Category: Chemistry Notes PPT

Define the Term Isotope?

Isotope definition or isotope meaning can be given as the chemical element variants that possess the same count of electrons and protons but with a different neutron count. In other terms, isotopes are the variants of elements that vary in their nucleon numbers because of the difference in their respective nuclei’s total neutron number. For example, carbon-12, carbon-13, and carbon-14 are all the isotopes of carbon. Carbon-12 comprises a total of 6 neutrons, carbon-13 contains a total of 7 neutrons, and Carbon-14 comprises a total of 8 neutrons.

Representation of Isotopes

Isotopes can be majorly represented in 2 different ways, which are given as follows:

By writing the name of the element followed by a hyphen and the mass number of the isotope. For example, uranium-235 and uranium-239 are two different isotopes of the element uranium.

Following the AZE notation (which is also known as the standard notation). This involves writing the symbol of an element and prefixing the atomic number in subscript and the mass number in superscript. For example, the uranium-239 isotope can be represented as 23992U, whereas, uranium-235 isotope can be represented as 23592U.

Determining the Neutron Number in an Isotope

The total neutron number present in an isotope nucleus is determined by subtracting the element’s atomic number from the mass number of the isotope. As an example, the atomic number of carbon is 6, and the 12C isotope of carbon contains a mass number of 12. Thus, the total neutron number present in the carbon-12 isotope is equal to 6.

Stable Isotopes, Radioactive Isotopes, and Primordial Isotopes

• A few isotopes contain unstable atomic nuclei that experience radioactive decay. These specific isotopes are radioactive in nature and are, thus, called radioisotopes (otherwise radionuclides). A few examples of the radioactive isotopes can be given as chlorine-36, uranium-235, uranium-238, and carbon-14, tritium (hydrogen-3).

• Primordial nuclides are the ones that existed because of the solar system formation. Out of 339 naturally occurring isotopes on Earth, a total of 286 are known to be the primordial isotopes.

• A few isotopes are known to have extremely long half-lives (in the order, hundreds of millions of years). Such types of isotopes are commonly known as either stable isotopes or stable nuclides. Some common examples of stable nuclides are given as oxygen-16, oxygen-17, oxygen-18, carbon-12, and carbon-13.

Comparison Between the Isobars and Isotopes

An isotope is described as a variation of an element that possesses a similar atomic number but with a different mass number. A group of isotopes with any element will always contain a similar number of electrons and protons. Moreover, they will vary in the number of neutrons held by their respective nuclei. One example of a group of isotopes is given as hydrogen-1 (so-called, protium), hydrogen-2 (so-called, deuterium), and hydrogen-3 (so-called, tritium).

On the other side, isobars are described as the chemical species that contain a similar number of nucleons, with different atomic numbers. The isobar groups will differ in the number of protons, in the atomic number, the number of neutrons, and the number of electrons. However, they will always contain a similar number of nucleons. Thus, the sum of the number of neutrons and the number of protons will always be the same in an isobar group. An example of an isobar group is given by argon-40, chlorine-40, sulfur-40, potassium-40, and calcium-40.

To simplify more, isotopes hold similar atomic numbers but different mass numbers. On the other side, the isobars contain similar mass numbers but with different atomic numbers.

Applications of Isotopes

• One of the important applications of isotopes is given in the determination of the isotopic signature of the element samples through isotope analysis. In general, this is done via the process of isotope ratio mass spectrometry.

• The chemical reaction mechanism can be determined using isotopic substitution. The change in the rate of reaction can be measured on the basis of the kinetic isotope effect.

• Isotopes are also used to determine the concentration of several substances/elements via isotope dilution.

An Isotope of an Element

The isotope of an element can be described as one of the many variants of the specific chemical element that carries a similar number of electrons and protons as the atomic number of the element but contains a variable number of neutrons when compared to the other variants (isotopes) of the element. Alternately, isotopes can be defined as variants of elements that differ in their nucleon numbers because of the difference in the total number of neutrons in their respective nuclei.

Isotopes of Hydrogen

The three isotopes of hydrogen can be listed as follows.

• Hydrogen-1 or Protium  

This isotope of hydrogen holds 1 electron, 1 proton, and zero neutrons.

