Category: Chemistry Notes PPT

Potassium Hydroxide Chemical Formula

As explained earlier, the chemical formula of potassium hydroxide or caustic potash is KOH. It is a crystalline solid with a crystal structure which is similar to sodium chloride at higher temperatures.

The chemical structure of KOH molecule is as follows:

In the above structure, the distance between K+ and OH– ions varies anywhere between 2.69 to 3.15 angstroms. 

Although KOH can exist as a crystalline solid similar to sodium chloride, but due to its high affinity to water, it usually ends up forming crystalline hydrates. The most common hydrates of caustic potash are mono, di and tetra with either 1 water molecule, 2 water molecules and 4 water molecules, respectively, attached to one molecule of potassium hydroxide.

Properties of Caustic Potash

As we explained earlier, potassium hydroxide or caustic potash has multiple uses because of a wide array of chemical and physical properties that it possesses. We have made some general references to a few of such properties in previous sections, but here we look at those in a slightly more detailed manner.

At room temperature, potassium hydroxide exists as a colourless solid which is generally translucent. Since it has a high affinity to water, its crystals also contain water molecules in varying degrees. Commercially, it is sold as flakes, pellets or powder, depending on the usage. 

As the name suggests, it also has caustic nature, which basically means it has a burning sensation and is an irritant if exposed to naked skin. It is advised to be used and handled with caution. It also has a highly corrosive nature. It can corrode metals along with living cells or tissues.

Potassium hydroxide is a hydroxide of an alkali metal. Hence, it is a strong base. In fact, it is featured among some of the strongest stable bases. The pH value of a 1m mol/L solution of KOH at standard conditions is 10.98, which is very high. 

Caustic potash is highly soluble in water as well as organic alcohols. A lot of heat is released when it dissolves in water. In organic alcohols, potassium hydroxide forms an acid-base equilibrium as below:

KOH + CH3OH ↔ CH3OK + H2O

Equation 1: Acid-base equilibrium of KOH with Methanol

It also reacts with inorganic and organic acids to form corresponding salts.

KOH + HCl 🡪 KCl + H2O

Equation 2: KOH reaction with an inorganic acid

Potassium hydroxide is used in a process called saponification to convert organic fats into soaps. A generic reaction looks as below:

It is noncombustible in nature, so it doesn’t react with oxygen. But it can react with carbon dioxide to form potassium bicarbonate.

KOH + CO2 🡪 KHCO3

Equation 4: Caustic potash reacts with carbon dioxide

Potassium hydroxide is highly stable at high temperatures. It gets converted into liquid or gaseous form before disintegrating into its constituent elements at high temperatures. Because of high thermal stability, it can be melted and cast into any desirable shape which may be required for further uses.

Uses of Potassium Hydroxide

Potassium hydroxide is used in preparing soaps by a process called saponification. It is used as a base to convert oils/fatty acids and their esters into soapy salts. Soaps with potassium salts are more soluble than those with sodium salts, and hence are also referred to as soft soaps.

Although corrosive in nature, potassium hydroxide is used in food products as a thickening agent and stabilizer. It can only be used in a certain quantity so that the food items stay safe for human consumption.

It is used as a cleaning agent. One of the most common household cleaning uses is the drain cleaner chemical, which contains potassium hydroxide. Some of the drain cleaners may also contain sodium hydroxide because of its similar nature with potassium hydroxide.

Potassium hydroxide also has medical uses. It is used to prepare clinical specimens of fungal infections in hair, skin, nails etc. It has also been found to treat plane warts well.

Due to its highly conductive nature, it is also used as an electrolyte, especially in alkaline batteries.

Potassium hydroxide is a good etching agent and is used in anisotropic wet etching of semiconductor wafers during the manufacturing of electronic chips.

It is also used to prepare other potassium products and salts such as phosphate, permanganate etc. 

