Category: Chemistry Notes PPT

Sulfur dioxide is an inorganic, heavy, colourless, and poisonous gas. It is produced in huge quantities in the intermediate steps of sulfuric acid manufacturing. Sulfur dioxide contains an irritating, pungent odour, familiar as the just-struck match smell. Occurring in nature in solution in the waters of some warm springs and volcanic gases, sulfur dioxide can usually be industrially prepared by the burning in the oxygen of sulfur or air or such compounds of sulfur as copper pyrite or iron pyrite. It has the chemical formula as SO2.

Structure and Bonding

SO2 is a bent molecule with the C2v symmetry point group. A valence bond theory approach by considering simply s and p orbitals would define the bonding in terms of resonance between the two resonance structures.

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The sulfur–oxygen bond holds a bond order of 1.5. There is support for this simple approach that does not invoke the participation of d-orbital. In terms of electron-counting formalism, sulfur atoms contain a formal charge of +1 and an oxidation state of +4.

Occurrence

This is found on Earth and exists in the atmosphere and very smaller concentrations at about 1 ppm.

On the other planets, this compound can be found in different concentrations, the most significant being the Venus atmosphere, which is the third-most significant atmospheric gas at 150 ppm. There, it condenses in the formation of clouds, and is a key component of chemical reactions in the atmosphere of the planet, and contributes to global warming. It also has been implicated as a key agent in the early Mars warming, with concentration estimates in the lower atmosphere as high as 100 ppm, though it exists only in trace amounts. As on Earth, on both Mars and Venus, its major source is thought to be volcanic. The Io-atmosphere, a natural satellite of Jupiter, is 90% sulfur dioxide, and the trace amounts are also thought to exist in the Jupiter atmosphere.

It is thought to exist as a block of ice in abundance on the Galilean moons—as subliming frost or ice on the Io’s trailing hemisphere, and in the crust and mantle of Europa, Callisto, and Ganymede, also possibly in liquid form and reacting readily with water.

Production

Primarily, sulfur dioxide is produced for the manufacturing of sulfuric acid. In the United States, in the year 1979, 23.6 million tonnes of sulfur dioxide were used in the same way, compared to 150 thousand tonnes, which is used for other purposes. Most of the sulfur dioxide is produced by elemental sulfur combustion. Some quantity of sulfur dioxide can also be produced by roasting pyrite and other sulfide ores in the air.

Reactions

Sulfur dioxide is a reducing agent, featuring sulfur in the oxidation state of +4. It is oxidized by halogens to form sulfuryl halides, like sulfuryl chloride. The chemical reaction is given as follows.

SO2 + Cl2 → SO2Cl2

Laboratory Reactions

Sulfur dioxide is considered one of the few common acidic yet reducing gases. Being acidic, this compound turns moist litmus pink, then white (because of its bleaching effect). It can be identified by bubbling it through the dichromate solution and turning the solution to the green from orange (Cr3+ (aq)). It also reduces ferric ions to ferrous.

Sulfur dioxide reacts with certain 1,3-dienes in a cheletropic reaction to produce cyclic sulfones. On an industrial scale, this reaction is exploited for sulfolane synthesis, which is an essential solvent in the petrochemical industry.

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Uses

The overarching and dominant use of sulfur dioxide is in the formation of sulfuric acid.

Precursor to Sulfuric Acid

Sulfur dioxide acts as an intermediate in the formation of sulfuric acid, being converted to sulfur trioxide, and then to the oleum, which can be made into the sulfuric acid. For this purpose, sulfur dioxide is made when the sulfur combines with oxygen. The conversion of sulfur dioxide to the sulfuric acid method is known as the contact process. Many billion kilograms are produced for this purpose annually.

As a Reducing Agent

Sulfur dioxide can also be a good reductant. It is also able to decolourize substances in the presence of water. Particularly, it is useful to reduce bleach for delicate materials such as clothes and papers. Normally, this bleaching effect does not last much longer. Oxygen reoxidizes the reduced dyes in the atmosphere by restoring the colour. Sulfur dioxide is used in the municipal wastewater treatment to treat chlorinated wastewater before release. It also reduces combined and free chlorine to chloride.