• Hydrogen-2 or Deuterium 

This isotope of hydrogen holds 1 electron, 1 proton, and 1 neutron.

This isotope of hydrogen holds 1 electron, 1 proton, and 2 neutrons. It should also be noted that this isotope of hydrogen is radioactive.

Krypton could be considered as a colourless, odourless, tasteless inert gas that happens to be in trace amounts within the atmosphere and is usually used with different rare gases in fluorescent lamps. With rare exceptions, krypton can be more or less considered chemically inert.

Around 1ppm of Krypton is found in the air of the earth. But the concentration of this gas varies in the atmosphere depending on the planet. For example, the concentration of this gas is really less in the atmosphere of the neighbouring planet, Mars. It is about 0.3ppm. Brilliant green and orange spectral lines are its identifying feature. The spectral line for this inert gas can be very easily produced and a couple of the spectral lines produced are found to be extremely sharp. The mostly used spectral line is that of the isotope Kr-33 that produces sharp orange-red lines. 

Characteristics

Krypton is characterised by many sharp emission lines (spectral signatures) the strongest being inexperienced and yellow. Krypton is one in all the products of metallic element fission. Solid inert gas is white and encompasses a face-centred cubical form crystal structure, that could be a common property of all noble gases (except atomic number 2, that encompasses a polygon compact crystal structure).

 

Krypton, just like the different noble gases, is employed in lighting and photography. Krypton light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single spectral line. Krypton fluoride also makes a useful laser medium. From 1960 to 1983, the official length of a metre was outlined by the 605 nm wavelength of the orange spectral line of krypton-86, as a result of the high power and relatively simple operation of inert gas discharge tubes.

Isotopes

Some Additional Facts

Krypton was discovered in 1898 by Scottish chemist and physicist Sir William Ramsay (1852-1916) and English chemist Morris William Travers (1872-1961). Along with it, three other noble gases were also discovered. It was produced while the liquid air was being allowed to evaporate. Three of the noble gases discovered on that day include—krypton, xenon, and neon. The term noble gas belongs to elements in Group 18 (VIIIA) of the periodic table. These gases are called by the name “noble” because they remain unaffected even by the presence of any other chemical and never undergo any reaction under normal conditions. Until the 1960s, no compound of these gases was discovered.. Due to their inactiveness, they were given the name inert as well.

Naturally occurring inert gas in the Earth’s atmosphere, this inert gas consists of 5 stable isotopes, and one atom (78Kr) with such an extended half-life (9.2×1021 years) that it may be thought-about stable. (This atom has the second-longest best-known half-life among all isotopes that decay has been observed; it undergoes double negatron capture to 78Se).Again additionally, regarding thirty unstable isotopes and isomers are best-known. Traces of 81Kr, a cosmogonic nuclide created by the ionising radiation irradiation of 80Kr, conjointly occur in nature: this atom is hot with a half-life of 230,000 years. Krypton is extremely volatile and doesn’t keep in resolution in near-surface water, however, 81Kr has been used for chemical analysis of previous (50,000–800,000 years) groundwater.

85Kr is associated with inert hot inert gas with a half-life of 10.76 years. It is created by the fission of uranium (U) and polyurethane (Pu), like in nuclear bomb testing and nuclear reactors. 85Kr is free throughout the reprocessing of fuel rods from nuclear reactors. As a result of the convective mixing in the North Pole, the concentration of this inert gas is found to be 30 percent more in this pole as compared to the South pole.

Physical Property

Chemical Reactivity

With no difference with other noble gases, krypton is highly chemically unreactive. But prior to the 1960s, no noble gas compounds had ever been synthesized. But the manufacturing of xenon followed by formation of Krypton difluoride (KrF2) marked the beginning.

Kr + F2 → KrF2 (under extreme conditions)

Compounds with krypton bonded to atoms except fluorine have also been later manufactured.

KrF2 reacts with B(OTeF5)  producing an unstable compound, Kr(OTeF5)2, with a krypton-oxygen bond.

KrF2 reacts with HC≡NHHC≡NH+[AsF−6] below −50 °C to produce the cation HC≡N–Kr–FHC≡N–Kr–F+.