Preparation of Potassium Hydroxide

Potassium hydroxide is prepared at industrial scale by electrolysis of potassium chloride solution. The process can also be referred to as chloralkali process. The reaction takes place as below:

2KCl + 2H2O 🡪 2KOH + Cl2 + H2

Equation 5: Electrolysis of KCl

Chlorine and hydrogen are byproducts of this reaction.

Though KCl electrolysis is the current method of preparing KOH, historically, it was prepared using a salt metathesis reaction of calcium hydroxide and potassium carbonate. In a salt metathesis reaction, the two reactant compounds react to form 2 new compounds as products where their respective elements or constituents exchange places. During the preparation of potassium hydroxide, this reaction takes place as follows:

Ca(OH)2 + K2CO3 🡪 CaCO3 + 2KOH

Equation 6: Salt metathesis reaction to prepare potassium hydroxide

The reaction takes place in an aqueous solution. This method of preparation is not used currently and was in use till the 19th century. Invention and widespread use of electricity replaced the old method with the current electrolysis reaction method.

This ends our coverage on the topic “Caustic potash or Potassium hydroxide”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic. If you are looking for solutions of NCERT Textbook problems based on this topic, then log on to website or download Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.

Democritus proposed that matter is made up of small units called atoms. Slowly with time, experiments and discoveries scientists proposed that atom is not the ultimate particle. It is made up of three subatomic particles called electron, proton and neutron. Protons and neutrons are found in the nucleus of the atom while electron is found in the shells or orbits around the nucleus. Electrons are negatively charged subatomic particles while proton are positive, and neutron are neutral. Structure of an atom is given below –

Charge on an Electron

Electric charge on an electron is -1.602 10-19C (or experimental value -1.602176634 10-19Coulombs). It is used as a standard unit of charge for subatomic particles. It is called the elementary charge. Symbol of elementary charge is e. The electrical charge on an electron is equal to the charge on proton, but with opposite sign. As the elementary charge is denoted by e, the electron is commonly symbolized by e–. Minus sign denotes negative charge. Charge on an electron is given below in the table in different units. 

 

Mass of an Electron

The intrinsic mass of an electron is approximately 9.109 10-31 kilograms. This mass corresponds to a rest energy of 0.511MeV, according to Einstein’s principle of mass-energy equivalence. We can define its mass in relative terms of proton as well. The mass of an electron is 1/1836 of mass of proton. Mass of electron is given in the table below in different units –

 

As we can see mass of electron is very less so it can be taken as approximately 0amu. 

Charge to Mass Ratio of Electron 

As we have already discussed mass and charge of an electron. So, now its easy to calculate the charge to mass ration of electron. 

Charge of an electron (e) = 1.602*10-19C

Mass of an electron (me) = 9.109 *10-31 kilograms

(Image to be added soon)

If we take value up to six digits after decimal, then it will be 1.758820 1011Ckg-1. 

This was brief on the topic – Electron, if you want to know more about electron or other subatomic particles then register yourself on or download learning app 6-10, IIT-JEE and NEET and get many more such articles, detailed study material and NCERT Solutions of all subjects.

A prominent “group 13” element, which is also a member of the Boron family whose electronic configuration is 1s2 2s2 2p6 3s2 3p1 is known as Aluminium. The addition of the first three Ionization enthalpies of the Aluminium, AI3+ ions can form. It usually furnishes +3 oxidation states and also is a high electropositive element which is in the case of Aluminium Oxide (Al2O3). The other type of oxidation states is +2 and +1. A transparent Aluminium oxide (Al2O3) layer protects it which forms in the air. There are physical and chemical properties of Aluminium, and its uses can also be seen.

Three Properties Of Aluminium 

To explain what are the properties of Aluminium, the 3 properties of Aluminium can be described as follows:

• The first of the three chemical properties of Aluminium is the Reaction of Aluminium with air. Aluminium metal generally does not react with air as the surface of it is covered with an oxide layer which protects the coating from the attack of air. If the oxide layer gets damaged, the exposure of the Aluminium metal can be seen which reacts with oxygen and helps in the formation of amphoteric oxide (Aluminium (III) Oxide), Al2O3.         