Aspirational Applications

Climate Engineering

Sulfur dioxide injections in the stratosphere have been proposed in climate engineering. The sulfur dioxide cooling effects would be the same as what has been observed after the large explosive eruption of Mount Pinatubo in 1991. However, this geo-engineering form would have uncertain regional consequences on the patterns of rainfall, for example, in the monsoon regions.

As a Refrigerant

Being condensed and possessing a high heat of evaporation easily, sulfur dioxide can be a candidate material for refrigerants. Before the chlorofluorocarbons development, sulfur dioxide was used as a refrigerant in home refrigerators.

Fibres are substances used to manufacture materials and fabrics such as cables, wires, clothes, curtains, and bedsheets. They are usually long, thin, and flexible, making them appropriate for manufacturing bendable, strong materials. Some of the most common types of fibres are cotton, silk, jute, linen, nylon, rayon etc. 

During manufacturing, several filaments of fibres come together to build a single product. For example, a cotton towel will require thousands of strands of processed cotton (a type of natural fibre) for its manufacturing. This is typically done in weaving factories.

Although fibres are mainly used in textiles, it should be noted that they have applications in almost all fields. Manufacturing of furniture, automobile, packaging, military devices, aerospace equipment, and other products that are used in day to day lives are some of the most common applications. Fibres are everywhere, making them an important part of modern life.

 

Types of Fibres

Depending upon the origin of the fibre, it is classified mainly into two types:

•  Natural fibres

•  Synthetic fibres

Natural fibre is anything that is procured from a natural source. An example of this type of fibre is cotton which is sourced from cotton seeds that grow on plants. Made of cellulose, an insoluble substance, cotton is fluffy and one of the most common fabrics used today to manufacture clothing materials. Both these types have subcategories. While natural fibres are sourced from vegetables, animals, and plants, synthetic (or manmade) fibres are produced using composition of chemical substances. 

 

Natural Fibres

 

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Natural fibres may be sourced from plants and animals. They are usually processed and turned into yarn, which can then be converted into a product. Natural fibres like cotton are preferred for clothing materials due to their physical properties. They are usually soft and lightweight, making them a sought-after type in textiles.         

Other than textiles, natural fibres are also widely used in non-textile applications. However, it should be noted that natural fibres are thinner and have less strength when compared with synthetic fibres.

Examples of Natural Fibres

Some of the most common types of natural fibres are listed below:

Cotton – a ubiquitous material, it is obtained from cotton seeds and is widely used for textiles. Cotton is soft and lightweight, thus making it a comfortable fibre for clothing materials. All of this has increased its demand in the marketplace

 Silk – obtained from an insect, it is produced from the substance used to form a cocoon

Jute – a stronger fibre among cotton, silk and jute, it is obtained from plants and used to create sacks and other packaging materials.

Wool – obtained from sheep and other furry animals, it is preferred for cloth manufacturing due to its capacity to hold heat. Preferred by people living in regions with cold climate, wool is also a very common clothing fibre

Advantages of Natural Fibres

1. Comfortable to Wear- Clothes made of natural fibre are way more comfortable to wear than clothes made of synthetic fibres, especially in the summer season. In the summer season when the human body releases more sweat, a person needs a breathable fabric to wear which can absorb the excess moisture. Natural fibres like silk and cotton have the properties of allowing enough ventilation in extremely humid and hot weather. These fibres do not stick to the skin and cause allergic reactions like rashes.

2. Exceptional Insulators- Natural fibres have the capacity to trap air in between them, not allowing it to escape into the atmosphere. This air that is captivated in the fabric micro-holes provides warmth and helps maintain a person’s body temperature even in cold, chilling weather conditions. This is the reason why many skiers, trekkers and other people living in cold areas prefer to wear wool or silk.

3.  More Sustainable- As the name suggests, natural fibres are obtained from nature. With the increasing global warming caused due to global warming, the human population needs to use more sustainable clothes, which are also proven to be harmless for the environment. Since these fibres are obtained from plants and animals, they are biodegradable and can be disposed of. Natural fibres can be replaced, recycled or reused time and again in a sustainable way.

 

Disadvantages of Natural Fibres 

1.  More Expensive- Due to having the properties of a great insulator, being more sustainable and more comfortable to wear, natural fibres are generally more expensive than synthetic fibres. Since they are extracted directly from nature, the cost of manufacturing them is often higher than the cost of manufacturing synthetic fibres. The manufacturing process of natural fibres involves taking good and healthy care of the plants and animals that provide these fibres. For example, a pashmina shawl is made of pashmina wool which comes from an indigenous goat living in the high-altitude ranges of the Himalayan mountains. 