Various crystals of Krypton binary compound (Kr(H2)4) are often produced at pressures higher than five GPa. Pa=Pascal

Natural Occurrence

Earth has preserved all of the noble gases that were a gift at its formation except noble gas. Krypton’s concentration within the atmosphere is around 1 ppm. It is often extracted from the air by the process of fractional distillation. the quantity of inert gas in the space is not confirmed, because the measurement is derived from meteoric activity and solar winds

Uses and Applications

Krypton is employed in some photographic flashes for prime speed photography. Krypton gas is additionally combined with different gases to create lucent signs that glow with a bright greenish-yellow light-weight.

Krypton is mixed with an element in energy economical fluorescent lamps, reducing the facility consumption, however conjointly reducing the sunshine output and raising the value. 

The colored neon tubes found in advertising boards on roadsides are mostly krypton based. Within the red spectral line region this inert gas produces much bright light power as compared to neon and thus, during laser shows the red lasers used are mostly krypton lasers along with a mirror that selects the specific red spectral line for emission of the laser.

The krypton halide optical device is vital in nuclear fusion reaction energy analysis in confinement experiments. The optical device has a beam of light uniformity, short wavelength, and also the spot size is varied to trace the imploding pellet.

In experimental high energy physics, liquid krypton is employed to construct quasi-homogeneous magnetic attraction calorimeters. A notable example is the measuring instrument of the NA48 experiment at CERN containing twenty-seven tonnes of liquid krypton. This usage is rare since liquid inert gas is comparatively less expensive.

The conserved spark gap assemblies in detonation exciters in some older jet engines include a little quantity of krypton-85 in order to offer steady ionisation levels and uniform function.Krypton-83 has application in resonance imaging (MRI) for imaging airways. In explicit, it permits the specialist to differentiate between hydrophobic and hydrophilic surfaces containing an airway.

Although it has the potential to be used in Computed Tomography (CT) to assess regional ventilation, its anaesthetic properties limit its fraction within the respiratory gas to thirty-fifth. A breathing mixture of 30% xenon and 30% krypton can be compared to effectiveness to a 40% xenon fraction, in the meantime also avoiding the unwelcomed impacts of the high partial pressure of xenon gas.

Krypton-85, one of the metastable isotopes of this inert gas, is employed in the medical specialty for respiratory organ ventilation/perfusion scans, wherever it’s inhaled and imaged with a gamma camera.

The isotopic variety Krypton-85 mixed in the atmosphere has also been exploited to figure out the nuclear fuel reprocessing facilities in countries like Pakistan and North Korea. When discovered during the time of the early 2000s, it was largely believed that they were implemented to produce weapons-grade plutonium. It also serves the purpose of insulating gas between the sheets of glasses in the window pane.

Side Effects

Impact of Krypton on Health:

Inhalation: Krypton has a narcotic potency seven times more than air, and breathing an atmosphere of 50% krypton and 50% natural air (as might happen in the locality of a leak) may lead to necrosis in humans which is almost similar to breathing air at four times atmospheric pressure. This can be compared to scuba diving at a depth of 30 m (100 ft) and may harm anyone breathing it. Along with that, the mixture would have only 10% oxygen as compared to the normal 20% and may result in hypoxia.

This inert gas has been recognized as a simple asphyxiant. Inhalation in excessive concentrations may result in dizziness, nausea, vomiting, loss of consciousness, and under extreme circumstances, even death. If the oxygen concentration is low in the air exhaled with Kr in it, unconsciousness and death may occur in seconds without warning.

Symptoms: Rapid respirations and air hunger are the first appearing symptoms. Mental alertness gets gradually weakened, and muscular coordination is disturbed. Later on in the stage, all sensations start getting depressed. Emotional instability may also appear and fatigue will accompany these symptoms. These may be followed by nausea and vomiting, prostration and loss of consciousness, and finally convulsions, deep coma, and death.

Environmental Effects of Krypton

Krypton is a rare atmospheric gas and is being considered as such is non-toxic and chemically inert, but at extreme cold temperature (-244oC) it will freeze organisms on contact, but no long term environmental side effects are anticipated.

Things to be considered before disposal of the gas:

The gas should not be disposed of anywhere except in a well-ventilated outdoor location which is far away from residential places or places where the human can go on a regular basis. No residual gas should be disposed of in compressed gas cylinders.

Why Must We Know about Krypton?

