Category: Chemistry Notes PPT

Hassium is a chemical element with the atomic number 108 and symbol Hs. It belongs to group 8 and period 7 of the periodic table of elements. It is a transition metal which is solid at room temperature. This element is one of the densest elements due to the presence of 108 protons in its nucleus. The atomic weight of an atom of the Hs element is 269. The electronic configuration of this radioactive metal is [Rn] 5f146d67s2. Most of the isotopes of Hs are unstable and have very short lives. The basic information of this radioactive element is as follows. 

Basic Information of Radioactive Element

The above image shows the position of Hassium in the periodic table. 

Discovery and Naming

Chemists from different regions tried to make several attempts to synthesise Hassium before its official discovery. In 1984, the German scientists including Peter Armbruster, Gottfried Munzenber and co-workers claimed to produce this element at GSI. At the same time, the Russian scientists also claimed to synthesise this element. In 1993, the report formed by the International Union of Pure and Applied Chemistry and IUPAP assigned the major credit to a German scientist. According to them, the report made at GSI was more conclusive as compared to the Russian scientists. 

Before the official discovery of Hassium, chemists referred to it as element 108 or eka-osmium. The IUPAC and IUPAP gave the official credit to German scientists due to their detailed work. Peter Armbruster and co-workers proposed the name Hassium for this element. The name Hassium comes from the Latin word Hess of Hess, where the scientists produced this element for the first time. In 1997, the IUPAC finally named the element 108 as Hassium. 

Occurrence

Hassium has not been observed in nature until now. The reason behind it is that the half-lives of all known isotopes of this element are too short. Hence, no primordial hassium could have survived to present from the beginning of this universe. However, there can be some isotopes of this element which may have longer half-lives. It means that they might be present on earth in trace quantities. Hassium was first synthesised by cold fusion of lead-208 with iron-58 nuclei by the following reaction. 

208Bi + 58Fe → 265Hs + 1n

Hs element decays very quickly. Hence, scientists had minimal quantities of Hs until now. A Russian scientist Victor Cherdyntsev also claimed to discover Hassium occurring naturally. However, he couldn’t verify his statement.  

Properties of Hassium

Due to the limited and expensive production of Hs, many properties of this element remain unknown. Only some predictions are available according to the various calculations made by chemists. Scientists believe that this radioactive element is a dense solid metal at room temperature. It must have a shiny and metallic appearance. Various calculations made by chemists suggest that it can be the heaviest element in group 8. The predicted density of this transition metal is 41g/cm3 at standard temperature and pressure. 

Hs must crystallise in hexagonal close-pack structure as per the predictions. The expected atomic radius of this metal is around 126pm. The predicted electronic configuration of Hs+ ion is [Rn] 5f14 6d57s2 due to relativistic de-stabilisation of the 6d orbital and stabilisation of the 7s orbital. Instead of a 7s electron, the Hs+ ion gives up 6d electron which is opposite in its lighter homologues. 

Hs is present in the 6d series of transition metals as the sixth metal. Hence, scientists predicted that it must have similar properties like the platinum group metals. The expected oxidation states of Hassium according to its electronic configuration are +8, +6, +4, +3, and +2. Hs is also likely to react with oxygen to give volatile tetraoxide. 

Isotopes

Hassium has no naturally occurring or stable isotopes. Currently, scientists had synthesised twelve isotopes of Hs, and all of them are radioactive. The mass number of these isotopes of Hs element ranges from 263 to 277. All known isotopes of Hs except Hassium-277 decay predominantly through alpha decay. Hassium-277 is the only known isotope of Hs which undergoes spontaneous fission. The half-lives of all the isotopes of Hs are too short, even less than 22 seconds. The most stable isotope of Hs is 269Hs which has a half-life of around 16 seconds. 

Scientists have a particular interest in isotope 270Hs due to its magic number of nuclear stability. In 1991, Zygmunt Patyk and Adam Sobiczewski predicted some interesting things. According to them, the neutron magic number for deformed nuclei (non-spherical nuclei) is 162, and the proton magic number for it is 108. Hence, the nucleus of this isotope of Hs has doubly magic which leads to low decay energy.

In order to understand the reactions and mechanisms of homogeneous as well as heterogeneous reactions, it is important to develop a basic understanding of the terms homogeneous and heterogeneous and how they are different from each other. 

A heterogeneous reaction is a class of reaction that happens between two or more reactants that are present in two or more different phases, for instance, the phases of the reactants can be solid-liquid, solid-gas or two immiscible liquids. There are certain reactions that take place on the surface of another substance. To be more specific, when two reactants undergo a chemical change on the interface of a catalyst that can be in solid or liquid form (studies suggest mostly solid) also falls under the category of heterogeneous reactions. 

