The first Teflon coated muffin tins and frying pans were sold in 1960. Teflon is now used for artificial corneas, substitute bones for chin, nose, hip and knee joints and other anatomical parts. Non stick kitchenware are coated with teflon and potassium hydrogen tartarate. It is anti-corrosive.
4. Orlon
Orlon is also known as polyacrylonitrile. It is mainly used in the garment industry. It is a high resistive fibre to sunlight and greenhouse gas.
5. Polyester
Polyester is the general name for any of a group of widely used synthetic products. Polyesters are strong, tough materials that are manufactured in a variety of colours, shapes and sizes.
6. Polyether
Polyethers are polymers consisting of monomers joined together by ether linkages. A variety of polyethers are manufactured ranging from elastomers to the engineering plastics.
7. Nylon-66
Nylon-66 is a synthetic fibre belonging to polyamide. Nylon-66 is prepared from hexa methylene diamine and adipic acid.
8. Nylon-6
Nylon-6 is a synthetic fibre belonging to polyamide. It exhibits highly tensile strength, better impact resistance and good abrasion resistance.
Plastics
Plastics is invented by Alexander Parkes in 1856. Plastics are synthetic polymers which can be easily moulded or set into a desired shape. They rank among the most practical materials ever made. Plastic goods are used in our homes, workplaces, and educational institutions. Plastics that are as soft as cotton or as rigid as steel have been created by engineers. Engineers can create plastics that are any colour of the rainbow or as clear and colourless as crystal. Plastics can be hard or rubbery, and they can be molded into a vast array of items, such as soft fabrics, squeezable bottles, and vehicle fenders. Products made of plastic, particularly those utilized by industries, may last for many years. Plastics consist of long chains of molecules called polymers. Small molecules in repeating patterns make up these chains. A 'link' is created in the chain of the polymer by each of the smaller molecules. The chains in certain plastics are rigid and arranged like logs in a river. In others, they resemble spaghetti on a plate, tangled and stretchy. The most remarkable feature of plastics is their shapeability, which is a result of many architectures. The Greek word plastikos, which meaning "able to be shaped," is actually where the word "plastics" originates. The word 'plastic' was originally used in a patent for a mold in 1862. The first artificial plastic created is Bakelite. Bakelite is invented by Leo Hendrik Baekeland in 1907. It is made from phenol and formaldehyde. Microns are the unit used to express the thickness of plastics. 1 micron is equal to 0.000001 m.
Chloroform is a liquid that dissolves plastic. Burning plastic releases a variety of toxic gases into the atmosphere, that includes carbon monoxide, dioxins, furans and polychlorinated biphenyls. Dioxins can become a reason for cancer. Disposal of Dioxin is difficult, because it does not readily degrade in soil or water. Melamine formaldehyde Resins, noryl, carbon fibre reinforced plastic, acrylate etc. are examples of commonly used plastics. Melamine Formaldehyde Resins are used for making unbreakable plastic containers. Noryl is a plastic with the properties of metal. Carbon fibre reinforced plastic is a plastic used to make aircraft, nuclear reactors and sports equipment. Acrylate is a plastic used to make artificial teeth and lenses.
Types of Plastics
Thermoplastics and Thermosetting plastics are the two types of Plastics. They are explained as follows.
1. Thermoplastics
Thermoplastics are plastics that soften when heated and harden when cooled. Polythene, Nylon, Poly Vinyl Chloride (PVC), polypropylene, polystyrene, acrylic, teflon etc. are examples for Thermoplastics.
i. Polythene
Polythene, also known as polyethylene or polyethene, is the most commonly used plastic material derived from ethylene monomers. It is a versatile polymer, mainly used for making packets, bags, tubes, electrical insulation and containers including jars, bottles, cups etc. About a third of all synthetic products are polyethylenes. There are three main types of polyethylene: high density polyethylene (HDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). HDPE is the toughest and most rigid type. It is used to make bottles and jugs. LDPE and LLDPE are relatively soft and flexible. Manufacturers produce them as thin films. LDPE is used to make bread bags and LLDPE is used to make Garbage bags.