Krypton is used commercially for a lot of purposes. It is used in energy-saving fluorescent lights and in high-speed photography.  Krypton is almost thrice the weight of air. It is colourless, odourless and also tasteless. Krypton is inert in nature. All those students who wish to take up Chemistry need to know about this gas. They will find it useful in the higher classes if they get their basics strong at a junior level. Knowing about this element becomes all the more important for those individuals who will be pursuing Chemistry or science-related research later on. Students who wish to sit for competitive exams so as to get done with their engineering also need to know about Krypton. A platform like makes it easier for all students to know about this element as it has relevant material on the same.

How helps Students by Providing Material on Krypton in Chemistry

happens to be India’s topmost e-learning platform that is utilised by students from all over the country for the purpose of studying well. It has ample study material on Krypton for the students to read from.  They can check out Krypton | Properties, Uses and Application of Krypton Element to understand more about the gas. This page has a lot of relevant stuff on the gas which will assist all Chemistry students.

The process of leaching is used to extract the substances from the solids. This process is carried out when the given substance is allowed to dissolve in a liquid. It is carried out either through a natural process or industrially.

The leaching process shows the release of both the organic as well as the inorganic radionuclides or contaminants from a solid-state to a liquid state when they get influenced by different processes like mineral dissolution, complexation, and desorption.

The process of leaching is known to be a universal process in which water tends to leach the material components that come in contact with it. This can be its surface or its interior depending on how porous the material is.

The ore of the given metal can be concentrated using this process when a chemical reaction is caused with the help of a reagent that would eventually lead to the ore getting dissolved and the impurities undissolved. 

Leaching Process Examples

The leaching process example includes the leaching of bauxite or Al₂O₃ . 2H₂O with the concentrated and heated sodium hydroxide. The concentrated NaOH here tends to dissolve the aluminium present in the given bauxite, while on the other hand, the impurities like SiO₂, TiO₂, and Fe₂O₃ do not get dissolved. The chemical reaction of this leaching process is given as follows.

[ Al_{2}O_{3} . 2H_{2}O + 2NaOH rightarrow 2NaAlO_{2} = 3H_{2}O ]

Another example of the process of leaching is leaching of the noble metals like silver and gold in the presence of the dilute aqueous solutions of either potassium cyanide or sodium cyanide in the presence of air.  The chemical reaction for this process of leaching for silver is given below.

[ Ag_{2}S + 4 NaCN rightarrow 2NaAg(CN)_{2} + Na_{2}S ]

The leaching process also causes the loss of nutrients that are present in the soil because of heavy rainfalls. 

Advantages and Disadvantages of Leaching Process

Advantages of Leaching are as Follows.

1. The leaching process is easier when it comes for the execution.

2. It is not a harmful process in comparison to the other pyrometallurgical methods.

3. It does not lead to any sorts of gaseous pollutants.

Disadvantages of Leaching are as Follows.

1. The residual liquid waste that is generated from the leaching process is highly acidic in nature.

2. The effluent of the leaching process is toxic.

3. The efficiency of the leaching process is entirely dependent on temperature.

Types of Leaching Processes in Metallurgy

The different kinds of leaching processes which are used in industrial purposes for metallurgy are given below.

1. Heap Leaching: It refers to a process which extracts uranium, copper and many other precious metals from their ores.

2. In-situ Leaching: It is a process which recovers uranium and copper.

3. Tank Leaching and Vat Leaching: They are the processes in which the ores are to be placed in vats or large tanks that consist of the leaching solutions. These processes are used for the extraction of the metals from their ores.

Leaching Process

Leaching is the process of releasing solid material constituents into a contacting water phase. Although some species may pose a greater environmental risk than others, the leaching process is indiscriminate, meaning that all constituents (e.g., major and minor matrix components, as well as inorganic, organic, and radionuclide contaminants) are released through a common set of chemical processes that include mineral dissolution, desorption and complexation, and mass transport processes. These events, in turn, are influenced by a variety of factors that can affect the rate and degree of leaching. These are some of the aspects to consider:

• Chemical and physical responses within the body

• external stressors imposed by the environment

• Physical deterioration of the solid matrix as a result of erosion or cracking, as well as

• The leaching process itself causes a loss of matrix elements.