Heterogeneous reactions can be defined as that class of reactions which occurs between two or more reactants which are present in two or more different phases. For example, the phases of the reactants can be either liquid and solid, gaseous or solid or two liquids which cannot be mixed. There are many reactions which take place on the surface of other substances which means that when two reactants undergo a chemical change then the interface of the catalyst is either solid or liquid forms. All of these also come under heterogeneous reactions. 

Some Examples of Heterogeneous Reactions are

The reaction of solid metals with acids, the corrosion of iron, the electrochemical reaction occurring in batteries and electrolytic cells are all subjected to a heterogeneous reaction. Most of the research and studies regarding heterogeneous reactions are done for heterogeneous catalysts such as the reaction between liquids or gases that happens on the surface of a solid catalyst that helps in initiating the reaction or increasing the reaction rate. 

The most important reactions are between gases and reactions happen between liquids or substances which are dissolved in these liquids. Examples of such reactions are the reaction between oxygen and natural gas which leads to the production of flame or the reaction of solutions of acid and bases in aqueous solutions. 

On the other hand, a homogeneous reaction is a class of reactions where the reactants are present in a single phase, that is, either solid, liquid, or gas. Homogeneous, unlike heterogeneous reaction, is based on the physical state of the reactants. The important homogeneous reactions are the reactions between gases and reactions happening between liquids or substances dissolved in liquids. 

Examples of homogeneous reactions are the combination of natural gas and oxygen to produce flame or a reaction of aqueous solutions of acid and bases. Out of the two homogeneous and heterogeneous reactions, the former is easy to understand as the nature of homogeneous reactions solely depends upon the nature of the interaction of the reactants.     

Heterogeneous Chemical Reaction

The chemical interactions that happen between the two reactants that belong to different phases are illustrated with various heterogeneous chemical reactions of reactants of different phases for a clearer understanding of the nature of heterogeneous reactions.

1. Solid-Fluid (Liquid and Gas)

1. Dissolution of solids, example, MgCO3(S) + 2 HNO3(L) → Mg(NO3)2(aq) + H2O(L) + CO2(g)

2. Chemical vapour deposition , example, SiH4(g) → Si(S) + 2H2

3. Sublimation, example, U(s) + 3F2(g) → UF6(g)

4. Reduction of solid oxides, example, NiO2(s) + H2(g) → Ni(s) + H2O(g)  

5. Metal reduction, example, Zn(s) + O2(g) → ZnO2(S)

2. Liquid – Gas

Dissolution with chemical reaction, examples,

1. Cl2(S) + 2NaOH(l) → NaOCl(l) + NaCl(l) + H2O(l)

2. 3NO2(g) + H2O(l) → 2HNO3(l) + NO(g)

3. Solid – Solid

Heterogeneous precipitation and calcination reaction, for example,

CoO(S) + Al2O3(S) → CoAl2O4(S)

All the heterogeneous reactions have one thing in common and that is before any heterogeneous chemical reaction occurs the reactant in a bulk of a particular phase is transferred to either the interface of the two bulk phases or is completely transported to the bulk of another phase. Usually, heterogeneous reactions take place in a number of steps among which one or more chemical steps involved are accompanied by the intermediate steps that are purely physical in nature and are just responsible for transporting the bulk phase of certain reactants to the bulk phase of other reactants. The concentration of the reactant in one bulk phase is different from the concentration of reactants at the interface of the two different bulk phases and this difference in the concentration is actually the driving force for this phase transfer process. Thus in order to study the rate of chemical reaction, these are the factors that are of utmost importance. 

1. The change in the rate equation is mostly from the mass transfer from one phase to the other.

2. The contact pattern of the reacting phase.

Thus in steady-state condition when the heterogeneous reaction takes place in multiple steps, then the overall rate of reaction is equal to the rate of reaction of the individual reactions taking place in a series. Hene the rates of reaction can be expressed as roverall = r1= r2 =………= rn.

Thus when the mass transfer takes place the rate of reaction is calculated on the basis of molar reflux which is basically no. of moles per unit time per surface. Therefore, reaction rate based on unit volume will be

-rA = (-1 / V) (dNA / dt) = mole of a reactant / (volume of fluid * time )

Based on the mass of a solid,

-rA। = (-1 / W) (dNA / dt) = mole of a reactant / (mass of * time )

Based on unit interfacial surface/unit surface of solid

-rAII = (-1 / S) (dNA / dt) = mole of a reactant / (interfacial surface * time )

All these rates of reactions are based on

mole of a reactant / time  = (-rA * V) (-rA। * W) (-rAII * S)

-rA = (W /V) rA।

-rA। = (S / W) rAII 

-rAII = (V / S) rA

Thus for a non-elementary rate of reaction as follows

C6H5CH3(l) + H2(g) → C6H6(l) + CH4(g)

The rate of reaction for this heterogeneous reaction will be

-r⋎। = (kPH2 PT) / (1 + KBPB +  KTPT)

where  KB and KT are the absorption constants with units kPa-1 (atm-1) and the units of reaction rate is

kk = mol toluene (C6H5CH3) / kg_cat • s •  kPa2

Alternatively, the rate of reaction in terms of concentration can be written as

Pi = Ci RT.