ii. Nylon
Nylon is a fibre entirely made from chemicals. It is stronger than silk. Nylon is resistant to grease and dirt. It was used in a multitude of applications, ranging from parachutes to stockings.
iii. Poly Vinyl Chloride (PVC)
Poly Vinyl Chloride (PVC) is a thermoplastic, much stronger than polyethylene. It is used for the manufacture of electrical insulators, water proof cloth, plumbing, shoes, hand bags, raincoats, boats, bottles, furnitures etc. Poly Vinyl Chloride (PVC) is the polymer of Vinyl Chloride. Dioxin is a toxic gas that results from burning PVC.
iv. Teflon
Teflon is a polymer named Polytetrafluoroethylene (PTFE). Non stick kitchenware are coated with teflon and potassium hydrogen tartarate. It is anti-corrosive.
2. Thermosetting Plastics
Thermosetting Plastics are plastics that remain soft when heated and permanently harden when cooled. Once hardened, thermosetting plastics cannot be reshaped by heating. Polyester, Bakelite, Epoxy, Phenolic, Melamine, Polyurethane etc. are examples for Thermosetting plastics.
i. Polyester
Polyesters are strong, tough polymer that are made in a variety of colours, shapes and sizes. They are made from chemical substances found mainly in petroleum. Polyesters are manufactured in three basic forms - fibres, films and plastics. Polyester fibres are widely used in carpets, clothing and upholstery. Polyester films are made into magnetic tapes for use in computers and tape recorders. Others serves as insulation for electrical wires or as containers. Thin polyester films provide airtight seals on containers and packages.
ii. Bakelite
About 50 years after the introduction of celluloid, the Beligian born chemist Leo Baekeland discovered in 1909 a new substance while experimenting with formaldehyde. Upon heating it become soft, after which it could be moulded and then hardened; it could also be made in powdered form, set under pressure, and heated to form a hard solid material. Nonconductive and resistant to heat and corrosion. It was named Bakelite, the first synthetic plastic. Many products were made from it, so it can be said to have triggered the start of the plastics industry. It is used to make electrical insulators and building materials.
iii. Melamine
Melamine is a fire-resistant plastic. Firefighters' uniforms are made from melamine plastic.
iv. Polyurethane
Polyurethane foam is used for thermal insulation, sound proofing and padding. Polyurethanes are polymers in which formation of a urethane group is an important part of the polymerization process.
Rubber
Rubber is one of the most important raw materials used today. It is a naturally available elastic polymer. Ordinary rubber is a thermoplastic substance. Rubber is especially useful for several reasons. It does not easily conduct electricity and retains air and moisture. However, the fact that it is elastic is what matters most to us. A rubber band's elasticity allows it to rapidly return to its original shape after being stretched. A rubber ball bounces because of this same springiness. The rubber heels absorb shock while walking because they have elasticity. We depend so much on rubber that it would be almost impossible to get along without it. This is not the case with most other materials. Rubber dissolves in Benzene.
Types of Rubber
Rubber is broadly classified into three as natural rubber, synthetic rubber and vulcanized rubber.
1. Natural rubber
Natural rubber comes from the juice of a tree. It is derived from the latex of rubber trees. Polyisoprene, an elastomer is an example for Natural Rubber. Natural Rubber is known for its elasticity, flexibility, and high tensile strength.