The partitioning of pollutants between a solid and liquid phase (e.g., assuming local equilibrium) is combined with the mass transport of aqueous or dissolved elements in the leaching process. The sum of diffusion, impeded diffusion, tortuosity effects, and effective surface area effects through the material’s pore structure to the environment is known as mass transport. Solution pH, redox, the presence of dissolved organic matter, and biological activity are all important chemical parameters that influence a constituent’s liquid-solid partitioning (LSP).

Physical properties including relative hydraulic conductivity, porosity, and fill geometry all play a role in influencing how quickly constituents move through a solid and into a passing liquid phase.

The process is universal in nature, since any substance exposed to water may leach components from its surface or interior, depending on the porosity of the material

Process of Leaching

The solvent comes into touch with the solid matrix for the first time. A solvent is a liquid that dissolves a material or solute. A solvent dissolves a solute, which is an element. As a result, the solvent will turn into a liquid, while the solute will be the component extracted from the solid matrix. Furthermore, in our tea example, the solute would be the extracted green tea, and the solvent would be hot water.

There are many different types of leaching processes, which are mainly categorized based on the reagents utilized, Such as Cyanide leaching (e.g. gold ore),Ammonia leaching (e.g. crushed ore),Alkali leaching (e.g. bauxite ore),Acid leaching (e.g. sulfide ore)

The reagents needed are determined by the ores or pretreated material being processed. Oxide or sulphide is a common feed for leaching.

A catalyst is a substance that changes or accelerates the pace of any chemical reaction without any change taking place by itself. A catalyst is usually used in smaller amounts compared with the reactants or reaction participants.

Lindlar is a heterogeneous catalyst composed of palladium formed on calcium carbonate and treated with different types of lead. A heterogeneous catalyst is a catalyst that is always in a different phase or situation (solid, liquid, or gas solution) with the reactant solution.

The term “Lindlar” was awarded after Herbert Lindlar, their founder. Using lead will be needed to deactivate the palladium at some locations. Because of the existence of lead, this is often denoted as a “poisoned catalyst.” A catalyst becomes poisonous when its potency begins to decline in the presence of another chemical substance known as poison catalyst.

To poison the palladium, different compound contaminants such as lead acetate and lead oxide are used. The palladium element is normally just 5 percent of the catalyst’s overall weight. The catalyst is applied to alkenes to hydrogenate alkynes.

Lindlar’s Catalyst

A substance that changes or accelerates the pace of any chemical reaction without any change taking place by itself is a Catalyst.

Lindlar is a heterogeneous catalyst composed of palladium that is formed on calcium carbonate and treated with different types of lead. A heterogeneous catalyst is a catalyst that is always in a different phase or situation (solid, liquid, or gas solution) with the reactant solution. Lindlar’s Catalyst is used for the hydrogenation of alkynes into alkenes. The Lindlar’s Catalyst is used, on a large scale, in the synthesis of Vitamin A, and also used in the synthesis of dihydro vitamin K1.

The term “Lindlar” is named after a British chemist, Herbert Lindlar, their founder. 

Properties of Lindlar’s Catalyst

Lindlar’s catalyst has a specific surface area of 150-260 m²/g and consists of Impurity less than 0.5%

The water content of Lindlar’s catalyst is less than 5%, and the pH is 8.

Lindlar Catalyst Preparation

Lindlar Catalyst is prepared by lowering the palladium chloride in a calcium carbonate mixture and lead acetate is added to it. A catalyst with a large surface area is obtained and this increases the reactivity. If the catalyst is used to reduce alkynes to alkenes, the introduction of quinoline prevents further reduction to alkanes. Quinoline here serves as a deactivator to improve the catalyst’s selectivity.

Lindlar catalysts, which are available for commercial purchase, are also prepared in laboratories with the reduction of palladium(II) chloride in semi-liquid calcium carbonate and the subsequent poisoning of the resulting mixture with a suitable catalyst poison. Common choices here are lead acetate, lead(II) oxide, and quinoline.

It’s normally prepared by lowering palladium chloride in a calcium carbonate mixture accompanied by adding lead acetate. Finally, a catalyst with a large surface area is obtained which increases the reactivity. Provided that the catalyst is used to reduce alkynes to alkenes, the introduction of quinoline prevents further reduction to alkanes. Quinoline, therefore, serves as a deactivator to improve the catalyst’s selectivity.