Homogeneous Reactions

A homogeneous reaction can be defined as the reaction where all the reactants and the products formed from the chemical interaction of the reactants are all in one single phase that can be gas, liquid or solid phase and do not possess any phase boundaries. A more clear picture of the nature of the reaction can be drawn by a few examples of homogeneous reactions. 

2SO2(g) + O2(g) ⇋ 2SO3(g) whose rate of forward reaction is v1 = k1 • [SO2]2 • [O2] and the rate of backward reaction will be v2 = k2 • [SO3]2 . Now when a homogeneous reaction proceeds, just like a heterogeneous reaction, it takes place in a series of many intermediate chemical reactions and it constitutes the mechanism of the reaction and is known as a non-elementary reaction. This particular series mechanism of non-elementary homogeneous reactions rate law. Thus elaborating the derivation of the rate law with an elementary example of homogeneous reaction as follows:- 

2H2 + O2 → 2H2O

This reaction actually follows many elementary steps:

H2 + O2 → HO2 + H

H2 + HO2 → OH + H2O

OH + H2 →  HO2 + H

O2 + H → OH + O

H2 + O → OH + H

Now, for most of the reactions, the elementary steps that are the constituents of the mechanism of such reactions are not known and only single reactions are observed. It is because the amount of reactants and the products that are formed in the intermediate reactions formed are very few and often escape detection. Also, the velocity with which they form and dissociate is very fast. Thus it makes it very difficult to detect. Thus based on the experimental observations of the collision theory, the law of mass action states that, for an elementary reaction, its reaction rate at a constant temperature is equal to the product of the concentration of the reactants. Thus for a single elementary reaction, the reaction rate is given by:-

( AA BB CC T t) = k AA BB, where k is the rate constant. Thus the series of equations that describes the evaluation of each species is given by-

dAA / dt = -k a AA BB

dBB / dt = -k b AA BB

dCC / dt = -k c AA BB

And this equation is said to be in order 2 and is also very difficult to determine due to the complexity of the mechanism of such a reaction. Thus, it has also been observed that the rate of reaction is approximated to be proportional to the power of the products of concentration of the reactants, the equation is as follows,

( AA BB CC T t) = k AAα BB𝛽

Where α is called the order of reaction of A, 𝛽 is called the order of reaction of B and the sum of the two exponents, n =  α + 𝛽 is called the rate of reaction. Also, the rate constant k of the nth order of reaction has dimension (time)-1 (concentration)n-1. Thus the rate of reaction between hydrogen and bromine will be

H2 + Br2 → 2HBr

( [H2] [Br2] HBrHBr) = k1 [H2] [Br2]½ / k2 + HBrHBr / [Br2]

Heterogeneous Catalytic Reaction

Heterogeneous catalytic reactions are the reactions that occur in the presence of a catalyst where the phase of the catalyst differs from that of the reactants. Catalysts are generally useful for a reaction to increasing the rate of reaction without themselves getting consumed and thus can be used later. In heterogeneous catalytic reactions, the catalysts are generally present in the solid phase and the reactants are generally in the gaseous phase. These reactions occur on the interface of the catalyst where the molecules of the reactants are adsorbed on the surface and then the reaction occurs resulting in the formation of desired products which are then desorbed from the surface of the catalyst. Thus the thermodynamics, heat transfer or mass transfer generally affects the rate of heterogeneous catalytic reaction. One of the most common examples of heterogeneous catalyst reaction is hydrogenation of ethane on the catalytic solid surface that involves adsorption, reaction and desorption. This is illustrated by the diagram below. 

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This kind of reaction is commonly known as heterogeneous catalytic hydrogenation and is one of the most widely used methods in industries these days to produce chemicals. Heterogeneous catalytic hydrogenation reactions have found their place mostly in industries like pharmaceuticals, flavour and fragrance industries, fine chemicals, agrochemicals and dietary supplements. Most of the chemicals that are produced in these industries are using 10-20% of heterogeneous catalytic hydrogenation reactions for their production. It is because the catalytic reactions are generally highly selective in nature and are therefore easy to work upon. The reactions are atomic efficient and the catalyst does not get consumed and can be recovered and recycled.  

