Category: Chemistry Notes PPT

Tungsten carbide is a chemical compound comprising equal parts of tungsten and carbon atoms. In its most simple form, tungsten carbide is a fine grey powder, but it can be pressed and shaped into shapes through a method called sintering for use in industrial equipment, cutting tools, abrasives, armour-piercing shells and jewellery. We have covered all of the important aspects of tungsten carbide in this article, including its description, tungsten carbide rings, applications, price, and properties. Wedding rings are often made of tungsten carbide. Tungsten carbide rings are much more durable than gold and silver rings. Tungsten rings are rated between 8 and 9 on the Mohs scale of hardness. 

Structure of Tungsten Carbide

A hexagonal shape of WC exists, as well as a cubic high-temperature form, tungsten carbide, with a rock salt structure. The hexagonal structure is made up of a plain hexagonal lattice of metal atoms of layers lying directly over one another, therefore, not closely packed), with carbon atoms filling half the interstices, giving both tungsten and carbon a normal trigonal prismatic, 6 coordination. The bond lengths between tungsten atoms in a hexagonally packed layer are 291 pm, the shortest distance between tungsten atoms in neighbouring layers is 284 pm, and the tungsten carbon bond length is 220 pm, according to the unit cell dimensions. The length of the tungsten-carbon bond is thus equivalent to the single bond in W(CH3)6 (218 pm), in which tungsten is highly twisted trigonal prismatically coordinated.

Properties of Tungsten Carbide

Physical Properties of Tungsten Carbide

• Tungsten carbide has a high melting point of 2,870°C (5,200°F).

• It has a boiling point of 6,000°C (10,830°F).

• When heated to 1 atmosphere (100 kPa), the thermal conductivity of 110 Wm^-1K^-1.

• It has a coefficient of thermal expansion of 5.5 µm·m^-1·K^-1.

• Tungsten carbide is extremely stiff, with a Mohs hardness of 9 to 9.5 and a Vickers hardness of about 2600. 

• Young’s modulus is around 530–700 GPa, the bulk modulus is around 630–655 GPa, and the shear modulus is around 274 GPa. 

• It has a Poisson’s ratio of 0.31 and has an ultimate tensile strength of 344 MPa, an ultimate compressive strength of around 2.7 GPa.

• A longitudinal wave (sound) travelling through a thin rod of tungsten carbide travels at 6220 m/s. 

• The low electrical resistivity of tungsten carbide (about 0.2 m) is equivalent to that of other metals (e.g. vanadium 0.2 m).

• Both molten nickel and cobalt readily wet tungsten carbide. The phase diagram of the W-C-Co system reveals that WC and Co have a pseudo-binary eutectic.

• Controlling the carbon content in WC-Co cemented carbides is critical due to the potential for carbides to form and the brittleness of these phases.

• In the presence of a molten phase, such as cobalt, abnormal grain growth has been observed in the sintering of tungsten carbide, with significant implications for the product material’s efficiency.

Chemical Properties Tungsten Carbide

• There are two well-known tungsten and carbon compounds: WC and tungsten semicarbazide, W₂C. Coatings may contain both substances, with the proportions varying depending on the coating process.

• By heating the WC phase to high temperatures with plasma and then quenching in inert gas, another meta-stable tungsten and carbon compound can be produced (plasma spheroidization).

• The non-stoichiometric high-temperature phase WC1-x  exists in a meta-stable form at room temperature as a result of this process, which causes macrocrystalline WC particles to spheroidize. As compared to other tungsten carbide compounds, this phase’s fine microstructure offers high hardness (2800-3500 HV) and strong toughness. Because of this compound’s meta-stability, it has lower high-temperature stability.

• At high temperatures, WC decomposes into tungsten and carbon, which can happen during high-temperature thermal sprays, such as in HVOF and HEP methods.

• At 500–600 °C (932–1,112 °F), WC begins to oxidise. It is acid-tolerant and is only targeted at room temperature by hydrofluoric acid/nitric acid (HF/HNO₃) mixtures. It is unreactive to dry H₂ up to its melting point and reacts with fluorine gas at room temperature and chlorine above 400 °C or 752 °F. In aqueous hydrogen peroxide solutions, finely powdered WC readily oxidised. It reacts with aqueous sodium carbonate at high temperatures and pressures to form sodium tungstate, which is used to recover scrap cemented carbide due to its selectivity.

Synthesis of Tungsten Carbide

Tungsten carbide is made by reacting tungsten metal with carbon at temperatures between 1400 and 2000 degrees Celsius. A proprietary lower temperature fluid bed process that reacts to tungsten metal or blue WO₃ with CO/CO₂ mixture and H2 between 900 and 1200 °C is one of the other methods.