4Al (s) + 3O2 (l) → 2Al2O3 (s)

• The second of the three chemical properties of Aluminium is the reaction of Aluminium with acids. Mineral acids react with Aluminium to make solutions which contain liquid AI (III) ion along with the release of hydrogen gas, H2. The reaction of Aluminium with HCl releases hydrogen gas.

2Al3+ (aq) +6HCl (aq) → 3H2 (g) + 6Cl– (aq)

This is how the reaction of Aluminium with hydrochloric acid happens.

• The third of the three chemical properties of Aluminium is the reaction of Aluminium with alkalis. This reaction leads to the liberation of hydrogen gas (H2). Oxygen and Aluminium electronegativity make it possible for the Aluminium to form covalent bonds along with oxygen if Aluminium reacts with warm, sodium hydroxide solution to create a colourless solution of sodium tetrahydroxoaluminate along with the release of hydrogen gas.

2Na+ (aq) + 2[Al (OH)4]– + 3H2 (g) → 2Al (s) + 2NaOH (aq) + 6H2O

Other than the three properties of Aluminium which are chemical properties of Aluminium, there are few physical properties of Aluminium.

The 3 properties of Aluminium Which are Physical Properties, Can Be Explained:

• Aluminium is a silver type of metal with a tint that is bluish. 

• The melting point is 660°C (1,220°F), and the boiling point is 2,327-2,450°C (4,221-4,442°F).

• The density of Aluminium is 2.708 grams per cubic centimetre which is both malleable as well as ductile.

Uses Of Aluminium 

Aluminium is utilized in a tremendous assortment of items including jars, foils, kitchen utensils, window outlines, lager barrels and plane parts. This is a result of its specific properties. It has a low thickness, is non-toxic, has high thermal conductivity, has incredible corrosion obstruction and can be easily cast, machined and shaped. 

It is regularly utilized as alloy since Aluminium itself isn’t stable. Compounds with copper, manganese, magnesium and silicon are lightweight however stable. They are significant in the development of planes and different types of transport. 

The Biological Role Of Aluminium 

Other than the three properties of Aluminium which are chemical properties of Aluminium as well as physical properties of Aluminium, no such biological role can be seen. +3 soluble in the plant makes it toxic. Acidic soils are due to the reaction of Aluminium with HCl found mostly on the Earth with AI3+ release from their minerals which the crops absorb.

Solved Example

1. What happens when there is a reaction of Aluminium with HCl?

The reaction of Aluminium with hydrochloric acid produces liquid aluminium chloride, AlCl3, as well as hydrogen gas, H2.

The chemical equation which is balanced explains this single replacement reaction that is 

2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)↑

Remember that this reaction of Aluminium with hydrochloric acid will not happen when we add the piece of Aluminium to the hydrochloric acid solution. This is because the piece of Aluminium is covered by a layer of aluminium oxide, Al2O3, which protects Aluminium reacting with the water. The hydrochloric acid will need some time to work through this layer, but once it happens, the reaction will proceed faster, i.e. bubbling can be seen in the hydrochloric acid. 

 

Fun Fact

1. In more than 270 minerals, Aluminium mostly can be found.

2. It is one of the most abundant minerals on Earth after oxygen and also silicon.

3. Aluminium as a global scale is one of the most used metals which do not contain iron.

4. Aluminium reflects almost 98% of infrared rays and 92% visible light.

5. Currently, Australia can be said as the largest producer of Aluminium.

Chlorobenzene is a compound that has a chemical formula of C6H5Cl. This liquid is flammable and is also known as a common solvent. Chlorobenzene is commonly used to manufacture chemicals. The main use of this compound is done to produce commodities that include herbicides, rubber, and any other dyestuffs. It is also used as a solvent in various industrial applications and laboratories. It is nitrated to produce a mixture that includes 2-nitrochlorobenzene and 4-nitrochlorobenzene on a huge scale. Then, the mononitro chlorobenzenes are turned into 2-nitrophenol and other elements of chloride. Sometimes, many industries convert Aniline to chlorobenzene to use it as an agent for all the alkenes produced.