2.  Easily Damageable- Natural fibres tend to not last as long as synthetic fibres. They damage easily due to various reasons. For instance, washing cotton or wool excessively can cause wrinkles and shrink of the fabric over time. Alternatively, natural fibres can also become good food for moths and other types of insects if kept exposed to the environment for a long period of time. Since these fibres are made of biodegradable material, various types of insects can feed on them and destroy the clothes completely.

3. Inconsistent Production- The production of natural fibres is sometimes not under the complete control of humans. Nature is independent and does not function according to human’s needs and desires. Its availability is heavily affected by natural disasters and calamities which cause high fluctuations in its production and price.  

 

Synthetic Fibres

 

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Also known as man made or artificial fibres, these are produced through chemical synthesis. Synthetic fibres were first developed in the nineteenth century. One of the main reasons for their creation was the need for stronger fibres that could withstand a lot of pressure. A lot of these fibres have extended use other than textiles.

Examples of Synthetic Fibres: Some of the most common types of synthetic fibres are listed below:

Rayon – a type of semisynthetic material, it is made from combining wood pulp (cellulose), carbon disulphide, and sodium hydroxide. It is used as an imitation of natural fibres like cotton and silk. There are also various subtypes of rayon.

Nylon – one of the most common synthetic fibre, it is entirely made of chemical processes.

Polyester – another common man made fibre, it is made chemically through plant proteins and is widely used in the manufacturing of plastic bottles. Its high strength and longer shelf life are the top characteristics

Several more types of synthetic fibres
are used for non-textile purposes. These are dacron, lyocell, modal, PAN, asbestos, spandex, and polyurethane. Some of these are mixed with natural fibres to create advanced fabrics that have both their characteristics. An example of this method is a stretchable fabric that is used for shirting and other clothing materials. It not only improves the look and feel but also adds to the quality.

 

Advantages of Synthetic Fibres

As mentioned above, synthetic fibres are preferred over natural fibres because of their advantages such as high strength and low making cost. This aligns with the exact need of why manmade fibres were invented in the first place.

In the twenty-first century, synthetic fibres make up for a large part of textiles due to the various advantages attached to them. This includes low cost, higher manufacturing profits, and higher strength that would extend their applications.

Some of these Advantages are Described in Detail Below:

High Strength – Plastic is one of the most popular types of synthetic fibres. It is so because of its series of positive qualities, one of which is strength. Plastic bottles, for instance, are stronger than those made from paper or wood. This same property is what gives synthetic fibres an upper edge over natural fibres

Low Cost and Easy Manufacturing – Manmade fibres can be mass-produced at a relatively lower cost than it takes to produce natural fibres. Moreover, natural fibres require a longer process while man made ones can be produced in a factory in lesser time. For example, cotton not only requires processing in the industry but also the time it needs for the plant to germinate, grow, and bear the seed that contains the cotton

Customization – One of the advantages of synthetic fibres is that they can be engineered to suit the needs. If a particular product requires the fibre to be less susceptible to breaking, it can be engineered through chemical or physical manipulation of the polymer

Most of today’s products, including clothing materials, use amalgamated fibres. As noted above, this allows the fabric or the combined substance to have the properties of both the fibres.

Disadvantages of Synthetic Fibres 

1.  Uncomfortable to Wear- Synthetic fibres can be very uncomfortable to wear as compared to natural fibres. These fibres absorb very little sweat from the body and that is why they are not recommended to be worn in humid weather conditions. Due to their lack of sweat absorbing capacity, they can cause itching and irritation to the sensitive human skin. Since they are made artificially by using chemicals and other synthetic materials, synthetic fibres have proven to cause different allergic reactions. Polyester, for example, can cause skin allergies and should be worn after careful inspection.

2.  Harmful for the Environment- These fibres are manufactured from chemicals and the by-products of petroleum, both of which are non-biodegradable in nature. Due to this, they take decades to decompose in the environment causing serious amounts of land and water pollution. Synthetic fibres also release poisonous gas upon burning that is harmful to humans to inhale and causes excess air pollution.