WC can also be made by heating WO₃ with graphite at 900 degrees Celsius directly or in hydrogen at 670 degrees Celsius followed by carburization in argon at 1000 degrees Celsius. The following chemical vapour deposition methods have been investigated:

At 670 °C (1,238 °F), tungsten hexachloride is reacted with hydrogen (as a reducing agent) and methane (as a carbon source).

WCl₆ + H₂ + CH₄ → WC + 6 HCl

At 350 °C (662 °F), tungsten hexafluoride is reacted with hydrogen (as a reducing agent) and methanol (as a c
arbon source).

WF₆ + 2 H₂ + CH₃OH → WC + 6 HF + H₂O

Uses of Tungsten Carbide

Cutting Tools for Machining

Cutting tools made of sintered tungsten carbide are extremely abrasion-resistant and can withstand higher temperatures than normal high-speed steel (HSS) tools. Carbide cutting surfaces are often used for machining carbon steel and stainless steel, as well as in applications where steel tools will wear out easily, such as high-volume and high-precision manufacturing. Carbide tools provide a better finish on parts than steel tools because they hold a sharp cutting edge longer, and their temperature tolerance allows for faster machining. Cemented carbide, solid carbide, hard metal, and tungsten-carbide cobalt are common names for the element. It’s a metal matrix composite in which the aggregate is tungsten carbide particles and the matrix is metallic cobalt. Rotary Carbide Burrs, also known as rotary files or die grinder pieces, are used to cut, shape, and grind as well as remove sharp edges.

Ammunition

Tungsten carbide is commonly used in armour-piercing ammunition, either as a monolithic sintered type or as a tungsten carbide cobalt composite, particularly where depleted uranium is not available or is politically unacceptable. Tungsten carbide was only used in the production of machine tools and a limited number of projectiles. Due to its combination of high hardness and density, it is an efficient penetrator.

The sabot form of tungsten carbide ammunition is now the most popular. One of the most common forms of saboted small arms ammunition is SLAP, or saboted light armour penetrator, in which a plastic sabot is discarded at the barrel muzzle. Non-discarding coats, regardless of material, are viewed as bullets rather than sabots. Both designs, on the other hand, are popular in light armour-piercing small arms ammunition.

Mining and Foundation Drilling

Top hammer rock drill bits, downhole hammers, roller-cutters, longwall plough chisels, longwall shearer picks, raiseboring reamers, and tunnel boring machines are all made of tungsten carbide. It’s most commonly used as a button insert, placed in a steel matrix that serves as the bit’s substance. The softer steel matrix holding the tungsten carbide button wears away as well, revealing more of the button insert.

Nuclear

Tungsten carbide is also a good neutron reflector, which is why it was used in early nuclear chain reactions research, particularly for weapons. On August 21, 1945, at Los Alamos National Laboratory, Harry Daghlian dropped a tungsten carbide brick onto a plutonium sphere known as the demon heart, causing the subcritical mass to go supercritical with the reflected neutrons, resulting in a criticality accident.

Sports Usage

Many hikers use trekking poles for balance and to relieve pressure on their leg joints. Carbide tips achieve traction when placed on hard surfaces and last much longer than other forms of tips.

Rollerski tips are commonly made of carbide, while ski pole tips aren’t so they don’t need to be as hard to crack through layers of ice. Many skiers use roller skiing to practise during the summer months because it resembles cross-country skiing.

Snowmobiles’ drive tracks can be inserted with sharpened carbide tipped spikes, also known as studs. On ice surfaces, these studs improve traction. Under each snowmobile ski, longer v-shaped segments fit into grooved rods called wear carbide rods. On harder ice surfaces, the relatively sharp carbide edges improve steering. If the snowmobile has to crossroads or other abrasive surfaces, the carbide tips and segments minimise wear.

Tungsten carbide studs in vehicle, motorcycle and bicycle tyres improve traction on ice. Steel studs are commonly favoured because of their superior wear resistance.

Traction Improving Device

Tungsten carbide is often used in farriery or horseshoeing, to increase traction on slick surfaces like roads or ice. To mount the shoes, carbide-tipped hoof nails can be used; in the United States, borium – tungsten carbide chips in a matrix of softer metals like bronze or mild steel – can be welded to small areas of the shoe’s underside before mounting. Different types of tungsten metal prices can be easily found on various e-sites.