Lindlar Catalyst Formula: Pd/CaCO₃

Lindlar Catalyst Structure

()

Lindlar Reaction Mechanism

Alkyne hydrogenation to alkenes involves the presence of molecular hydrogen (H₂) that lowers the alkyne to alkenes. The Hydrogen (H₂) atoms are introduced to the alkenes in pairs where the alkynes ‘ triple bond is reduced to a double-bonded alkene. 

()

In addition, the further reduction to one single bond is obstructed. In fact, the reduction of alkenes to alkanes is quicker than the reduction to alkenes due to the addition of quinoline.

In the above-mentioned hydrogenation reaction, the hydrogen atom is transferred to the same side (cis) of the alkyne, resulting in cis alkenes by introducing syn (addition of two substituents on the same side of a double or triple bond resulting in a decrease in bond number). All hydrogen and alkyne are closely bound up with the catalyst’s large surface where the hydrogen atoms then slowly bind into the alkyne’s triple bond.

Therefore, alkyne hydrogenation becomes stereoselective and occurs by syn addition. Stereoselectivity leads to the formation of an uneven mixture of stereoisomers (isomeric molecules that have the same molecular formula but different tridimensional atom orientations in space). In addition, the reaction is exothermic.

Lindlar’s Catalyst Examples

Using the Lindlar catalyst 1-phenylpropyne is reduced in this catalytic hydrogenation reaction. The alkyne is lowered to the equivalent cis alkene but not reduced to the alkane any further. If the catalyst had been Pd alone (without a poison), the alkene could not be extracted as it would be reduced easily to the equivalent alkane.

()

Herpes disease is caused by herpes virus and can be cured by the drugs containing lysine. Lysine is an essential amino acid for the human body. Lysine is not only used in the treatment of herpes but for various other diseases as well. It also has many culinary applications. In this article we will discuss chemical aspects of lysine, its structure, sources and uses. 

What is Lysine? 

Lysine is an essential -amino acid which is found in many foods as protein. Its symbol is Lys or K. As we know amino acids are the basic structural units of protein, so Lysine is used in the synthesis of proteins. As it is an [alpha] – amino acid so, it contains [alpha] – amine group and [alpha] – carboxylic acid group. We will discuss its structure in detail in the next section. 

It is essential for our body, but our body cannot synthesize it on its own. So, it must be obtained from foods. Lysine helps in animal growth as well. That’s why Lysine supplements are used as animal feed, specially for chickens and pigs for their optimal growth and production of meat. Some plants and bacteria can synthesize lysine from aspartic acid which is also an amino acid. It is synthesized in organisms by mainly following two biosynthetic pathways –

It was 1st isolated in 1889 by German Chemist Ferdinand Heinrich Edmund Drechsel from the casein phosphoprotein present in milk. Ferdinand Heinrich named lysine as ‘Lysin’. After almost thirteen years of its discovery and isolation, lysine was synthesized in 1902 by German Chemists Emil Fischer and Fritz Weigert. They determined the structure of the lysine as well. 

As lysine is vital for many biological processes so its deficiency can cause many diseases such as anaemia, defects in tissues, protein energy deficiency etc. It is a vital organic compound for growth of plants and animals as well. Thus, lysine is an important – amino acid for various processes occurring in human beings, animals and plants as well. 

Structure of Lysine 

Lysine contains [alpha] – amine group (In form of protonated -NH3+), [alpha] – carboxylic acid group (In form of deprotonated -COO–), and a lysyl side chain [(CH2)4NH2] in its carbon chain. It is a covalent organic compound. It is encoded by the genetic codes AAA and AAG. It has a chiral [alpha] – carbon. Its enantiomer L – Lysine in which [alpha] – carbon is in the S configuration and is biologically active.  