3. Non-resistant to Fire- The material used to make synthetic fibre- polymer- is easily flammable. It melts and shrinks very easily when it gets in contact with high heat or fire and can stick to the skin of the person wearing this synthetic cloth. Therefore, it is advised to avoid wearing any synthetic clothes, especially acrylic fabric, during cooking or doing any activity that involves the use of fire.

Carboxylic acids are compounds containing the carboxyl functional group in their molecules. The carboxyl group is made up of carbonyl and hydroxyl groups and therefore, the name carboxyl is derived from carbo (from carbonyl) and oxyl from the hydroxyl group. The carboxylic acids may be aliphatic or aromatic depending upon whether the -COOH group is attached to the aliphatic alkyl chain or aryl group respectively.

The functional groups that consist of a Carbonyl Group (C=O) along with a hydroxyl group (O-H) which is attached to the same carbon atom are known as carboxyl groups. The formula for Carboxyl Groups is-

-C(=O)OH

Acids with the presence of one carboxyl group are termed carboxylic acids and since they are proton-donors, they are also known as Bronsted-Lowry acids. Acids with the presence of two carboxyl groups are known as dicarboxylic acids and the ones with the presence of three carboxyl groups are known as tricarboxylic acids.

Salts and esters of carboxylic acids are known as carboxylates.

Though the IUPAC nomenclature of carboxylic acids is ‘oic acids’ in the suffix, ‘ic acids’ is used more commonly.

Qualitative Test for Carboxylic Acid

The following tests are performed for the identification of carboxylic acid.

1. Action with Blue Litmus

All carboxylic acids turn blue litmus red.

Procedure-

• Place the droplet of the liquid, solid or crystal on a moist blue litmus paper and observe the colour change.

• If the red colour changes to blue, it indicates the presence of a carboxylic group.

2. Action with Carbonates and Bicarbonates

Carboxylic acids decompose carbonates and bicarbonates evolving carbon dioxide with brisk effervescence. 

Carboxyl groups react with sodium hydrogen carbonate releasing carbon dioxide gas which can be identified by the effervescence produced. To distinguish carboxylic acids from phenols, this test can be used.

[RCOOH + NAHCO_3 rightarrow RCOONa + Co_2 uparrow + H_20]

Procedure-

• Take one ml of organic liquid in a test tube and add a pinch of sodium bicarbonate [(NaHCO_{3} )] to it.

• If carboxylic acid is present in the organic compound, a brisk effervescence is observed.

3. Carboxylic Acid NaHCO3 Mechanism

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The reaction of carboxylic acids with aqueous sodium carbonate solution leads to the evolution of carbon dioxide producing brisk effervescence. However, most phenols do not produce effervescence with an aqueous solution of sodium bicarbonate. Therefore, this reaction may be used to distinguish between carboxylic acids with sodium bicarbonate or sodium carbonate, the carbon dioxide evolved comes from Na₂CO₃ or NaHCO₃ and does not form a carboxyl group.

4. Formation of Ester

When carboxylic acids are heated with alcohols in the presence of concentrated sulphuric acid and hydrochloric acid, esters are formed. The reaction is reversible and is called esterification.

Carboxylic acids react with alcohol when there is a presence of sulphuric acid to form an ester that has a fruity smell.

Procedure-

• To 0.1 g of the organic compound add 1 ml ethyl alcohol and one or two drops of concentrated sulphuric acid in a test tube. After heating the mixture in a water bath for about five minutes, pour it into a beaker that has water. If a fruity smell is observed, it indicates the presence of the carboxyl group in the organic compound. 

[RCOOH + C_2H_5OH rightarrow COOC_2H_5 + H_2O]

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5. Fluorescein Test

This test is used for the identification of the dicarboxylic group. When the dicarboxylic compound is heated, it produces acid anhydride. This anhydride reacts with resorcinol in the presence of Conc. H₂SO₄ and produces a fluorescent dye. 

Procedure-

• Take a small amount of organic compound and heat it with resorcinol and one or two drops of concentrated sulphuric acid in a clean and dry test tube. 

• After a few minutes, the solution turns dark-brown and a liquid is formed.

• Add a few drops of this solution to a dilute NaOH solution.

• If the solution turns red with green fluorescence, it indicates the presence of dicarboxylic acid.