Surgical Instruments

Surgical devices made of tungsten carbide are used in open surgery (scissors, forceps, hemostats, blade-handles, and so on) and laparoscopic surgery (graspers, scissors/cutter, needle holder, cautery, and so on). They are more expensive than stainless-steel equivalents and need more delicate handling, but they work better.

Jewellery

Tungsten Carbide Ring- Due to its extreme hardness and high scratch resistance, tungsten carbide, usually in the form of cemented carbide (carbide particles brazed together by metal), has become a common material in the bridal jewellery industry. Even though it has high impact resistance, its extreme hardness means it can be broken in some conditions. Some people think this is useful because a tungsten ring will crumble in an impact, allowing it to be easily removed, while precious metals would bend flat and need cutting. The hardness of tungsten carbide is about ten times that of 18k gold. Consumers are drawn to it because of its advanced nature, in addition to its design and high finish. If a ring must be removed quickly, special tools, such as locking pliers, may be needed (e.g. due to a medical emergency following a hand injury accompanied by swelling). Tungsten rings price is not overly costly, but the consistency varies.

Types of Tungsten Ring

• Tungsten rings for men

• Tungsten rings for women

• Black tungsten rings

• Diamond tungsten ring

• Wood tungsten ring

• Exotic tungsten ring

Did you know that?

• The spinning ball in the tips of ballpoint pens that disperses ink during writing is made of tungsten carbide.

• Tungsten carbide is a common material used in the manufacture of gauge blocks, which are used in dimensional metrology to produce precise lengths.

The Ullmann reaction, also called Ullmann coupling, is an organic reaction that is used to couple two molecules of aryl halide for forming a biaryl with the help of copper metal and thermal conditions. The mechanism for the Ullmann reaction is not entirely understood, however, there are two popular mechanisms. The radical mechanism includes the single electron transfer from the copper metal to the alkyl halide for forming an aryl radical. Two aryl radicals then react and form the final biaryl product. The second mechanism includes an oxidative addition of the copper to the aryl halide and is followed by a single electron transfer and forms an organocuprate reagent. The organocuprate then performs another oxidative addition on an aryl halide and reductive elimination takes place that results in the final biaryl product. In this article, we will learn about the Ullmann reaction, Ullmann reaction mechanism, and the Ullmann reaction application.

Ullmann Coupling Reaction Mechanism

As mentioned, there are two different Ullmann coupling mechanisms. Both are shown as follows:

1. Radical mechanism

2. Mechanism involving the aryl copper intermediate

Mechanism of Ullmann Reaction in Detail

Let us now take a look at the mechanism in detail.

1. Step 1:

The mechanism of the Ullmann reaction includes the formation of an active copper(I) species when the aryl halide is introduced to an excess of metallic copper under very high temperatures, above 200C.

2. Step 2:

The resulting copper(I) species further undergoes oxidative addition with another haloarene molecule and links the two molecules.

3. Step 3:

In the final step of the Ullmann coupling mechanism, the copper compound which is formed by the two aryl halide molecules undergoes a reductive elimination and results in the formation of a new carbon-carbon bond between both the aryl compounds.

Role of Copper in Ullmann Reaction

The Ullmann reaction is a metal-catalyzed coupling of halogene-benzene derivatives which leads to biaryls (an aryl group is a group obtained by removing a hydrogen atom from and aromatic compound; if the aromatic compound is benzene, the aryl is the phenyl group) and the larger carbon-based structures. This reaction offers an unprecedented opportunity for accessing the molecular functionality by improving the mechanical stability and electron conductance, that is essential for the advancement in the realization of organic-based electronics.

Catalysts, like copper, provide an alternative pathway through which the reaction can proceed, in which the activation energy is slightly lower. It thus increases the rate at which the reaction comes to the equilibrium. The catalyst itself takes part in the reaction without undergoing any permanent chemical change, although it can undergo a physical one. In the classical Ullmann reaction, the oxidation of copper along with the formation of molecular cuprate intermediates and copper halides as side reaction products precedes the cross-coupling reaction. However, there is general agreement that at a certain point of the reaction a copper-coordinated structure is formed, the debromination mechanism, that is the rate-limiting step of the reaction, has been scarcely investigated. At this point, it is not clear whether the formation of radicals or organo-copper complexes or the oxidative addition process precedes the formation of the biaryl compound.

Ullmann Reaction Application

Now that you know about the Ullmann coupling reaction, its nomenclature, the mechanism of the reaction and the importance of copper in the reaction, let us have a look at the applications of the Ullmann reaction.