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How to Convert Aniline to Chlorobenzene?

The process to convert Aniline to chlorobenzene is quite challenging. You will have to use NaNO2/HCl to convert Aniline to benzene diazonium chloride. It then converts to chlorobenzene as the presence of CuCl affects the entire reaction. This type of reaction is called Sandmeyer Reaction.

The Formula For the Reaction is as follows:

C6​H5​NH2​NaNO2​/ HCl​C6H5​N2​ClCu2​Cl2​​C6​H5​C

The entire process is completed in two steps. The temperature at which the reaction occurs stands at 0 degrees to 5 degrees centigrade.

When it comes to Sandmeyer Reaction, there are many types of reactions. You can react with benzene diazonium chloride with other solvents, including CuCI, CuCN, and many more. It forms chlorobenzene, benzonitrile, and many more.

How Can You Convert Benzene to Chlorobenzene?

The process of benzene to chlorobenzene conversion is pretty simple. You will first have to react to Benzene with Chlorine. However, you will have to ensure that a catalyst can replace the Hydrogen atoms with chlorine atoms. The room temperature is suitable for this type of reaction. You can take aluminium, chlorine, and iron in the form of catalysts. 

However, it is not advised to take iron as a catalyst because, during the reaction, the particles get permanently altered. Iron has the ability to react with chlorine and form FeCl3 (Iron Chloride).

Also, you can take iron chloride in the form of a catalyst and make it behave like Aluminium Chloride (ALCL3). Then, chlorobenzene is formed when this type of reaction comes in contact with aluminium chloride.

The Process to Convert Chlorobenzene to Aniline

To convert Chlorobenzene to Aniline, you can prepare it commercially with the help of a catalyst, Nitrobenzene. You can also use ammonia on the produced chlorobenzene. All you have to do is reduce Nitrobenzene by carrying out a reaction in aqueous acid with the help of iron borings. As Aniline is considered a weak base, it tends to form salts when you dilute it in mineral acid.

How Can You Convert Chlorobenzene to Benzene?

You can convert chlorobenzene to benzene in three different steps altogether. You can start the reaction by reacting HNO3 with H2SO4 that will form Nitrobenzene. Then, you can reduce it by forming a reaction of Nitrobenzene and Sn+HCL, Fe+HCL, or H2/Pd to produce Aniline. After the reaction is completed, you can then add NaNO2+HCL to the reaction that will form benzene Diazonium Chloride. After that, you can react with Sandmeyer’s Reaction (CuCl) or Gatterman Reaction (Cu Powder). This will form Chlorobenzene.

How Can You Obtain Mono Chlorobenzene?

When you dissolve or suspend Aniline with cold aqueous mineral acid and treatment with sodium nitrite, then a diazonium salt comes into existence. This salt has to be treated with cuprous bromide to form mono chlorobenzene. 

When you substitute chlorine at any given spot, then you will see that six carbons remain constant. Therefore, only one possible benzene is formed. 

How Can You Prepare Chlorobenzene From Aniline?

You can prepare chlorobenzene from Aniline with the help of Sandmeyer Reaction. You can fit the reaction with diphenyl and extract it from chlorobenzene.

Here is a Step-By-Step Process to Prepare Chlorobenzene From Aniline:

Step 1: Sandmeyer Reaction: It is a chemical reaction that you can use to synthesize the aryl halides from the diazonium salts by using agents of copper salts and catalysts. 

Step 2: You can follow a two-step reaction that includes converting benzene diazonium chloride by utilizing the Sodium Nitrate solutions and aqueous hydrochloric acid. Then, you can react to the benzene diazonium with cuprous chloride to form chlorobenzene.

A chemical compound is a chemical substance that has molecules with two or more elements. Matter consists of atoms of various elements. Elements either exist as pure forms or in a combined form. The combined form is known as a chemical compound. A pure element is made up of atoms that are found in that element. Each element gets its characteristic properties due to the characteristic nature of the atoms that comprise that element. For instance, atoms of iron are very different from atoms of gold. Each atom has its symbol which is often an abbreviation of its name or its name in Latin. 