(Image to be added soon)

Amino Acid Structure 

[alpha] – Carbon, amino group and carboxylic acid group are the backbone of lysine. Its chemical formula is C6H14N2O2. It is a linear amino acid molecule. Lysine is a base and water soluble. It forms hydrogen bonds with other molecules. Its structure formula L-lysine is given below –

(Image to be added soon)

Structure of L- Lysine

General Structure of lysine –

(Image to be added soon)

Foods Rich in Lysine or Sources of Lysine 

Lysine is essential for proper growth and is used in biosynthesis of protein. As you know, lysine cannot be synthesized by our body and we must take it through diet. So, it becomes necessary for us to include lysine rich foods in our diet. As lysine is used in biosynthesis of proteins, so it naturally occurs in protein rich food items. 

Meat (red meat), eggs, rajma, chickpeas, few species of fishes, soybeans, tofu, fenugreek seeds, cheese, pork, chicken etc. are good sources of lysine. Other beans, dairy products and Brewer’s yeast, mushroom also contain lysine. 

Apart from these natural sources of lysine various other lysine supplements are also available. It is available in the form of tablets, capsules, creams and liquid solution form. 

Function of Lysine 

Lysine is necessary for the healthy functioning of the human body and some organisms, plants and animals. Catabolism of lysine takes place in the liver. Amino acids of lysine provide glucose to the human body through metabolism. It is metabolized into acetyl – CoA which forms adenosine triphosphate. Adenosine triphosphate is the currency of energy in our body. Lysine plays a vital role in the citric cycle in animals. 

Allysine is a derivative of lysine which is used to produce collagen and elastin. These are essential for skin, joints etc. 

Uses of Lysine 

Lysine plays an important role in many biological processes. Its most common role is proteinogenesis. It is a base of protein structure. It is considered as amphipathic which means it shows both hydrophilic and lipophilic properties. Because of this it becomes even more important for various processes. Its amino group forms hydrogen bonds, covalent bonds and salt bridges with other molecules. Therefore, lysine contributes to protein stability as well. Lysine plays a major role in epigenetic regulation. Many histone modifications involve lysine. These modifications can affect gene regulation. 

Lysine plays a key role in calcium homeostasis and fatty acid metabolism. It is involved in the crosslinking of helical polypeptides in collagen. It is a precursor for carnitine. Carnitine transports fatty acids to the mitochondria. 

Lysine is useful in treatment of herpes. Herpes is caused by herpes simplex virus. Arginine promotes the growth of herpes simplex virus and lysine blocks the activity of arginine. 

It helps the body to absorb calcium. As calcium is a must for healthy bones. So, researches show that lysine helps in prevention of osteoporosis. 

Sometimes athletes take lysine supplements as protein supplements as studies show that lysine helps muscles to recover faster after stress. 

Lysine is used as animal feed as it helps in their optimal growth. Thus, lysine is a key ingredient of food, which is used in poultry farms, pig farming etc. to feed chickens, pigs and other animals for their optimal growth and high – quality meat. 

Early studies show that lysine is effective in treatment of canker sores and diabetes. Studies state that it can even prevent canker sores and diabetes. It reduces the blood sugar level. Lysine is helpful in reducing the stress as well. 

A derivative of lysine is used in pain management as it serves as an anti – inflammatory agent. It can be helpful in preventing cardiovascular diseases and blood pressure fluctuations. 

Deficiency of Lysine 

As lysine plays key roles in many biological processes and essential for our body, so its deficiency causes various diseases also. Most of the diseases due to lysine are the result of downstream processing of lysine. Lack of lysine causes disease related to connective tissues. Lack of lysine may cause lack of carnitine levels in the body which may cause many health – related issues as carnitine transfers fatty acids to mitochondria and mitochondria is known as powerhouse of the cells. Deficiency of lysine may cause anaemia, protein energy malnutrition, neurological disabilities, epilepsy, ataxia and psychomotor impairment.  

This ends our coverage on the topic “Lysine”. 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.

The formula MnO2 is commonly known as Manganese Dioxide. It is a solid that has a black-brownish colour. Manganese dioxide, when found in nature, is known as pyrolusite. It is considered to be the most plentiful out of all the manganese compounds. Pyrolusite is the principal ore of the compound manganese dioxide. Manganese Dioxide is commonly used for batteries and also as pigment for other Manganese compounds. An impure form of manganese can be obtained by reducing manganese dioxide with carbon. Manganese Dioxide is the inky quadra positive manganese compound. 

MnO2 compound name is given as dioxo manganese. It is a certain MnO2 chemical name. 

Where is Manganese Dioxide Found?