In industrial heterogeneous catalytic hydrogenation reactions, the most precious metal catalysts are deposited from the solution in form of a powdery substance carefully on a support that is heavy, porous, bulky, cheap and usually granular like active carbon or calcium carbonate or alumina. For example, platinum on carbon is produced by the reduction of chloroplatinic acid that is catalysed by 5% ruthenium on activated carbon or 1% platinum on alumina. One of the most essential steps in the catalytic reaction of any kind is adsorption. Now adsorption is classified broadly into two parts, namely, physisorption and chemisorption. Physisorption is weak adsorption bonding and the molecules of the reactants are bound to the surface of the catalyst by weak Van Der Waal forces like dipole-dipole moment, induced dipole interactions and London dispersion forces. whereas chemisorption is a strong adsorption bonding where the molecules of the reactant approach closely to the atoms on the surface of the catalyst through electron cloud overlapping. Thus in this adsorption process, the adsorbent and the adsorbent share a chemical bonding by sharing their electrons. Usually, the heterogeneous catalytic reaction falls between these two processes. Thus the mechanism of the catalytic reaction in a heterogeneous system will be in the following steps:

1. Diffusion of reactants to the surface and the rate of diffusion of the reactants on the surface is directly proportional to the concentration of the reactants and the thickness of the boundary layer.

2. Adsorption of reactants on the surface of the catalyst happens when the adsorbate forms bonding with the adsorbent. Thus the ability of the atoms or the molecules to form bonds with the atoms on the surface of the catalyst can be efficiently calculated as a sticking coefficient. This represents the percentage of the ratio of the no. of molecules or atoms that have stuck to the surface of the catalyst.

3. The reaction is indicated by the bonds that are formed by the atoms of reactants and the catalyst.

4. Desorption of the products. This happens when the bonds between the product that is formed and the catalyst breaks.

5. The product formed is diffused from the surface of the catalyst. This happens when the bond is cleaved and the product diffuses from the surface of the catalyst without changing the characteristics of the catalyst.

An example of this is the contact process which is used in the industries to produce sulphuric acid in high concentrations. Earlier platinum was used as a catalyst but since it has a tendency to react with the arsenic impurities that are present in the sulfur feedstock, thus vanadium oxide (V2O5) is now used as the active catalyst. In this process sulfur oxide and oxygen are gases and vanadium oxide is solid.

2SO2(g) + O2(g) ⇋ 2SO3(g) in presence of V2O5(S)

2V2O5(S) + 2SO2(g) ⇋ 2SO3(g) +2V2O4(S)

2V2O4(S) + O2(g) ⇋ 2V2O5(S)

2SO2(g) + O2(g) ⇋ 2SO3(g)

Diatomic molecules are the ones, which are composed of only two atoms, either of the same or different chemical elements. The prefix ‘di-‘ is the Greek origin, which means “two”. If a diatomic molecule contains two atoms of similar elements, such as oxygen (O2) or hydrogen (H2), it is referred to as homonuclear. On the other side, if a diatomic molecule contains two different atoms, such as a nitric oxide (NO) or carbon monoxide (CO), it is referred to as heteronuclear. The bond present in a homonuclear diatomic molecule is non-polar.

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Occurrence

Mostly, hundreds of diatomic molecules have been identified in the environment of the Earth, in the interstellar space, and in the laboratory. Around 99% of the atmosphere of the Earth is composed of two species of diatomic molecules, which are nitrogen (78%) and oxygen (21%). The natural abundance of hydrogen (H2) present in the atmosphere of the Earth is only of the order of parts per million, whereas H2 is the most abundant diatomic molecule present in the universe. Indeed, the interstellar medium is dominated by hydrogen atoms.

A Few Common Diatomic Molecules

Hydrogen Molecule (H2): Dihydrogen molecule belongs to the diatomic molecule’s family, which contains two hydrogen atoms bonded to each other with a covalent bond. As per the atomic number of hydrogen, it has only 1 electron in its 1s orbital. The electronic configuration of the H2 molecule can be given as follows.

H2: (σ1s)2

Bond order = = = 1

Because of the absence of unpaired electrons present in the hydrogen molecule, it is described as diamagnetic in nature.

Lithium Molecule (Li2): The lithium molecule belongs to the diatomic molecule’s family, which contains two lithium atoms that are bonded to each other with a covalent bond. The electronic configuration of the Li2 molecule can be given as follow.

Li2: (σ1s)2 (σ*1s)2 (σ2s)2

Bond order == 1

Therefore, the Li2 molecule is stable and diamagnetic because of the absence of unpaired electrons.

Carbon Molecule (C2): This molecule belongs to the diatomic molecule’s family, which consists of two carbon atoms that are bonded to each other with a covalent bond. The electronic configuration of the Carbon molecule can be given as follows.

C2 :(σ1s)2 (σ*1s)2(σ2s)2 (σ *2s)2 (π2p2x= π 2p2y)

Bond order = = 2

Because of the absence of unpaired electrons, the C2 is diamagnetic in nature. Moreover, because of the presence of 4 electrons in the pi bonding orbitals, the double bond in C2 (bonding in homonuclear diatomic molecules) contains both pi bonds.

An Oxygen Molecule (O2): The oxygen molecule belongs to the diatomic molecule’s family, which contains two oxygen atoms, which are bonded to each other with a covalent bond. The electronic configuration of the Oxygen molecule can be given as follows.