Chemistry involves studying how atoms of various elements combine to form compounds. Ethanol for instance is formed from the elements carbon, hydrogen, and oxygen. It contains specific ethanol molecules. The chemical formula of ethanol C₂H₅OH indicates the types and the numbers of atoms that are present in the compound. Water which has a chemical formula H₂O consists of 2 atoms of hydrogen and one atom of oxygen. Salt or sodium chloride is a compound that has sodium and chlorine in an equal ratio. It has sodium ions that are positively charged and chlorine ions that are negatively charged. 

From these examples, we can get a basic classification of compounds- covalent or molecular compounds and ionic compounds, compounds that comprise molecules are called molecular compounds, and compounds that comprise ions are called ionic compounds. 

Classification of Pure Substance

Matter can be categorized into various categories. In chemistry, the category that we begin from is that of pure substance and mixtures. A pure substance is a chemical material that has a consistent composition throughout. All parts of a pure substance will have the same chemical properties regardless of where it is obtained. Pure substances are further classified as elements and compounds. Elements are chemicals that cannot be broken down into smaller units. While substances that can be broken down into their constituent units are called compounds.  

Classification of Metal Carbonyls

Metal carbonyls are a class of organometallic compounds. They are of two types: mononuclear carbonyls that have one metal atom per molecule and polynuclear carbonyls that have two or more metal atoms per molecule. 

Classification of Alkyl Halides

Alkyl halides or haloalkanes are compounds in which hydrogen atoms in an alkane are replaced by atoms from the halogen family such as chlorine, fluorine, etc. Haloalkanes are of 3 types primary, secondary and tertiary. In primary haloalkanes, the carbon connected to the halogen on one end is attached to a single alkyl group on the other end. In secondary, the carbon connected to the halogen is connected to two same or different alkyl groups. In tertiary alkyl halides, the carbon atom is connected to three same or different alkyl groups. 

Classification of Carboxylic Acid

Carboxylic acids are those organic compounds in which the carbon atom is connected to the oxygen atom by a double bond and a hydroxyl group by a single bond. Carboxylic acids are categorized as aromatic, unsaturated, and saturated aliphatic, amino acids, keto and hydroxy acids, and polycarboxylic acid. 

Classification of Organic Compounds

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1. Open Chain Compounds: Also called acyclic or aliphatic organic compounds, they consist of chains that may be straight or branched. 

2. Closed Chain Compounds: Also called alicyclic or ring organic compounds, they consist of atoms of carbon that are joined to each other in a ring structure. If the chain also contains atoms that are not carbon then the ring is heterocyclic. 

3. Aromatic Compounds: Aromatic compounds are organic compounds with a unique set of properties. They also gave a ring structure. They can also have more than one atom in the ring. 

Classification based on the functional group: An atom or a set of atoms that are combined in a particular way to an organic compound is called a functional group. These groups impart specific chemical properties to the compounds they are joined to. Some examples of functional groups are: -OH,-COOH et al.

4. Homologous Series: A series of organic compounds where each part has the same functional group that imparts its special characteristics. For instance: alkanes, haloalkanes, amines, etc.  

Fun Fact

An organic compound was first synthesized from inorganic substances by the German chemist Friedrich Wöhler in 1828. This discovery was accidental. He synthesized urea by mixing the salts silver cyanate and ammonium chloride. From this result, he proposed that atoms used different methods of arranging themselves into molecules and that the characteristics of these molecules are based on the molecular structure. Other chemists followed suit and by the 1860s, the notion that some magical “vital force” was required for the formation of organic compounds was debunked. 

This article deals with the different aspects of coal like its properties, chemistry, types, and distribution in the world. But before going into the various aspects of coal, let us find out “what is coal”. Coal is a sedimentary rock that is blackish or brownish-black in colour and is developed from start rock also referred to as coal seams. This is assumed to have developed from the residue of the algae plants. Coal is composed of a maximum amount of carbon with other organic elements chiefly hydrogen followed by sulphur, oxygen, and nitrogen. 

