Category: Chemistry Notes PPT

What is Potassium Iodide (KI)?

Potassium iodide is described as an inorganic chemical compound which is denoted by the chemical formula – KI. This compound is defined as a metal-halide salt featuring an ionic bond between potassium cation (K+) and iodide anion (I–). This compound is colorless to white, and it appears as cubical crystals or white or powder granules. It has a saline taste and is highly bitter.

This compound is prepared using iodine and mixing potassium hydroxide. It is also one of the safe and most effective medicines required in a health system, and it is on the list of the World Health Organization of Essential Medicines.

Potassium Iodide Structure (KI Structure)

A potassium iodide molecule contains one iodide anion and one potassium cation, which are held together with an ionic bond. The structure of a Potassium Iodide molecule can be illustrated below.

Properties of Potassium Iodide

Let us look at the properties of Potassium Iodide below:

Physical Properties of Potassium Iodide

Chemical Properties of Potassium Iodide

Potassium iodide compound can be oxidized into an I2 molecule by introducing an oxidizing agent to it. One of the examples of such a reaction is given below:

2KI + Cl2 → 2 KCl + I2

This compound can be used as an iodide source in many organic synthesis reactions. One such example is given as the synthesis of aryl iodides from the arene’s diazonium salts.

Benefit of Taking Potassium Iodide Compound During a Radiological Accident

• It is assumed that the ‘accident’ produces notable amounts of iodine’s radioactive isotopes (such as I-131 and I-125), and those get into the supply of food. They would then enter into the body and be taken up by the thyroid gland, which would become non-functional or cancerous.

• By taking the KI compound, the thyroid gland would become saturated with Iodine, and for a while, quit taking up new (which is radioactive) Iodine. And then the thyroid gland would be saved.

• Also, it is not completely clear how this would normally take place and whether it would be much useful to that of a fart in a whirlwind.

• First, the radio-Iodine injury would take place slowly, and if the medical facilities still existed, treatment is available for the injury correction. Also, many do not know how many people would experience this specific injury mode.

• And also, it does not do anything for the people exposed to radio-cesium, Strontium-90, and more related.

Saturated Potassium Iodide Solution

A saturated solution is defined as a solution that contains a similar amount of potassium iodide salt as would be in equilibrium with undissolved salt. It means this is a solution that we represent by the equilibrium.

KI(s) ⇌ K++I−

Uses of Potassium Iodide

Let us discuss the use of potassium iodide as follows:

Medical Uses

Dietary Supplement

Potassium iodide can be used in the human diet and also as a nutritional supplement in animal feeds. It is the most common additive for the latter used to “iodize” table salt (which is a public health measure to prevent iodine deficiency in populations that get little seafood). Also, iodide oxidation causes a slow loss of iodine content from the iodized salts exposed to excess air.

Thyroid Protection

Thyroid iodide compound uptake blockade with potassium iodide can be used in nuclear he medicine scintigraphy and some radioiodinated compound therapy that are not targeted to the thyroid, like iobenguane (MIBG), which can be used either to image or treat the iodinated fibrinogen or neural tissue tumors, which is used in the fibrinogen scans in clotting investigation. These compounds consist of iodine, but not in the form of iodide.

Nuclear Accidents

The U.S. Food and Drug Administration, in 1982, has approved potassium iodide to protect thyroid glands from radioactive iodine by involving fission emergencies or accidents. In an accidental attack or event in nuclear bomb fallout or on a nuclear power plant, volatile fission product radionuclides can be released. Out of these products, 131 (Iodine-131) is the most common and is specifically much dangerous to the thyroid gland since it can lead to thyroid cancer.

Side Effects of Potassium Iodide

There is a reason for caution by prescribing the ingestion of a high dose of iodate and potassium iodide, as their unnecessary usage can cause conditions like the trigger, Jod-Basedow phenomenon, and/or hypothyroidism and worsen hyperthyroidism, and then causes either temporary or even permanent thyroid conditions. Also, it can cause sialadenitis (which is an inflammation of the salivary gland), rashes, and gastrointestinal disturbances. Also, potassium iodide compound is not recommended for people having hypocomplementemic vasculitis and dermatitis herpetiformis – conditions that are linked to iodine sensitivity risk.