O2: (σ1s)2 (σ*1s)2 (σ2s)2 (σ *2s)2 (σ2pz)2 (π2p2x= π 2p2y) (π*2p1x= π*2p1y)

Bond order = = 2.

Because of the presence of 1 unpaired electron, the O2 molecule should be paramagnetic.

Helium Molecule (He2): As per helium atomic number, it contains 2 electrons in 1s orbital. The electronic configuration of this molecule as per the molecular orbital theory can be given as follows.

He2: (σ1s)2 (σ*1s)2

Bond order == 0.

Therefore, the He2 molecule is unstable and does not exist.

Diatomic Gas

A gas, having two atoms in its molecule (For example, H2 – Hydrogen molecule holds 2 H-atoms bound together using an electrostatic force field.

The electrons of 2 atoms overlap on each other, and this potential of overlapping plays a major role in its binding.

Gases are made up of only two atoms that can be either similar or various.

Oxygen, Hydrogen, Bromine, Nitrogen, Chlorine, Fluorine, and Iodine are the 7 common gases that exist as the diatomic molecules of a similar element. However, still, there are examples of diatomic molecules made up of non-identical atoms like hydrogen chloride, carbon monoxide, and nitric oxide.

About Gase’s Diatomicity and Reason

We have many of the gaseous elements such as Oxygen, Hydrogen, Nitrogen, Fluorine, Chlorine, and more among the compounds Nitric oxide, Carbon monoxide, Hydrogen Fluoride, Chlorine monofluoride, Hydrogen Chloride, and so on.

Because it all comes down to the valency or the availability of electrons, forming chemical bonds. H contains only one bond and is monovalent. Thus the hydrogen molecule has only 1 bond.

Since oxygen can be given as O2, which we breathe, and O3 as Ozone. Ozone is not stable compared to dioxygen, and the equilibrium of the process given below lies to the right.

2O3⇌3O2

The molecule’s stability is also a factor for O4, N3, N4, and so on are theoretically possible but are energetically unfavorable because of their diatomic counterparts. Whether such a type of molecule is feasible or not can be determined rigorously by the application of Molecular Orbital theory.

Did You Know?

• An ideal gas can simply be described as a theoretical gas composed of many randomly-moving and non-interacting particles, which do not exist in nature. However, the real gases can behave the same as ideal gases under some specific conditions when the intermolecular forces become negligible.

Formula: HCl

Molar mass: 36.46 g/mol

Appearance: Colourless, transparent liquid

It is a simple diatomic molecule consisting of a hydrogen atom and a chlorine atom connected with a covalent single bond. Since the chlorine atom is much more electronegative than the hydrogen atom, the covalent bond between the atoms is polar.

What is Hydrochloric Acid?

• Hydrochloric Acid is a strong corrosive Acid

• A solution of hydrogen chloride in water is known as Hydrochloric Acid. Its Chemical formula is HCl

• It has a unique pungent smell

• One of its common application is that it is commonly used a laboratory reagent

• It is used both in its aqueous and gaseous form

Occurrence

It is a major component of the gastric juice also referred to as the gastric Acid.

Preparation of Hydrochloric Acid

Hydrochloric Acid is prepared by dissolving hydrogen chloride and water. When hydrogen chloride gas enters the water, the water molecules take the hydrogen atom in HCl(g) and pull it away from the chlorine atom. This is the dissolution process, which makes Hydrochloric Acid. 

[HCl + H_{2}O rightarrow H_{3}O + Cl^{-}]

Hydrogen chloride is also generated as by-products from industrial-scale production of other Chemicals. Industrially it is prepared by the combustion of hydrogen in chlorine. Due to evaporation, the high concentration of HCl is hard to prepare. 

Uses of Hydrochloric Acid

• Hydrochloric Acid is a strong Acid as it is completely dissociated in water.

• It can be used to prepare salts containing Cl- ions called chlorides.

• It is also used in titration for determining the number of bases as it is a strong Acid and will give more precise results.

• Hydrochloric Acid is also used to prepare samples in Chemical analysis.

• Concentrated Hydrochloric Acid can dissolve a variety of metals to form hydrogen gas and oxidized metal chlorides.

What Makes HCl an Excellent Acidifying Agent?

It is a pure reagent and least hazardous to handle. It consists of non-corrosive and non- reactive chloride ions.

Physical Properties of Hydrochloric of Acid

The physical properties like boiling and melting points, density, and pH, of Hydrochloric Acid, varies depending on the concentration of Hydrochloric Acid in water. It is colorless with a highly pungent odor.

Chemical Properties of HCl

• HCl is a strong Acid.

• It is monoprotic therefore it can only release one proton (H+). In water; it completely dissociates to form hydrogen and chloride ions. The reason Hydrochloric Acid dissociates into hydrogen and chloride ions is because it is a polar covalent compound and therefore when added to water it ionizes.