When the dead and decayed matter of plants and animals undergo heat and pressure of deep burial for millions of years, they convert into peat and finally into coal. Wetlands are the hub of coal, and therefore, the region is also referred to as coal forests. It covers much of the topical land of the Earth during the late Permian and Carboniferous times. But most of the coal that is found today has been studied to be much younger than the times mentioned, and therefore, it is assumed that the coals have originated from the matters of the Cenozoic and Mesozoic eras. 

Coal rock is always primarily preferred as fuel. Though coal has been in use for thousands of years, its usage was limited until the industrial revolution began. With the invention of the steam engine, the usage of coal has abruptly increased. In 2016, coal made up a quarter of the total primary energy of the world and one-fifth of the electrical energy required by the world. Some of the industrial applications like that of the formation of iron and steel require the burning of coal. 

Permanent death and illness are caused by the extraction and use of coal. It is an anthropogenic source of carbon dioxide that contributes largely to climate change, and thus, the increased use of coal affects the environment adversely. In the year 2020, with the burning of coal, about 14.5 billion tonnes of carbon dioxide was generated around the globe. It contributes to 25% of the greenhouse gas emissions and 40% of the total fossil fuel emissions. China is the largest importer and consumer of coal. 

Formation of Coal

Coalification is a process in which dead matters like plants and vegetation convert into coal over a prolonged period of time. In the past geological times, the Earth was covered with dense forests, especially in the wetland areas. Now the dead plants in these areas were prevented from decomposition and oxidation by the acidic water and mud. This results in the formation of peat. Now, the coalification process started when the bogs accumulating the peats trapped the carbon in large amounts that were eventually deeply buried by the sediments. Now, over millions of years of pressure and heat resulting in the escape of the water, carbon dioxide and methane, and the matter were left with carbon content. The gradation of the coal depends on the amount of heat and pressure the dead matter underwent to convert into coal. Thus, Lignite is formed under relatively mild conditions; sub-bituminous, bituminous, and anthracite coals are formed under high temperature and pressure. 

Temperature is one of the prime factors that are most important as compared to other factors like pressure or even the time of burial. Sub-bituminous coal can be formed at a very low temperature of 35℃ to 80℃ while anthracite is formed under a very high temperature of at least 180℃ to 245℃. Also, favourable geology does not only contribute to the formation of coal but other factors like the presence of oxygen also contribute to the high coal deposition. Thirty per cent of the wildfires were contributed by the presence of high oxygen levels in the atmosphere resulting in the formation of charcoal. The nature of the Carboniferous forests and promote plant growth are the contributors to the high level of carbon dioxide.

 

How is Coal Obtained?

Now that we know how coal is formed, it is essential to understand: how do we get coal? Coal is extracted by different kinds of mining activities on the Earth’s surface. The most common ones are surface mining and underground mining. Surface mining is done when coal is less than 200 feet below ground level. In this process, mineworkers have to remove all kinds of rocks and soil-forming the top layer. It is cheaper than underground coal mining. There are three types of surface mining – strip mining, where explosives are used to remove the top layers; open pit mining when a pit is dug; and MTR mining where a whole mountain summit is destroyed. Underground mining is performed when the coal is deeper than 300ft below ground level. Coal mine workers have to carry out mining activities then. 

Properties of Coal

The physical properties of coal are as follows:-

1. The Density of Coal: The degree of mineral impurity and the rank of the coal determine the relative density for the specific gravity of the coal. In order to determine the properties of the composites and the blend, it is very important to have a thought knowledge of the density of each coal. For the conversion of the resources into reserves, the density of the coal seam is necessary. The loss of weight of the sample in water determines the relative density. This can be achieved by using finely ground coal as bulk samples get white porous in nature. It is important to however preserve the white space when measuring the specific gravity so as to determine the in-place coal tonnage.