The Ullmann reaction applications are as follows:

1. Biphenylenes are obtained from 2, 2- diiodo biphenyl through the Ullmann reaction.

2. Ullmann reaction can also be used for the closure of the five-membered rings.

3. An unsymmetrical reaction can be achieved when one of the reactants is provided in excess.

4. Chiral reactants are coupled into a chiral product through the Ullmann coupling reaction.

Significance of Ullmann Reaction

The Ulmann reaction has its own significance when it comes to the organic chemistry. Let us now look at what it is. 

The Ullmann coupling reaction has become a powerful and essential tool in the organic synthesis and drug discovery. Copper-catalyzed Ullmann reactions were very well developed recently by employing the novel ligands and ancillary synthetic tools. Amongst the many exciting and rapid developments of the Ullmann coupling reactions, its is believed that the green synthetic methodologies, such as metal-, ligand-, and additive-free conditions, recyclable heterogeneous catalysts, and microwave-assisted synthesis will continue to have a significant impact on this field. 

The atmosphere is the protective air envelope around the earth. Air contains oxygen that we breathe and protects us from the harmful UV rays of the sun.  Air is a mixture of different gases and is all around us. We cannot see it but it is essential for all living organisms. Atmosphere consists mainly of nitrogen (78%), oxygen (21%), argon (0.93%), carbon dioxide (0.03%) and other gases like helium, ozone, argon and hydrogen (0.04%). Air in the atmosphere has several critical functions that help in the sustenance of life. 

Pure air doesn’t have any scent or colour. But classically air contains dust, pollen, spores, and other contaminated particles which are known as ‘air pollution. As far as the atmosphere is concerned, air has several critical functions that will help to sustain life.

What are the Important Uses of Air?

The importance of air lies hereunder:

The water cycle ensures that life around the planet receives the water it needs by replenishing lakes, rivers and other waterways and helping in irrigating parched lands.

Air is important for recycling of carbon that comes into the biosphere from fossil fuel combustion, the decay of dead animals, and the eruption of volcanoes. Most living organisms exhale carbon dioxide into the air during respiration. Plants utilize the exhaled carbon dioxide present in the air for photosynthesis, which produces oxygen.

Air contains carbon dioxide and other greenhouse gases that absorb infrared radiation released from the earth. This phenomenon, called The greenhouse effect keeps  the earth’s surface warm which would not have been possible otherwise.

Air helps protect us from harmful radiations and celestial particles like the x-rays, cosmic rays, meteors, asteroids can be too destructive. Air also reduces the possibility of destruction by meteorites and asteroids.

People can hear sound only because air carries sound waves from one point to another. 

Due to air molecules causing violet and blue wavelengths of sunlight to scatter, the sky appears blue. 

Climatic phenomena like rain, snow, and sea storms are all attributes of air.

Essential Uses of Air

Below are the essential uses of air with brief explanation:

Sustain Life and Growth

Air has oxygen as one of its key elements. It is vital for the sustenance of life on earth as all living organisms and plants depend on oxygen in the air for breathing in oxygen. There are many uses of air in daily life. In living organisms, oxygen is supplied to all the cells in the body through blood. Similarly, plant cells also utilize carbon dioxide in the air to produce food that we eat to get energy. 

Pollination

Pollination is the process where pollen grains from the male flower reach the female flower. Air is also an important medium for transportation of these pollen grains without which flowers could not bloom and fruits could not be produced.

Land and Sea Breezes

During conditions of extreme heat, the land surface becomes hotter compared to oceans or sea surfaces. The hot air on the land rises rapidly and the place is filled by the cool air coming from the ocean. This cycle of rapid movement of air is useful in maintaining temperature over land.

Monsoon

Monsoon is of critical importance as it provides for irrigation and thus, production of crops.  This monsoon is aided by the winds which carry the clouds from above the oceans of the world. Thus, air plays an important role in the movement of clouds and its absence can cause drought-like conditions in some regions. 

Aerodynamics

Parachutes and hot air balloons use air for mobility. Therefore, to land safely, it uses the function of buoyancy where hot air balloons travel up in the air using hot air as a medium. Air also enables airplanes to fly and travel from one place to another.

Land Transportation

Air-filled tires, commonly used for land-based transport, reduce the friction between the tire and the solid surface, thus enabling automobiles to move faster. 

Transportation in Airplanes

Air makes transportation easier as it facilitates the smooth movement of airplanes. It is a common mode of transport globally across long distances. One can avoid obstacles through air travel. Several other living beings like birds and insects depend on air for mobility. Air also has several tiny living organisms called bioaerosols. They cannot fly on their own and depend on air for transportation. 

Minimizing Pollution

Major cities are getting choked with pollutants, dust, smog, and chemicals preventing visibility and causing several health hazards. Air is useful in minimizing air pollution by spreading it across vast areas instead of clogging it at a specific place.