The most common Manganese bearing minerals are Pyrolusite and Rhodochrosite. These are the basic sources of manganese dioxide in nature. Moreover, manganese dioxide and the other manganese compounds are found on the ocean floors too. The countries which supply the maximum Manganese are Brazil, USSR, Russia, India, Africa, Australia and New Zealand. The primary way in which manganese is produced is by the reaction of the oxides with sodium, aluminium and magnesium. Chemically in the laboratories, it is produced by electrolysis. Manganese is present in four different forms. One form is stable in room temperature and is known as alpha form. 

Chemical Properties of Manganese Dioxide 

Chemical Formula: MnO2

Molar Mass: 86.9368 g/mol

Appearance: Brown – black solid

Density: 5.026 g/cm3

Manganese Dioxide Melting Point: 535 °C

Covalently Bonded Unit: 1

Solubility in Water: Insoluble 

Physical Properties of Manganese Dioxide

Odour: Odourless 

Appearance: Brown – Blackish solid

Complexity: 18.3 

MnO2 Oxidation Number: +4

Solubility: Insoluble in water 

Hydrogen Bond Acceptor: 2

Properties of Manganese Dioxide

• Magnesium dioxide is abundantly used in the ceramic industry. All the raw materials used in the making of glass contain some amount of iron. This iron is usually in the form of ferric oxides. The use of manganese dioxide in such industries is highly beneficial and practical. 

• Manganese ores are again commonly used in dry cell batteries. Many of these cells need to be activated by physical or chemical means. These means are manufacturing techniques that need special machinery and work at certain temperatures only. 

• Glass often gets a tint due to the presence of impurities. Manganese dioxide gets rid of the green tint produced as a result of the various iron impurities. 

• The positive electrode carbon in batteries is secure indeed by a layer of magnesium dioxide. Carbon is also present around It. 

• A majority of manganese dioxide is used in the steel industry. Manganese is basically used in the deoxidation of steel. 

• The black-brown pigments present in paint are basically manganese dioxide. 

• Soft drink cans also have a specific alloy present in them. This alloy is made from manganese dioxide. 

Solved Examples: 

Manganese Dioxide as a Catalyst:

Oxygen is produced in the laboratory in the presence of hydrogen peroxide and manganese dioxide. Manganese dioxide here acts as a catalyst and accelerates the reaction. 

2H2O2(aq) → 2H2O(l) + O2(g)

Here manganese dioxide is the accelerant. When manganese dioxide is added to hydrogen peroxide, bubbles of oxygen are produced. 

3MnO2 (s) + 4Al (s) → 3Mn (I) + 2Al2O3 (s)

Manganese Dioxide Reacting With Potassium Chlorate

Potassium chlorate (KClO3) is heated in the presence of manganese dioxide catalyst and it decomposes to form potassium chloride and oxygen gas. 

The balanced chemical equation is: 

2KClO3 → 2KCl + 3O2

The above is the laboratory process of oxygen generation. The chemically produced oxygen is suitable for usage immediately. It has to go through a few more filtration processes. 

Manganese Dioxide Reacting With Aluminium

Manganese dioxide , when reacted with aluminum, gives metallic manganese and aluminum oxide. Along with this, a lot of heat is generated. It is an exothermic reaction as the change in enthalpy comes out to be negative. 

MnO2 + Al → Al2O3 + Mn 

Fun Facts About Manganese and Manganese Dioxide

• Manganese was first discovered in the year 1774. 

• Historically it has been seen that cave paintings in the Stone Age contained manganese pigments. 

• Manganese has a very prevalent look to that of iron. In contrast to Iron it has a silver – grey colour. 

• It Is well known that iron rusts the most, but Manganese rusts as much as iron only. In fact research has shown that at times, manganese rusts more than iron too sometimes. 

• Manganese dioxide is present abundantly In nature. 

• The most common uses of manganese dioxide are production of stainless steel, glass industry, paint industry and more. 

• Manganese is found in the mitochondria for functioning of living cells. Mitochondria, also known as the powerhouse of the cell, depends on manganese for proper functioning of the human cell body. 

• Most of the manganese Is present in the skeleton of the human body. 

• Although manganese is not toxic in a light amount, a handful of manganese usage can prove to be lethal.