2. Particle Size Distribution: The rank of the coal determines the particle size distribution of the coal which in turn determines the brittleness, and the handling, crushing and milling it has undergone. Generally, a certain size of coal is required for the furnace and the coke oven and therefore, its crushability needs to be determined and its behaviour quantified.

The chemical properties of coal are as follows:-

1. Moisture: As all the coals are mined in wet conditions, thus the moisture content in the coal is an important factor. Groundwater and other extraneous moisture is known as adventitious moisture and can easily be evaporated. The coals trapping the moisture in itself is known as inherent moisture and undergoes quantitative analysis. In coal, moisture may occur in four forms, namely:

• Surface moisture is the water held on the surface of the coal.

• Hygroscopic moisture is the water held by the microcapillary within the microfractures of the coal.

• Decomposition moisture is the water that is held within the decomposed organic matter of the coal.

• Mineral Moisture is the water that comprises part of the crystal structure of hydrous silicates such as clays.

Thus, the total moisture content is determined by the total mass of the untreated coal minus the total mass of the treated coal once the sample is analysed. This is achieved by:-

• Heating the coal with Toluene. 

• Within a nitrogen atmosphere, the drying is done in minimum
  -free space over 150℃. 

• Drying in the air at 100℃ to 105℃ and then the loss of mass is analysed.

2. Volatile matter: The component of the coal except for moisture is referred to as the volatile matter in coal which is liberated at high temperature in absence of air. It is usually an amalgamation of long and short-chain hydrocarbons and aromatic hydrocarbons along with sulphur. In order to evaluate the absorption application of activated carbon, volatile matter comes into play. Under rigid control standards, the volatile matter of the coal is determined.

3. Ash: The non-combustible residue that is left after the coal has been burnt is known as ash. After the carbon, oxygen, sulphur, and water have been driven off, during conversion, the bulk matter that is left behind is represented by ash. The determination of the percentage of ash is very simple. It is evaluated when the coal is thoroughly bonded and is expressed as the percentage of the original weight. It also gives a fair idea about the nature of coal. The air-dried basis on the oven-dried bases is the two ways of determining the ash content. The difference between the two processes is determined after the entire moisture in the coal has been expelled. 

4. Fixed Carbon: The fixed carbon can be found determined as the carbon which is left after the entire volatile materials are driven off. This is different from the ultimate carbon content of the coal because some carbon is lost in hydrocarbons with the volatiles. To estimate the amount of coke that would be either from a sample of coal, fixed carbon is taken into consideration. When the mass of volatile is removed, it is only then the fixed carbon is determined. Therefore, it is determined by the volatile test from the original mass of the coal sample.

Types of Coal

Coal is divided into four main types and these are anthracite, bituminous, sub-bituminous, and lignite. The ranking of the coal is done by the amount and the type of carbon that is present in the coal and its ability to produce heat when it is burned. The rank of the coal deposit determines the amount of pressure and the heat that has acted on the dead and decayed matter over a prolonged period of time. 

• Anthracite: It has the highest heating value of all the other coal types as it contains about 86–97% carbon. It summed up to less than 1% of the coal mined in the USA in the year 2020. Northeastern Pennsylvania and the United States are the two major anthracite coal mines in the world. In the United States, anthracite coal mines are generally used for the metal industries.

• Bituminous: The carbon content in bituminous coal is 45–86%. It is the most abundant type of coal that is found in the United States that accounting for about 44% of the total production of coal in the USA in 2020. In order to generate electricity, bituminous coal is used as it is an important fuel and raw material for making coking coal. 

• Sub-Bituminous: The carbon content in sub-bituminous coal is about 35–45% and it has a lower heating value than bituminous coal. In the United States, a total of 46% of the coal production in 2020 was sub-bituminous among which 88% of it was produced by Wyoming and 8% was in Montana. The remaining was produced in Alaska Colorado and New Mexico.

• lignite: The carbon content in lignite coal is about 25–35% and has a low energy content among all the coal types known. Lignite has a high moisture content which contributes to its low heating value. Only 9% of the lignite coal was mined in the USA in the year 2020 among which 54% was mined in North Dakota and 39% was mined in Texas. Another 7% was in Louisiana Mississippi and Montana.