• Concentrated Hydrochloric Acid can dissolve metals and form oxidized metal chlorides and hydrogen gas

• HCl is very corrosive; it attacks many metals like mercury, gold, platinum, tantalum, silver, and certain alloys are an exception.

• Non-corrosive in presence of glass.

Applications

Hydrochloric Acid is a strong inorganic Acid that is used in a variety of industrial processes.

1) Pickling of Steel

[ Fe_{2}O_{3} + Fe + 6 HCl rightarrow 3 FeCl_{2} + 3 H_{2}O]

This is a process in which dilute Hydrochloric Acid is used to remove rust or iron oxide from iron or steel before processing it for further wire production, a coating of sheet and strip, and tin mill products. This is required for all steel products that need further processing.

2) Cleaning Agent

Hydrochloric Acid can be used to clean any material that can withstand its effects as it is extremely powerful. It is also used to neutralize swimming pools if the pH level is high. This is done by pouring it into the pool while the pool pump is on.

3) To Regulate pH

Hydrochloric Acid is also used to regulate the Acidity pH of solutions. It is used to regulate the pH in a variety of manufacturing and treatment processes such as pharmaceuticals, swimming pools, drinking water, beverages, and food.

4) Production of Inorganic Compounds

Many inorganic compounds can be produced from simple Acid-based reactions resulting in inorganic compounds.

Some of them are listed below:

[ Fe_{2}O_{3} + 6 HCl → 2 FeCl_{3} + 3H_{2}O]

• Both PAC and iron (III) chloride are used as coagulation and flocculation agents in drinking water production, wastewater treatment, and paper production.

• Zinc chloride for galvanizing industry and battery production

• Calcium chloride and nickel (II) chloride for electroplating

[ CaCO_{3} + 2 HCl rightarrow CaCl + CO_{2} + H_{2} O ]

5) Production of Organic Compounds

Hydrochloric Acid is used in the production of organic compounds like vinyl chloride and dichloromethane which are used to produce PVC (polyvinyl chloride). Other than this Hydrochloric Acid is used to produce a variety of organic compounds like ascorbic Acid and pharmaceutical products.

6) Gastric Acid

Hydrochloric Acid is an important part of gastric juice produced in the body which helps in digestion. In the stomach, inactive pepsinogen is converted into active pepsin by HCl which then helps digestion by breaking the bonds linking amino Acids, a process known as proteolysis.

Hazards of Hydrochloric Acid?

If a small amount of Hydrochloric Acid is inhaled, it results in eye, nose, respiratory tract irritation and inflammation in humans, oral exposure can result in damage to the mucous membranes, stomach, esophagus etc. However continuous exposure to Hydrochloric Acid can result in gastritis, chronic bronchitis etc

Difference Between Hydrogen Chloride and Hydrochloric Acid?

Both hydrogen chloride and Hydrochloric Acid have the same formula. The difference is in the physical states they exist in. Hydrogen chloride is in a gaseous state while Hydrochloric Acid is in an aqueous solution.

So, this is all about Hydrochloric Acid. Applications of Hydrochloric Acid are one of the most important aspects of this section.

There are different methods of categorizing the Acids and Bases. Arrhenius Acid-Base and Lewis Acid base are the common methods used.

Arrhenius Acid-Base

Arrhenius Acid is such a substance that when mixed with water will dissociate and yield electrically charged atoms which increase the concentration of Hydrogen (H+) ions in the water. The H+ can’t exist alone in water as such but exist in the form of hydronium (H3O+) ions. Since it results in the increase in concentration of H+ ion, Arrhenius Acids are also known as proton donors or hydrogen ion donors.

On the other hand, Arrhenius bases are those  substances which when dissociated with water yield increase in the concentration of Hydroxide (OH–) ions. Further these are strong Acid, strong base or weak Acid and weak base. This classification is dependent on the number of respective H+ and OH– ions produced upon dissociation in water. 

Is Hydrochloric Acid(HCl) an Arrhenius Acid?

Hydrochloric Acid(HCl) is an arrhenius Acid, this can be confirmed from the Chemical equation given below which shows the reaction of Hydrochloric Acid(HCl) with water.

[ HCL +H_{2}O rightarrow  H_{3}O^{+} +CL^{-}]

Upon reaction with water, there is a yield of H3O+  AND Cl– ion. This means we get a hydronium ion in this reaction. The hydronium ion is further dissociated and the release of H+ ion can be seen as in the reaction shown below.

[ H_{3}O^{+} rightarrow H_{2}O + H^{+}]

Thus upon dissociation the Hydronium ion will result in release of a water molecule (H2O)  and a hydrogen (H+)  ion which will increase the concentration of H+ ions in the water. Hence,Hydrochloric Acid(HCl) is an Arrhenius Acid as it follows the definition of an Arrhenius Acid.