Wind Power Energy

Air is a good source of wind energy. In recent times there is a significant increase in the usage of wind energy to generate electricity by using wind turbines. Turbines rotate with the wind flow and thus generate electricity. 

Combustion

Combustion is a chemical reaction between oxygen in the air and fuel accompanied by the production of heat energy. In simple terms, it is called burning which is a chemical reaction. It is similar to photosynthesis  but in reverse.

Some Examples of Combustion are as Follows:

• Generating heat by burning coal or wood·        

• Utilizing petrol or diesel as sources for transportation (car)·        

• Utilizing natural gas as fuel for cooking·        

• Utilizing fuel as an energy source in thermal power plants      

• Fireworks during festivals or events

Conclusion

Air is a natural resource and is available plentifully. It is an essential element of nature that supports life on earth. Air is equally important for living organisms for their survival just like water. Air is very useful and has much significance.  

The significance of air is as follows:

Oxygen present in the air is one of the main elements for living life. All living things such as animals, birds, and human beings need oxygen for survival. Whereas, Nitrogen & Carbon dioxide is required for plants and their growth. The Oxygen present in the air helps in burning fuel which supports us in cooking food, in running industries, etc. as well as also helps in generating heat and so on. Thus there are other biological uses of air that also play a crucial role in our life such as; during respiration oxygen is inhaled into the lungs and then released into the bloodstream and oxygen is distributed in all cells of the body.

Physical Properties:

Chemical Properties and uses

a)Pain reliever: Even in pharmacological medical specialty and medicine, especially for use of anesthetics, ether has a major role to play. Methoxymethane or otherwise referred to as antitussive is a good pain-relieving drug, and is the primary ingredient in morphine. Ethyl Ether (or just ether) was one of the first anesthetics used for surgical procedures during the 1800s. However, ether is highly flammable and has been mostly replaced by other less-flammable anesthetics like nitrous oxide and halothane. Ether was once used in pharmaceutical formulations. A mixture of alcohol(ROH) and ether(ROR), containing one part of diethyl ether and three parts of ethanol, was known as “Spirit of ether”, Hoffman’s Anodyne or Hoffman’s Drops. In the United States, this mixture was removed from the medical shops at some point as it was found that there were differences in the formulation to be found between business makers, between international pharma companies, and from Hoffman’s original recipe.

Compound spirit of ether or Hoffman anodyne has a peculiar odor, which it owes to the ethereal oil. In style, it’s highly regarded, pungent, and somewhat sweetish. It should be completely vaporized by heat and insolvent of acidic reaction; and, when mixed with water, should have a somewhat milky appearance, owing to the separation of the oil.

The effects of Hoffmann’s anodyne are somehow similar to those of ether but somewhat modified by the oil of wine, so as to bring it more nearly into accordance with the category of nervous stimulants. Ether, in small doses, insufficient to disturb particularly the cerebral centers, is actually a nervous stimulant; and, were it used only by the stomach, may perhaps be ranked properly with this group of medicines; because it is rarely given through this manner for its narcotic effects. But used, because it is nowadays by inhalation, conspicuously as a cerebral stimulant, and conformist therefore closely in its effects, as therefore administered, with alcohol and opium, it could not with propriety be removed from this connection. 

Hoffmann’s anodyne is used to influence nervous stimulation in its numerous forms. Among alternative effects is that of affecting sleep cycle resulting in longer sleep hours; so it acts, circuitously on the brain as a narcotic, however merely as a general stimulant to the system, equalizing its actions, and thus removing the cause of wakefulness. From its common name, it would be purported to have extraordinary powers of relieving pain. If given in massive quantities, it might possibly produce this effect directly, as the vapor of ether does when inhaled, by rendering the cerebral centers insensitive to the frustrations with occasion pain. As commonly given, however, it doesn’t act during this manner, but only by quieting the irritation upon which the pain may depend; and, when this is beyond its powers, it is itself inoperative as an anodyne. In case of severe pain, therefore, it will occasionally afford relief; in the pains of a surgical operation, and those dependent on inflammation, or even active congestion, seldom or never in any ordinary dose. Mild spasmodic affections will quite often yield to it.
It is much used in febrile diseases to calm restlessness, and general malaise, to obviate the nervous twitching and starting that are common in children. In mild troubles of hysteria, in faintness, lowness of spirits, palpitations, etc., and in analogous affections in the male sex, Hoffmann’s anodyne is often a preferred medicine to the physician, until the extreme stage is reached when more powerful remedies need to be implemented.