6. Reaction with FeCl₃

Some carboxylic acids give precipitates when they react with iron trichloride. For example, acetic acid gives puff coloured precipitate.

Did You know?

• Methanoic acid is used in leather tanning

• Methanoic acid is used as an antiseptic.

• Benzoic acid and some of its salts are used as urinary antiseptics.

• Carboxylic acid esters are used in perfumery.

When we hear the word Thermodynamics from our teacher, we think of some behemoth concept that is going to take hours of study to understand it completely. Well, thermodynamics is a bit complicated; there is no doubt about it. But once you go through this article, you will understand the importance of thermodynamics and why you need to learn it as a science student. Once you understand the concepts of the thermodynamics, you will see how these laws are working in our daily lives and helping mankind to discover new things. Today we are going to talk about the laws of thermodynamics. The thermodynamics definition, along with chemical thermodynamics. So, clear up your mind and give us your full concentration because you need it to understand its concepts. 

Before we talk about the laws of thermodynamics, we first need to clear out the thermodynamics definition. The relationship of heat with the other forms of energy is the branch of science which is called thermodynamics. To be more precise, it is a study of thermal energy and how it is converted and how does it affect the matter when the conversion of the energy is taking place. 

Now talking about thermal energy, it is the energy present in the given substance due to its temperature—one of the thermodynamics examples which will show you what thermodynamics is in real life. The movement of the steam engine when the temperature gets high water becomes steam and makes the pistons to move. 

There are four main laws of thermodynamics, but in most cases, we only need the first three. In addition to this, the potential of molecular networks and every other minute detail of its design can be studied using thermodynamics. Likewise, It was first introduced as a theory that was entirely based on macroscopic phenomena such as temperature, pressure, volume along with energy. 

When two objects are in contact with each other. There is no transfer of heat and energy between them, and then you can say these two objects are in thermal equilibrium, this is the zeroth law of thermodynamics.

Laws Of Thermodynamics

Now, let’s move to the three important laws of thermodynamics chemistry. 

The First Law of Thermodynamics 

This law in a lot of textbooks is also said to be the law of conversation of energy. This means energy can’t be created, nor can it be destroyed by any means. As a result, energy gets converted to other forms.

In simple words, the first law states that whenever heat is being added in a system from the external source. Some of the energy stays with the system, and the rest of it gets consumed from work. The energy left in the system increases the internal energy. Internal energy is the total of your kinetic energy and potential energy. 

Isothermal process, Isobaric process, and Isochoric process are some of the applications of the first law of thermodynamics.

The Second Law of Thermodynamics 

“The total change in the entropy of any given system plus its surroundings will always make an increase in the spontaneous process,” this is called the second law of the thermodynamics. Entropy in laymen’s terms is said to be a measure of the randomness of a given system. Every system that you have around you wants to reach its maxim randomness and disorder. 

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(ice melts due to heat and forms water, providing second law of thermodynamics)

One great example of this law can be seen in your kid’s room. Every time your mom cleans up your younger sibling’s room after a few minutes, it will again become messy as toys will be thrown on the floor, and painting colours will come out from the drawer. Another example is the different states of liquid when in the solid form, ice, the molecules are tightly packed. On the other hand, when the ice melts and forms liquid, the molecules become disordered and random. 

Third Law of Thermodynamics 

“As the temperature around perfect crystal goes to absolute zero, its entropy also reaches to zero” this means thermal motion ceases and forms a perfect crystal at 0K. While there is any thermal motion found within the crystal at 0K, the atoms in the crystal will start vibrating, and it will lead to disorder, thus, violating the third law of thermodynamics. 

Application Of Thermodynamics

Every vehicle you drive or see on the road, sky, and even in the sea, all their engines are working based on the second law of thermodynamics. It doesn’t matter if they are using petrol or diesel engine the laws will work in the same way.  

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(refrigerators usings laws of thermodynamics to keep food fresh during summertime)

Secondly, the refrigerators we have in our homes, deep freezers, and other air conditioning systems also work on the second law of thermodynamics. 

Lastly, all the compressors and the blower fans you see around you are using various thermodynamic laws and cycles to keep it working continuously.

Titanium dioxide is an oxide of titanium metal and is an inorganic compound. The titanium dioxide formula is TiO2. It is made up of two atoms of oxygen and one atom of titanium which is the 9th most common element in the crust of the earth and it is present generally in plants and animals. In order to form titanium dioxide, the metal of titanium reacts naturally with oxygen. This oxide is commonly found in sands, soils, ores, indigenous, and dust.