Hydrochloric Acid(HCl) as Lewis Acid

This is another way of defining Acids and bases, here the donation of an electron pair is the defining matter. The substance that is capable of accepting an electron pair is known as Lewis Acid and the substance capable of donating an electron pair is defined as an Lewis Base.

Is Hydrochloric Acid(HCl) as Lewis Acid?

Hydrochloric Acid(HCl) is capable of accepting an electron pair. The H+ ion in the H-Cl has a valence orbital where an electron pair can reside. The electron pair can be accepted from any lewis base that is capable of donating an electron pair. For example water.

In the reaction between water (H2O) and Hydrochloric Acid(HCL), the Oxygen (O) in water has a free electron pair which can be donated, and Hydrogen (H) in Hydrochloric Acid is capable of accepting that electron pair. When they react, the oxygen atom of water donates its free electron pair to the hydrogen atom of Hydrochloric Acid. Thus Hydrochloric Acid acts as a lewis Acid.

What is the Strength of Hydrochloric Acid(HCl)?

The estimate of the strength of an Acid is defined by the ease with which the Acid is able to release its proton i.e the hydrogen ion (H+) to the base it is reacting with or the ease with which the Acid releases its proton i.e the hydrogen ion (H+) upon disassociation . The relative strength of Hydrochloric Acid (HCl) with respect to other common Acids used is shown as below

Perchloric Acid (HClO4)>  Hydrochloric Acid (HCl) > Sulfuric Acid (H2SO4) >Nitric Acid (HNO3)

In this comparison we can evaluate that  Hydrochloric Acid (HCl) is a slightly weaker Acid than Perchloric Acid but is a very strong Acid as compared to Sulfuric Acid and Nitric Acid.

What is the Structure of Hydrochloric Acid(HCl) ?

Hydrochloric Acid (HCl) is a diatomic molecule as explained above. The two molecules are present in a straight line at an angle of 90o to each other. There is no complex structure involved here. However the components formed from reaction with Hydrochloric Acid (HCl) can have complex structures, for example on reaction with water the hydronium ion formed has a little complex structure with the atoms inclined at different angles with respect to the central oxygen atom. 

Hydrochloric Acid is very commonly used commercially and in Chemical experiments in schools and colleges. The Acid is comparatively easy to handle and doesn’t pose a severe threat when used in diluted form and for a little time of exposure to this Acid. Hydrochloric Acid (HCl) is also found in the stomach of humans and acts as a major factor in helping  digestion in humans. The Acid doesn’t however damage the stomach because of the mucus layer present inside of the human stomach. However upon drinking of beverages or eating of food which results in Acid formation in the stomach, the Acidic balance of the stomach can change and the Hydrochloric Acid (HCl) can become more stronger and concentrated and hence cause Acidity problems or even ulcers. It is therefore advised that water intake for a human should be nominal so that the Hydrochloric Acid (HCl) present in the human stomach doesn’t get too concentrated and cause problems. 

In an organic molecule, the presence of an electron attacking reagent causes electron displacement which leads to polarization of bonds. The effects are magnified in the form of the electromeric effect and hyperconjugation. In this article, students will learn about the two concepts of electromeric effect and hyperconjugation during an attack of a reagent on an organic compound.

Electromeric Effect

The electromeric effect is the instantaneous formation of a dipole molecule of an organic compound. It is a temporary effect and remains as long as the attacking reagent is present. In the electromeric effect, the complete transfer of a mutual pair of π-electrons occurs from one atom to another. The electromeric effect can be broadly classified into two categories:

1. Positive Electromeric Effect (+E) is defined as the transfer of pi-electrons of the atoms to which the attacking reagent gets attached. It can be seen in a reaction between an acid and an alkene. The acid attaches itself to the atom which obtains an electron pair in the transfer. This effect is generally observed when the attacking reagent is an electrophile and the π-electrons get actively transferred towards the positively charged atom.

2. Negative Electromeric Effect (-E) is defined as the transfer of the pi-electrons to the atom to which the attacking reagent is not attached. In this type of effect, the attacking reagent itself loses the electron pair in the transfer. It is generally observed when the attacking reagent is nucleophilic and the π-electrons get transferred to the atom with which the reagent does not bond.

Concept of Hyperconjugation

The concept of hyperconjugation is mostly the same as the electromeric effect; the only factor is that hyperconjugation is a permanent effect. In this effect, localization of σ electrons of C-H bond of an alkali group directly attached either to an unsaturated system’s atom, or an unshared p orbitals atom takes place. 

Hyperconjugation is the reason for the stabilization of glucose so that it allows the spreading of the positive charge. The greater the alkyl group number attached to a positively charged carbon atom, the greater is the stabilization and hyperconjugation interaction of the carbonation.

Causes

Hyperconjugation is basically a stabilization reaction resulting from the interaction between electrons in a σ-bond with either an adjacent partially filled or empty p-orbital or a π-orbital to form an extended molecular orbital.