Flatulent pain and gastric uneasiness can also be treated by this organic compound.
It is typically an easy, quick, economical remedy in treating nervous headache.
It might be employed, in very large doses, for obtaining those more powerful effects in spasmodic diseases for which ether itself is given; but the proportion of alcohol it contains must always be taken into account before giving the dosage to the patients.

When tincture of opium sickens the abdomen or occasions headache, the impact could generally be prevented by giving Hoffmann’s anodyne along with it.

A mild dosage of it, sometimes produces terribly pleasant effects in restlessness, in the dose of from thirty to sixty drops. It should be given in a wineglassful of water, sweetened or not as the patient may prefer. The dose is also continual each hour or 2 if needed. It is often usefully combined with a solution of sulfate of morphia, or other preparation of opium, in affections in which both medicines are indicated.

b) For Anaesthesia purpose: Diethyl ether mostly supplanted the employment of chloroform as an anesthetic due to the ether’s additional favorable therapeutic index, that is, a bigger distinction between an effective dose and a potentially toxic dose. 

 
Diethyl ether depresses the cardiac muscle and will increase tracheobronchial secretions. The anesthetic inhalation, in general, may even be mixed with different anesthetic agents like chloroform to form C.E. mixture, or chloroform and alcohol to form A.C.E. mixture, considered to be a historical anesthetic agent. But in today’s medical practices, ether is rarely used. The use of burnable ether was displaced by incombustible fluorinated organic compound anesthetics. Halothane was the primary such anesthetic developed and different presently used indrawn anesthetics, like inhalation anesthetic, desflurane, and sevoflurane, are halogenated ethers. Diethyl ether was found to have adverse side effects, such as vomiting a
nd post-anesthetic nausea. Modern anesthetic agents reduce these side effects.

Local Anaesthetic by Ether-spray,—affords good relief in hurting of superficial nerves, lumbago, chorea, spinal irritation, and in minor surgical operations it is an important method, but now displaced by Cocaine.

Nitric acid is commonly known as aqua fortis or spirit of nitre. It is represented by the chemical formula of HNO3. It is a very strong oxidizing agent and a super-strong corrosive mineral acid. It is a colourless acid but older samples will acquire a yellow cast due to the formation of oxides of nitrogen. Commercially available nitric acid is concentrated up to 68% w/w. This means that 68 grams of nitric acid are dissolved in 100 ml of water. 

Nitric acid is an important laboratory reagent used for nitration- the addition of the nitro group to an organic molecule. There are other varied uses of nitric acid in the industrial sector. Talking about its chemical structure, nitric acid is an example of a monobasic acid.

Formula: HNO₃

What is the Nitric Acid Density, Boiling Point and Melting Point? 

• Density: 1.51 g/cubic cm

• Boiling point: 83℃

• Melting point: -42℃

Areas of Application of Nitric Acid

There are many important uses of HNO3.  These are as follows-

• In fertilizers: Nitric acid is a very important compound used in the production of different kinds of fertilizers. Nitrogenous fertilizers are one of the main categories of fertilizers for example calcium nitrate, ammonium nitrate, etc. Nitric acid is used to manufacture these compounds. Nitrogen is one of the primary nutrients that is required by plants. It plays a very crucial role in plant physiology and hence plants require an excessive amount of nitrogen as compared to other elements. Hence nitrogenous fertilizers are of vital importance to agriculture and farming.

• The precursor to nitro organic compounds: Nitric acid is used for the nitration of several organic compounds. The nitro group is a very versatile functional group by which many explosives such as TNT is prepared. This group is added to aromatic compounds by using a mixture of nitric acid and sulfuric acid. 

C6H5CH3 + 3HNO3 🡪 C6H2(NO2)3CH3+ 3H2O

The above mentioned is the chemical equation for the preparation of the explosive TNT.

• Polymer synthesis: Nitric acid is the raw material for the synthesis of many chemical compounds. Polymers like polyamines and polyurethane are few compounds that essentially require nitric acid for their synthesis. Certain polymerization reactions take place only in presence of a nitric acid medium. 

• Rocket propellant: Nitric acid is used as a rocket propellant in the aerospace industry. This form of nitric acid is known as the red fuming nitric acid which is a storable oxidizer. It contains 84 % nitric acid, 13% dinitrogen tetroxide and 1 to 2% of water.

• As an oxidant: Nitric acid is a very strong oxidizing agent hence used as an oxidant. Adipic acid which is a precursor to the polymer nylon is produced on a very large scale by the oxidation of KA oil which is a mixture of cyclohexanone and cyclohexanol by nitric acid. The function of nitric acid here is to oxidize the oil to yield adipic acid. 