It is also referred to as titanium(IV) oxide. The titanium dioxide colour is white, insoluble in water but sometimes the mineral forms of this solid can appear black. It is used for a variety of purposes such as in paints, food colouring, and sunscreen. Titanium dioxide properties make it usable for different industries such as food industries, cosmetic industries, etc. 

Structure of Titanium Dioxide

Titanium exhibits octahedral geometry in all three of its main dioxides. The geometry of the rutile type of titanium dioxide is distorted hexagonal on the other side two different types of TiO2 i.e. anatase and brookite are cubic. The structure of rutile is a general pattern that is being adopted by other difluorides and dioxides of metals e.g. RuO2 and ZnF2.

The structure of molten titanium dioxide is local where each titanium (Ti) is coordinated to around five atoms of oxygen on average. 

           

 

The Production Process of Titanium Dioxide

Some of the production processes of titanium dioxide are given below

In the chloride process, the ore from which titanium dioxide is prepared is treated with Cl and C to obtain titanium tetrachloride which is a volatile liquid that is later purified through the distillation method. To produce titanium oxide and regenerate chlorine in this process, the TiCl4 is treated with oxygen.

Ilmenite is treated with sulphuric acid in the sulphate process to extract iron(II) sulphate pentahydrate. This process is used for the preparation of titanium dioxide.

By many specialized chemistries, films of TiO2 are prepared. These are used for different speciality purposes. Sol-gel routes engage in the hydrolysis of titanium alkoxides, such as titanium ethoxide. The reaction is given below.

Ti(OEt)4 + 2H2O → TiO2 + 4EtOH

For the preparation of films, this technology is suitable. The alkoxide is volatilized in this application and then decomposed on contact with a hot surface. The reaction is as follows.

Ti(OEt)4 → TiO2 + 2Et2O

Titanium Dioxide Uses

Some of the titanium dioxides use of pigment-grade titanium dioxide and ultrafine-grade, or nanoscale titanium dioxide are mentioned below.

1. Pigment-grade Titanium Dioxide

Pigment-grade type of titanium dioxide or titanium dioxide pigment is used in a wide range of uses that need high opacity and brightness. In fact, most surfaces and items that are coloured in white, pastel, and dark shades contain this oxide. The applications of pigment-grade titanium dioxide are given below in detail.

• Paints and Coatings: It is used for the purpose of coating in the paint industry because its properties of opacity and durability of titanium dioxide help to ensure the longevity of the paint and protection of the surfaces which are painted.  

• Plastics, Adhesives, and Rubber: Titanium dioxide is helpful to reduce cracking, fading and the brittleness occurring in plastics and other materials as a result of exposure to light.

• Cosmetics: In some cosmetic products pigment-grade titanium dioxide is used to help in order to hide blemishes and brighten the skin. For having the same effect it is used in the thinner coatings of make-up material.

• Paper: Titanium dioxide (TiO2) is used in the paper industry for coating paper, brighter, making it whiter and more opaque.

• Food Materials and Medicinal uses: The opacity to visible and ultraviolet light offered by titanium dioxide protects products of food items, beverages, supplements and pharmaceuticals from degradation in premature periods and enhances the longevity of the product. Titanium dioxide in medicine is continuously used by pharmaceuticals in the form of titanium dioxide tablets. This type of titanium oxide is used in titanium dioxide IP tablets, uses capsule coatings and as a decorative aid in some foods.

2. Ultrafine-grade or Nanoscale Titanium Dioxide

The following are the applications of ultrafine-grades of titanium dioxide:  

• Sunscreen: When nanosized titanium dioxide or ultrafine titanium dioxide comes in contact with sunlight it becomes transparent to visible light and serves as an efficient Ultraviolet absorber of light. Nano-titanium dioxide does not reflect visible light as the size of the particle is very small but does absorb UV light and enables a transparent barrier that protects the skin from the harmful rays of the sun. Titanium dioxide side effects occur when used in an excessive amount on the skin so used while taking precautionary measurements.

• Catalysts: This type of titanium oxide also works as a supporting material for the applications of catalysts. Other major uses are the removal of harmful exhaust gas emissions in the automotive industry and the removal of nitrous oxides in power stations.