2. Synthetic rubber
Synthetic rubber is made from chemical polymerization and other manufacturing processes. It is a man made polymer produced from petrochemicals. The first synthetic rubber is Neoprene. Buna Rubber, Styrene Butadiene Rubber (SBR), Butyl Rubber and Thiokol are examples of synthetic rubber.
i. Neoprene Rubber
The main properties of Neoprene Rubber are not easily flammable, does not easily reacts with oils and solvents and stable at high temperature. Its main uses is in the manufacture of cable insulation, conveyor belt in coal mines, making hose etc.
ii. Buna Rubber
Buna Rubber is a synthetic rubber with a variety of uses. The two types of Buna Rubber are Buna-S (Styrene-Butadiene Rubber) and Buna-N (Nitrile Rubber). Tires and soles are made from Buna-S, whereas oil seals and gloves are made from Buna-N.
iii. Styrene Butadiene Rubber (SBR)
High frictional force, not easily broken, resists ozone and gets easily oxidised are the properties of Styrene Butadiene Rubber (SBR). Tyres and Foot wears are made from Styrene Butadiene Rubber.
iv. Butyl Rubber
Butyl Rubber has high air impermeability and is used in tire inner tubes and other sealing applications.
v. Thiokol
High elasticity, hardness, doesn't dissolve in organic solvents are the properties of Thiokol. It is used in the manufacture of tanks for storing solvents, making seal and making hoses.
3. Vulcanized Rubber
In 1770, the English chemist Joseph Priestly discovered the substance would rub out pencil marks and named it rubber. It was a sticky material until in 1839 when the American inventor Charles Goodyear accidentally dropped a mixture of sulphur and rubber on a hot stove and found that it was soft and pliable even when cold. The process of heating rubber with sulphur for the betterment of its properties is called vulcanisation. Vulcanisation enhances the following properties of rubber: tensile strength, hardness, elasticity, ability to withstand heat changes. These properties can be varied by changing the quantity of sulphur, temperature and time taken for vulcanisation. Goodyear's discovery began the rubber industry, including the manufacture of rubber tyres. Thomas Hancock got the patent for the invention of vulcanisation.
Rubber Tyre - Although the discovery of vulcanized rubber took place in 1839, it was not until 1887 that the Scottish born inventor John B.Dunlop made his first pneumatic tyre for a biycle. Tyres filled with air are called pneumatic. By 1890 the pneumatic tyre business was in full swing in Ireland. In time the tyres were made for automobiles also. Tubeless tyres and modern materials have greatly improved tyre performance in recent years.
Fibres
A fiber is a strand of a material that resembles hair and is incredibly long compared to its breadth. A fiber's length is at least 100 times its width. Because of their flexibility, fibers can be spun into yarn and used to create textiles. The smallest visible component of any textile product is called a fiber. Manufacturers use fibres in clothing and in such home furnishing as carpets, curtains and upholstery. They also use fibres in many industrial products, including parachutes, fire hoses, insulation and space suits. In medicine, fibres are used to make artificial arteries and tendons. Polycotton is the fabric made from a mixture of cotton and polyester and Polywool is the fabric made from a mixture of polyester and wool fibers.
Types of Fibers:
I. Natural Fibers
These are derived from plants or animals, such as cotton, jute, wool, and silk.
1. Cotton
Cotton is a soft white fibrous substance that surrounds the seeds of a cotton plant. It is used to make textile fibre and thread for sewing. It is the widely produced natural fiber on the planet. Cotton is popularly called as universal fibre.
2. Jute
Jute is a long, soft, shiny fibre that can be spun into coarse, strong threads. It is one of the cheapest natural fibres and is second only to cotton in amount produced and variey of uses.
3. Wool
Wool is a fibre that comes from the fleece of sheep and some other animals. It is made into durable fabrics used in manufacturing blankets, clothing, rugs and other items.
4. Silk
Silk is a strong, shiny fibre that is used to make cloth. Silk has a natural beauty that few other fibres can equal and is often called the queen of fibres. Silk fibre is made from the cocoons of caterpillars called silkworms.
II. Synthetic Fibers
These are man-made fibers, often produced from petrochemicals, like nylon, rayon, polyester, terylene and acrylic.