• Manufacture of various industrial products: Nitric acid is used for the production of various industrial products like nitrate salts, dyes, coal tar products, various drugs.

• In preparation of aqua regia: Aqua regia is a yellow fuming liquid made by mixing concentrated nitric acid and concentrated hydrochloric acid in ratio 1:3. It can dissolve noble metals like gold and platinum hence it is used in the purification of gold and platinum and also in jewellery making. 

• Nitric acid uses at home: Directly nitric acid is not used in our daily life owing to its extreme power of corrosion and harmful effects on human tissue. Instead, the products manufactured from nitric acid like various medicines, cleansers, fertilizers for the garden are used in our homes on a daily basis. Uses of nitric acid in our daily life can be said as a laboratory school reagent. Dilute nitric acid is used in the woodworks and carpentry to fabricate a maple and pine wood log for giving them an old look. Nitric acid is used in the spot test of alkaloids like LSD which is known as the colourimetric test.

• Nitric acid medical use: Nitric acid is used to prepare homoeopathic medicines through a process called potentization. There are drugs that cure throat sore and tonsillitis, mouth ulcers, piles and skin issues.

Interesting Facts About Nitric Acid

Nitric acid is produced by the process called the Ostwald process. This was discovered during the time of the first World War and was a reason behind the extension of the war. This was because Germany had no method of producing nitric acid which was essential for the production of explosives used in the artillery shells like nitroglycerin and nitrotoluene. Nitrates are available only from Guano islands in the form of droppings of fish-eating birds. Hence another method to make nitric acid was essentially required.

Nitric acid is an extremely corrosive acid and can cause irreparable burns on the skin. It burns the human tissue. It should be handled under expert supervision at school or other places. It should be kept out of reach of students. The concentrated form of the acid is usually not used for demonstration in schools as it is more corrosive as compared to the dilut
e form.

Water is a transparent, tasteless and odourless liquid that is essential for all living beings. Water has several distinct properties that are important for the sustenance of life. It is important as a solvent that helps dissolve all the solutes of the body and facilitates several metabolic processes within the human body. There are several uses of water in daily life. It helps to flush out the toxins from our bodies. It plays a critical role in photosynthesis and is released during respiration. 

Around 70% of the earth’s surface is covered with water. However, only a small percentage (around 1%) of it is suitable for human consumption. There has been an exponential rise in the global population while the supply of water has remained fairly constant. Some of the sources of water like rivers and lakes are getting contaminated due to industrial pollution and poor policymaking. 

Oceans and the frozen areas of the polar region hold a large portion of the global water content. The water cycle is a phenomenon where the water vapour created from oceans, lakes, and rivers condenses and returns to the earth through precipitation. The cycle includes evaporation, precipitation, and runoff as the transfer processes. Ponds, lakes, rivers, streams, and seas are some of the sources of water which depend on rains and the water cycle. 

Human beings need water for hydration as we regularly lose water during breathing, sweating and digestion. The amount of water that is needed depends on the climate, kind of physical activity and health status of the individual. Other living beings are equally dependent on water for their survival. For plants, the moisture content of the soil helps them to grow. 

Characteristics of Water:

• Some of the characteristics of water are:

• It is a polar inorganic compound.

• The water molecule contains 2 hydrogen atoms and 1 oxygen atom. 

• Its chemical formula is H₂O.

• The freezing point of water is 0˚C.

• The boiling point of water is 100˚C.

The Hydrologic Cycle of Water

The continuous circulation of water in the Earth atmosphere is known as the Hydrologic cycle of water. There are many processes involved in the Hydrologic cycle; the important processes that the students will learn today are evaporation, transpiration, condensation, precipitation and runoff. Now let us look at all these processes in detail. 

• Evaporation: This process involves a change of state of a substance from water to gas. The evaporation process needs the energy to take place. The source of energy could be Earth, the atmosphere, the sun, humans or any objects on the surface of Earth. For example, a human body sweats after exercise or even due to a temperature change, secreting water on the skin. The basic purpose of this process is to cause the body to use its heat to evaporate the liquid by removing the heat and cooling down the body. 

• Transpiration: This process involves the evaporation of water from plants through stomata. Stomata are connected to the vascular plant tissue and are small openings that are found on the underside of the leaves. The transpiration process is caused by the humidity in the atmosphere and the moisture present in the soil. Only 1% of the transpired water is used by the plants and the rest 90% is passed into the atmosphere. 