Titanium Facts

• The body of human beings rarely rejects titanium metal hence it is sometimes used in medical implants. 

• Titanium (Ti) is twice strong as aluminum (Al) metal. For the usage of high-stress, there used to be a requirement of a strong metal at those places titanium metal is very useful. 

Conclusion

Pure titanium dioxide is powdered in white, fine material that gives a bright appearance. It is popularly known by many people because it is an active ingredient in sunscreen. In sunscreen, it acts as a filtering material of harmful  UV rays. We get to know all the related information of titanium dioxides such as structure, production, and TiO2 applications. Because of its applications, it is produced widely by titanium dioxide manufacturers.

Transition Metals Definition – The d-block elements are called transition metal. The d-block consists of the elements that are lying in between the s and p blocks. The position of this block is between groups 2 and 13 in the periodic table. It starts from the fourth period onwards. In these elements, the outermost shell contains one or two electrons in their s-orbital but the last electron enters the last but one d subshell (n-1) d. The properties of the elements of this block generally lie between the elements of s  block and p block. 

Transition Elements List

The transition elements list contain the metals that have incompletely filled d-subshells in their ground state or any one of their oxidation states. Metals included in the transition elements list are:

First Transition Series

The first transition series consists of elements from scandium, Sc (Z = 21) to zinc, Zn (Z = 30) i.e scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc. The first transition element is scandium, in scandium, the 3d orbital starts filling up and its electronic configuration is [Ar] 4s² 3d¹. As we move from scandium onwards, 3d orbitals get filled up more and more till the last element, zinc, in which the 3d orbitals are completely filled [Ar] 4s² 3d¹⁰.

Exceptional Electronic Configuration of Chromium (Cr) and Copper (Cu) in Transition Series

The configuration of chromium and copper are anomalous. We know that half-filled and filled electronic configurations have extra stability associated with them. Moreover, the energy difference between 3d and 4s orbitals is not large enough to prevent the electron from entering the 3d orbitals. Thus, to acquire increased stability, one of the 4s electrons goes to nearby 3d orbitals so that the 3d orbital becomes half-filled in the case of chromium and filled in the case of copper respectively. Therefore, the electronic configuration of chromium is [Ar] 3d⁵ 4s¹ rather than [Ar] 3d⁴ 4s² while that of copper is [Ar] 3d¹⁰ 4s¹ instead of [Ar] 3d⁹ 4s². 

Second Transition Series

The 2nd transition series consists of elements from yttrium, Y (Z = 39) to cadmium, Cd (Z = 48), i.e., yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver and cadmium. This series involves the filling of 4d-orbitals. 

Third Transition Series

This series consists of elements of lanthanum and from hafnium to mercury i.e., lanthanum, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, and mercury. In between Lanthanum and Hafnium there are fourteen elements called lanthanides which involve the filling of 4f-orbitals and do not belong to this series. The elements of the d-block third series involve the gradual filling of five d-orbitals. It may be noted that, in the second and third transition series, there are many anomalous configurations in comparison to those of the first transition series. These are accredited to the factors like nuclear electron and electron-electron forces.

Fourth Transition Series

It involves the filling of a 6d subshell starting from actinium (Z=89); which has the configuration 6d¹ 7s². This fourth transition series in periodic table is incomplete as given in the table below:

General Characteristics of Transition Metals Elements are:

have high tensile strength.

Ductility.

Malleability.

High thermal conductivity.

Electrical conductivity.

Metallic lustre.

• Except for mercury which is liquid at room temperature, other transition elements have typical metallic structures.

• Transition elements possess a high melting point and high boiling points.

• The value of heats of vaporisation is higher than the non-transition elements.

• The transition elements have very high densities as compared to the metal of group 1 and 2nd (s block).

• The first ionisation energies of d block elements are highe
  r than those of s block elements but are lesser than those of p block elements.

Did You Know?

• The fundamental difference in the electronic configuration of transition elements and representative elements is that in the representative elements the valence electrons are present only in the outermost shell. On the other hand, in the transition elements, the valence electrons are present in the outermost shell (ns) as well as the d orbital of the penultimate shell.

• The ionization energy of chromium and copper have an exceptionally higher energy than those of their neighbours.