1. Nylon
Nylon is a fibre entirely made from chemical processes. It is much stronger than the natural fibre like silk. Nylon is resistant to grease and dirt. Its applications includes the manufacture of parachutes, ropes, stockings etc. Nylon is the first artificial fibre made by humans.
2. Rayon
Rayon is also called as artificial silk. Man made materials in the textile world prior to 1935 were really chemically treated natural products like Rayon. Rayon is a synthetic fibre made from wood pulp or cotton linens. It is widely used for knit and woven textiles for clothing, upholstery, draperies and decorating fabrics.
3. Polyester
Polyesters are manufactured in three basic forms - fibres, films and plastics. Polyester fibres are used to make easy to care for fabrics, which resist fading, wrinkling and mildew. Polyester fibres are also used as the tough cord fabric in tyres. Thin polyester films provide airtight seals on containers and packages.
4. Terylene
Terylene is a synthetic polyester fiber manufactured from polyethylene terephthalate (PET). It is widely used in the textile industry for clothing and other applications.
5. Acrylic
Acrylic is a synthetic fiber made from polyacrylonitrile. It is widely used in clothing, home furnishings and other applications. The example of acrylic fiber is Orlon.
III. Optical Fibers
These are thin strands of glass or plastic that transmit light, used for high-speed communication.
Cement
Cement is a complex mixture of aluminates and silicates of calcium. In 1824, a British Engineer, Joseph Aspidin made a binding material by mixing lime and silica and firstly it was named as 'portland cement'. The setting of cement is due to the hydration of calcium silicates and calcium aluminates. The mixture of cement, silica and water is called cement mortar. Concrete is reinforced by embedding steel in cement. A suitable site of a cement plant requires proximity to limestone and gypsum.
How is cement manufactured?
The raw materials (calcium carbonate, silica, alumina and iron ore) are ground into a fine powder and mixed in the fixed proportion. This is heated in a furnace at a high temperature (1500°C). Clinkers, which is a complex mixture of calcium silicate and calcium aluminate is formed. Gypsum is added to clinker and the mixture is powdered to make cement.
Cement and Concrete
Cement and Concrete are among the most important building materials. Cement is a fine, grey powder. To form concrete, it is mixed with water and other ingredients like crushed stone, sand, and gravel. As the concrete hardens, the cement and water combine to produce a paste that holds the other ingredients together. Concrete is easy to make, reasonably priced, waterproof, and fireproof. Nearly all the cements used today is portland cement, which is a Hydraulic cement or one that hardens under water. Portland cement is used chiefly to make concrete. Cement and concrete are used to make most of foundations for sky scrapers and big houses. Lime, Silicon, Aluminium, Magnesia, Iron oxide, Calcium Sulphate, Sulphur Trioxide and Alkaline are the chemical composition of cement.
Types of Cement
Cement is mainly classified into two types depending on the hardening and setting mechanism. These are Hydraulic Cement and Non-hydraulic Cement. Depending on the composition and characteristics, cement is classified into several types.
Alcohols
Alcohols are compound which contain one or more hydroxyl groups. Proof is the unit of measuring the purity of alcohol. Lucas test and Victor meyer test are related with Alcohols. Alcohols are classified as primary, secondary and tertiary alcohols. The classification is done in accordance with the carbon atom is bonded to the hydroxyl group. For primary alcohols (1°), carbon atom is bonded to only one other carbon atom, for secondary alcohols (2°), carbon atom is bonded to two other carbon atom and for tertiary alcohols (3°), carbon atom is bonded to three other carbon atom. Most of the alcohols are colourless liquids or even behave as solid at room temperatures. There are several kinds of commercially important alcohols. They are as follows.
1. Ethyl Alcohol (Ethanol)
Ethyl Alcohol (C2H5OH) is drunk in liquids. Ethyl Alcohol is also called as Grain Alcohol. Ethanol is used in the preparation of various beverages. The grape spirit is a continuous boiling mixture of ethanol and water. The percentage of alcohol in spirit is 95%. The most alcoholic beverage is whiskey. Whiskey is made from barley. The least alcoholic beverage is beer. Brandy is made from grapes. Russia is the birthplace of vodka.