• Condensation: This process involves a change of water vapour present in the earth atmosphere to change to a liquid state. Clouds or dews are examples of atmosphere condensation. For example, the droplets of water that we see on cold drink bottles. The change of temperature results in the water vapour changing into liquid. Condensation does not take place because of the change of the temperature but the difference in temperature is considered that is the air and dew point temperature (Dew can be formed). Cooling causes the vapour to condense. We must have observed fog, the foggy condition is the result of the air and dew point temperature being the same. Condensation and Evaporation are two opposite processes.

• Precipitation: This process involves the particles formed by the condensation process to grow large. This could result through coalescence or collision, by the rising air and thus falls to the earth. Precipitation can be in the form of rain, snow, etc. This process is the source of freshwater that we receive on Earth. 

• Runoff: This process involves the process when the water cannot be absorbed anymore due to an excess amount of precipitation. Lakes, ponds and rivers are a few examples of runoff. Evaporation of this runoff sets the cycle all over again. 

What are the Uses of Water?

There are many different uses of water, and this life-giving resource comes in handy to accomplish everything from our daily chores to helping entire industries function. 

Domestic Uses of Water

Water is important for cooking and helps in boiling, steaming and simmering food. Water has unique properties to form solutions and emulsions which make it an effective agent to help in washing clothes, dishes, and food items. Washing with water helps in removing impurities. It is required for taking showers, brushing teeth and maintaining personal hygiene. It is used for gardening at home. Water is used in several home appliances like air coolers. Water is used to generate electricity which is consumed for domestic purposes. 

We lose the water in our bodies during breathing, sweating, and digestion. The water content of the body should be replenished by drinking regularly to avoid dehydration and other health problems. Around 1 to 7 litres of water is recommended per day to avoid dehydration

Uses of Water in Agriculture

A large percentage of water is used in agriculture annually. Agriculture requires large quantities of water to grow fresh produce and sustain livestock. It is used for irrigation, pesticide and fertiliser application, frost control and crop cooling. Proper usage of water is important to manage crop yield and productivity. Farmers should follow several water conservation strategies for sustainable agriculture. 

Plants use water and sunlight for photosynthesis and produce oxygen. Agricultural water comes from surface water (rivers, streams, open canals, ponds, reservoirs and lakes), groundwater from wells and rainwater. Water is used in all traditional agriculture methods including the cultivation of rice, wheat, sugarcane, etc. 

Water quality can be affected by rampant in
dustrialization and the illegal disposal of chemicals in water and the atmosphere. Poor water quality affects the quality of the food crop and may also cause several diseases. Water contamination is the main reason for food contamination and illnesses related to the contamination. Groundwater is a safe source of quality water.                                              

Water is used for livestock, dairies, and fish farms. 

Industrial Uses of Water 

Water is used in hotels, motels, restaurants, offices, and other commercial facilities. 

It is essential in the manufacturing and production of paper, chemicals, automobiles, steel, food, textile production, dying, etc. Power plants need a significant amount of water for cooling. 

Water is a universal solvent and hence is used to dissolve several compounds in industrial production. It is widely used as a solvent and less commonly used as a catalyst. Water vapour is also used in several industrial processes. Water is used by smelting facilities and petroleum refineries. 

Industrial uses of water are processing, diluting or fabricating a product. Rivers, canals, oceans, and seas provide simple means of transportation. There will be less friction in the water compared to land transport without any obstacles. It offers economic opportunities with an effective way to transport cargo. 

Water is a source of hydroelectricity. Dams are constructed across rivers and lakes to store water which is converted to electricity using turbines. Hydroelectricity is a renewable energy source that is used across the globe. It has reduced the dependence on fossil fuels for energy. 

Water is used in the extraction of minerals, oil, and gases. It is essential for several critical mining functions. Along with being a solvent, water is used in a steam turbine and heat exchanger. 

Medicinal Uses of Water

Water has several medical uses especially in hemodialysis and dental procedures. It is used to wash surgical tools and equipment. It is also essential for hydrotherapy. 

Contamination of water with pathogens is an important concern in the healthcare setting as the immune system is weakened in some patients. The waterborne disease can spread through direct contact, ingestion, in-direct contact, and inhalation, aspiration of water and blood contact. Water should be thoroughly treated before it is used in hospitals and clinics. Clinicians should take appropriate measures to avoid contaminating water that will be ingested by the patient. 

Top 5 Causes of Outbreaks Related to Water Contamination are:

•  Legionella

•  Giardia

•  Campylobacter

•  E. coli

•  Cryptosporidium, Hepatitis A, Mycobacterium, Norovirus, Pseudomonas, Salmonella 

Thus, pure water should be available for drinking to avoid such epidemics.