Under suitable conditions, as geological processes apply pressure to dead biotic material over time, its metamorphic grade or rank increases successively into:

1. Peat, a coal precursor.

2. Lignite, or brown coal, the lowest rank of coal and the most hazardous to one’s health, is almost solely utilised to generate electricity.

3. Jet, is a polished form of lignite that has been utilised as a decorative stone since the Upper Palaeolithic period.

4. Sub-bituminous coal, which has qualities that fall in between lignite and bituminous coal, is largely employed as a fuel for steam-electric power generation.

5. Bituminous coal is a solid sedimentary rock that is normally black but can sometimes be dark brown and has distinct bands of bright and dull stuff. It is principally utilised as a fuel in the production of coke and in the manufacture of steam-electric power. In the United Kingdom, it’s known as steam coal, and it was once used to generate steam in steam locomotives and ships.

Uses of Coal

• Coal is a very widely used natural resource because of its unique characteristics.

• Because of its affordability, it is used in several countries for electricity and power generation. 

• Generally, powdered coal is used to create steam, which in turn generates electricity with high pressure. 

• Coal also serves as a raw material in the making of several things like steel and iron, which we use in our everyday lives. 

• Coal is available easily in countries like India and China and is used by many households, especially in rural areas, for activities like cooking. 

• Electricity Production: Coal is commonly used in thermal power generation, which aids in the generation of energy. Powdered coal is burned at a high temperature, turning water into steam in the process. In a strong magnetic field, this steam is used to turn turbines at high speeds. Then, and only then, is electricity generated.

• Steel Manufacturing: Coal is used indirectly to create steel in the steel industry. Coal is baked in furnaces to produce coal coke in this process. Manufacturers utilise coal coke to smelt iron ore into iron and make steel after this is generated. In the meantime, ammonia gas is recovered from coke ovens and utilised to make nitric acid, ammonia salts, and fertilisers.

• Industries: Coal is used in a variety of sectors to make a variety of products. Cement, paper and aluminium manufacturing, chemical and pharmaceutical manufacturing are just a few of the industries that use coal. Chemical businesses rely on coal for a variety of raw materials such as b
  enozle, coal tar, sulphate of ammonia, creosote, and so on. The majority of industries rely on coal as a source of energy.

Disadvantages of Coal

Coal has a set of disadvantages: coal mining accidents, coal pollution, etc. There are a large number of accidents that take place in coal mines because it is a dangerous and challenging activity involving heavy equipment. Moreover, coal emissions are very harmful to human beings, especially to the lungs. Coal pollution is widespread in areas that lie near coal reserves. When coal is burnt, it releases carbon dioxide in vast quantities, which is harmful to human beings. Moreover, coal is a non-renewable and exhaustive natural resource which implies that we should not depend on it for everyday activities. Coal is also one of the biggest contributors to global warming today. 

 

Coal Distribution in the World

The distribution of coal across the world is as follows:-

1. Most of the coal fuel of Russia that is trapped in the Siberian Region is unexplored.

2. The Carboniferous coal that helped us become a leading industrial nation came from two places namely great lakes and Appalachian wetlands. 

3. The coal reserves that have made Germany the leading industrial superpower of Europe are in Ruhr and Rhineland which are coupled with rich iron deposits.

4. From the coal reserves of South Wales auction Manchester and Liverpool acceptor England also benefited immensely as the industrial revolution began here mainly due to the rich reserves of the coal.

5. In South America, Brazil is the leading producer of coal. Most of the coal goes into power generation and the axis produced is imported by China.

6. The highest producer of coal in Australia and most of its course is exported either to Japan or China. Australia is famous for its rick coking coal deposits. Australia exports this coking coal mainly to India.

7. As the quality of the coal in China is very poor, thus it imports metallurgical grade coal from Australia.

8. The only region in Africa that has an abundance of coal reserves in South Africa.