2. Methyl Alcohol (Methanol)
Methyl Alcohol (CH3OH) is used in such products as antifreeze or solvents. Methanol is a type of alcohol used for many industrial purposes. It is also called Methyl Alcohol or wood alcohol. Methanol is a clear, colourless organic compound, is flammable and highly poisonous. Drinking it, or inhaling its fumes for prolonged periods, can cause blindness or even death. It is also harmful to the skin. It has a molecular weight of 32.04. It boils at 65°C and freeze at -94°C. At 20°C, its density is 0.7915 grams per cubic centimetre. Methanol mixes readily with water and with such organic compounds as benzene and ether. Some of these mixtures are used in motor vehicles as antifreezes for windshield washer fluids and fuel lines. Such mixtures lower the temperature at which ice forms. Methanol is an alcohol used as a solvent in paint manufacturing and in the manufacture of varnishes and formalin. Hydrogen is a gas that is added with carbon monoxide in the industrial production of methanol.
3. Ethylene Glycol
Ethylene glycol is used as automotive antifreeze, ingredient in hydraulic fluids and in the manufacturing of plastics, paint solvents and printing inks. It is also used as a chemical reagent in the manufacture of alkyd resins, polyesters, synthetic waxes and explosives.
4. Isopropyl alcohol
It is manufactured by indirect hydration of propylene. It is most commonly used as an industrial solvent and as a rubbing alcohol applied to the skin.
5. Glycerol
Glycerol, often known as glycerine, is a sweet, syrupy material that contains three alcohol hydroxyl groups. Glycerol was first made as a by-product of soap manufacture, through the process of saponification of fats.
Other Alcohols
1. Rectified Spirit and Methylated Spirit
Mixture of Ethyl Alcohol (95.87%) and water (4.13%) is known as rectified spirit. Ethyl Alcohol containing 5 to 10% methyl alcohol is called methylated spirit (denatured spirit).
2. Absolute Alcohol
99.5% ethanol is called absolute alcohol. The mixture of petrol and absolute alcohol is called as power alcohol.
Glasses
Glass is a super cooled liquid. The major ingredients of glass are sand, lime and soda ash. Borax increases the hardness and refractory character of glass. Glass dissolves in Hydrofluoric acid. Glass is a mixture of silicates. Boron Trioxide is used in the manufacture of glass for heat resistance.
Different types of Glasses and Uses
1. Soda lime glass (soft glass/silica glass)
The components used in the manufacture of soda lime glass are silica/silicon dioxide (SiO2), sodium carbonate (Na2CO3) and calcium carbonate (CaCO3). They are used as window doors, mirror, bulbs, bottles and jar. Soda lime glass is also called as Soda Glass.
2. Hard glass (heat resistant glass)
The components used in the manufacture of hard glass are silica (SiO2), potassium carbonate (K2CO3) and calcium carbonate (CaCO3). They are used as laboratory apparatus, factory and kitchen wares. Hard glass is also called as Potash glass.
3. Boro silicate glass
The components used in the manufacture of Boro silicate glass are boric oxide (B2O3), aluminium oxide (Al2O3), silica (SiO2) and sodium oxide. They are used as laboratory apparatus, factory and kitchen wares. Thermometer is also made from Boro silicate glass. It is also called as Pyrex Glass.
4. Flint glass (optical glass/lead glass)
The components used in the manufacture of Flint glass are silica (SiO2), potassium carbonate (K2CO3) and lead oxide (PbO). They are used as lenses and prisms.