Applications

There are many applications of hyperconjugation but most importantly it is used in rationalizing numerous chemical phenomena such as the gauche effect, the anomeric effect, the beta-silicon effect, the rotational barrier of ethane, the relative stability of the substituted carbocations & substituted carbon-centered radicals, the vibrational frequency of the exocyclic carbonyl groups, and the thermodynamic Zaitsev’s rule for alkene stability.

For more detailed explanations on the phenomenon of hyperconjugation, log on to ‘s website or download the app. On you can also get related study materials, notes, questions, and solutions for all-around exam preparation for free! 

Currently, we have millions of mills, factories, mining plants, industries, and so on across the world. All these industries use raw materials to form finished goods for consumers. However, in the process of manufacturing, there exist some materials which are rendered useless.

These constitute an industrial waste. There are many industrial waste types. A few different industrial solid waste examples are given as paints, metals, sandpaper, ash, slag, radioactive wastes, and more. Here, we will discuss various types of industrial wastes, including their disposals.

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Types of Industrial Waste

Industrial waste is categorized into 2 forms as, biodegradable and non-biodegradable, which are explained briefly below:

1. Biodegradable

These industrial wastes are the ones that can be decomposed into non-poisonous matter by some microorganisms’ action. They are also comparable to house wastes. These are generated from industries like dairy, food processing, slaughterhouses, textile mills, and so on. A few examples are paper, leather, wool, animal bones, wheat, and more. They do not require special treatment, and they are not toxic in nature either. Their treatment processes include composting, combustion, bio-methanation, gasification, and more.

2. Non-biodegradable

These industrial wastes are the ones that cannot be decomposed into non-poisonous substances. A few examples are given as fly ash, plastics, synthetic fibres, silver foil, gypsum, glass objects, radioactive wastes, and more. These are generated by steel and iron plants, chemicals & drugs, fertilizer, and dyes industries. It is also estimated that about 10 – 15 % of the total industrial wastes are hazardous and non-biodegradable. The rate of increase in this waste category is only increasing every year. These wastes are made less harmful and cannot be broken down easily.

Thus, they are also environmental pollutants and cause threats to living organisms. They enter the bodies of plants and animals, causing diseases and accumulate in the environment. However, with technological advancement, various reuse and disposal methods have been developed. Wastes from one particular industry are being treated well and utilized in another industry. For suppose, the cement industry uses the fly ash and slag generated as waste by the steel industries. Incineration and landfill are the other methods for the hazardous wastes which are being resorted to.

Environmental Impact

Typically, power plants and Factories are located near water bodies because of the need for greater quantities of water as an input to the manufacturing process or cooling equipment. Yet, many areas becoming industrialized do not have the technology or resources to dispose of the waste with fewer environmental effects. Commonly, both partially and untreated wastewater are fed back into a near lying body of water. Whereas, chemicals, sewage, metals released into the water bodies directly affect marine ecosystems, including the health who depend on the waters as drinking or food water sources. 

Also, the wastewater toxins can kill off marine life or cause differential degrees of illness to the ones who consume these marine animals, based on the contaminant. Chemicals and Metals released into the water bodies affect the marine ecosystems.

Air Pollution

Another prominent effect of industrial waste is given as air pollution resulting from the burning of fossil fuels. This affects many people’s lives since this spreads illnesses, and this issue has been widespread over time. Many environmental issues comprise a devastating effect on third-world countries since they don’t have sufficient resources to solve this specific issue. This also affects soil quality because farmers always have to try and deal with this massive issue.

In addition to this, nitrogen dioxide became a common air pollutant found in the air. These air pollutants hold a devastating effect on the human population due to the cause of their sicknesses. Also, ammonia causes several respiratory problems, contracted from the air. In addition, there is also a chance to effect with Bronchitis or Pneumonia, in which both being very dangerous.

The World Health Organization (WHO) has stated: air pollution is one of the worst risks concerning human health. This pollution has been around for a longer period and indoor air pollution has become a risk for humans. This air pollution type is caused by solid fuels burning mostly from heating or cooking.

Water Pollution

Water Pollution is one of the most devastating effects of industrial waste. For most of the industrial processes, a heavy amount of water can be used, which comes in contact with uncountable harmful chemicals. In general, these chemicals are radioactive materials or metals. These affect the environment very heavily because most of the waste ends up in rivers, lakes, or oceans. Resultantly, water becomes polluted, posing a health hazard to all. Farmers completely rely on this water. But if the water is more polluted, then the produced crops can become resultantly polluted.

These effects society’s health too because if the industrial companies cannot clear their waste, this begins to affect the human and animals life. The health of sea creatures is affected because their lives turn endangered due to this polluted water. Water pollution can also have devastating effects on the human body. The primary ones are infections from parasites, chemicals, and bacteria.