5. Fibre glass
It is also called fibrous glass, is glass in the form of fine fibres. The fibres may be many times finer than human hair and may look and feel like silk. The flexible glass fibres are stronger than steel and will not burn, stretch, rot or fade. Manufacturer use fibre glass to make a variety of products. Fibre glass is woven into cloth to make such products as curtains and table cloths. The cloth does not change its properties when dyed. It will not wrinkle or soil easily and needs no ironing. Fibre glass textiles are also used for electrical insulation. In bulk form, fibre glass is used for air filters and for heat and sound insulation. Air trapped between the fibres makes it a good insulator. The components used in the manufacture of Fibre glass are silica (SiO2), sodium carbonate (Na2CO3) and calcium carbonate (CaCO3). They are used as industry insulator, vehicles, helmets and furniture.
6. Safety Glass
Safety glass (manufactured by pasting a weightless plastic sheet in between two glass plates) is used in manufacture of bullet proof screens, wind shields etc. In 1902, french chemist Edouard Benedictus dropped a glass flask on a floor; he found that it shattered, but kept its shape. Examining it, he noticed a film to which the glass had adhered. The film came from an evaporation of a collodion solution. Aware that automobile passengers in accidents were injured by flying glass, he developed a coating that made the glass safe. During the 1920's, laminated windshields gained wide acceptance in the American automobile industry.
Dyes
Dye is a chemical compound used to produce long lasting colours in materials. The textile industry uses dyes to colour fibres, yarns and fabrics. Dyes are also used to add artificial color to foods. Manufacturers also dye food, fur, ink, leather, paper, plastics and wood. Until the 1850's, all dyes were made from natural sources, such as various parts of plants or of certain animals. During the late 1800's and early 1900's, chemists developed synthetic dyes. These dyes hold their colour better and cost less to produce than natural dyes. Today, industry uses synthetic dyes almost entirely. In 1856, the English chemist William H.Perkin discovered a process for making dyes from coal tar previously an unwanted by-product of gas lighting. By the 1860's he was making eight different dye colours. Today more than 1000 different types of dyes are produced. Tetracaine is a dye that is harmful to humans.
Classification of Dyes based on origin
1. Natural Dyes
Natural dyes are derived from some plants, animals or minerals. The most common natural dyes are vegetable dyes from plant sources like roots, leaves, bark, wood and berries. fungi and lichens are other sources of natural dyes. Alizarin and Indigo are examples of natural dyes.
i. Alizarin
An orange-red crystalline solid, formerly extracted from madder root and used in dying. It is almost insoluble in water but dissolves in alcohol. Alizarin is now made from anthracene and yields a wide variety of dyes.
ii. Indigo
Indigo is a deep blue dye used to colour cotton and wool. It is also called indigotin. In past times, this dye was taken from the indigo plant, a member of the pea family that grows chiefly in india. Synthetic indigo is made from aniline, a coal-tar product.
2. Synthetic Dyes
The most common dyes available today are synthetic dyes. They are used in various products like paper, food, fabric, wood etc. It is because, they are cheap, bright, more colour fast and easy to use. Acid Dyes, Azo Dyes, Mordant Dyes and Basic Dyes are examples of Synthetic Dyes.
i. Acid Dyes
Acid dyes are anionic, water soluble dyes. Salts of chromium, iron, aluminium, tin or other metals are used with acid dyes. azo, anthraquinone or triphenyl methane-based are examples of Acid Dyes. Common mordants including salts of chromium, iron, aluminium, tin or other metals can be used with acid dyes.
ii. Azo Dyes
Azo dyes consists of 60 to 70 percent of all dyes used in food and textile industries. They are widely used to in leather, textile and some foods.
iii. Mordant Dyes
Mordant is a chemical that combines with dyes to prevent them from dissolving easily. The dye alone might wash out, but the compound formed by the dye and the mordant will not, so the colour is long lasting.
iv. Basic Dyes
Basic dyes are cationic, water-soluble dyes. It is mainly used in acrylic fibers and find some use for wool and silk. Acid mordants like Tannic acid, lactic acid and oliec acid combines with basic dyes.