Alkenes are the hydrocarbons that contain a double bond between any two adjacent or adjoining carbon atoms. The structure of alkene is such that the number of hydrogen atoms is twice the number of carbon atoms. Alkenes form a homologous series, hence, the general formula of an alkene is stated as CnH2n. The simplest alkene which has one double bond in its structure is ethene, C2H4. Alkenes have important industrial uses, and also play an important role in our everyday lives.  

There are various methods to prepare an alkene. The most commonly used ones are explained below.  

Methods of Preparation of Alkenes 

Preparation of Alkenes From Alkynes  

Alkynes are hydrocarbons containing a triple bond between any two adjoining carbon atoms. Alkenes can be prepared from alkynes by carrying out hydrogenation in the presence of palletised charcoal. The charcoal which is used in this reaction has been moderately deactivated. Lindlar catalyst is palladium on calcium carbonate which has been deactivated by lead acetate to stop further hydrogenation. These alkenes will have a cis- form. To obtain a trans- alkene, these alkynes should be made to react with sodium in liquid ammonia.  

                                                                  (Δ, Lindlar catalyst/ Pd/C)  

                                            CH≡ CH + H2      ——————->      CH2=CH2

                                            Ethyne                                                Ethene 

                                                                            (Pd/C) 

                                                   RC≡ CH + H2  ———> RCH=CH2 

                                                    Alkyne                           Alkene        

                                                                                      

                                                                      (Pd/C) 

                                         CH3-C≡CH + H2 ————>  CH3-CH=CH2  

                                           Propyne                                   Propene

Preparation of Alkenes From Alkyl Halides 

In order to form alkenes from alkyl halides, dehydrohalogenation is performed. Alkyl halides have to be heated in the presence of alcoholic KOH. Alcoholic KOH is obtained when potassium hydroxide is dissolved in alcohol. As the reaction takes place, one molecule of halogen acid is eliminated, and a double bond is formed. The rate at which the reaction will proceed will be determined by the alkyl group and the attached halogen group.  This reaction is also called beta elimination, as the halo group is removed from the alpha carbon while the hydrogen atom is removed from the beta carbon.  

                                  CH3 – CH2X ——> CH2=CH2 (alcoholic KOH,   -HX) 

                                   (X = Cl, Br, I)              (ethene) 

The rate of the reaction is determined by the alkyl group and the type of halogen atom. In this case, the order is iodine > bromine > chlorine. According to the alkyl group, the reaction rate is tertiary > secondary > primary.

Preparation of Alkenes From Vicinal Dihalides 

In vicinal dihalides, two halogen groups are attached to two adjoining carbon atoms in a compound.  In geminal dihalides, the two halogens are attached to the same carbon atom. 

When this dihalide undergoes a reaction with zinc or sodium iodide in acetone, the halogen groups attach to form a compound with zinc or sodium, leading to the formation of a double bond between those two carbon atoms. This reaction is called dehalogenation.  

CH2Br – CH2Br  + NaI  ———>  CH2=CH2 +I2 + 2NaBr ( acetone) 

CH2Br – CH2Br +Zn  ———-> CH2=CH2  + ZnBr2   

 

β Elimination Processes

In which two atoms on adjacent carbon atoms are removed, resulting in the production of a double bond, are commonly used to make alkenes. 

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Alcohols are dehydrated, alkyl halides are dehydrohalogenation, and alkanes are halogenated as part of the process. 

Dehydration of Alcohol  

When an alcohol molecule is heated in the presence of a strong mineral acid, a molecule of water is removed from the molecule. The adjacent carbon atoms that have lost the hydrogen ion and the hydroxide group form a double bond. 

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The steps in this dehydration reaction’s mechanism are as follows.  

Protonation of the alcohol is the first step. 

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This step is a simple acid‐base reaction, which results in the formation of an oxonium ion, a positively charged oxygen atom. 

Dissociation of the Oxonium Ion. 

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The oxonium ion dissociates into a carbocation, a positively charged carbon atom that is an unstable intermediate. 

Deprotonation of the Carbocation. 

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The carbocation’s positively charged end carbon attracts electrons in the overlap region, which bonds it to the adjacent carbon. The carbon becomes slightly positive as a result of the electron movement, which attracts electrons in the overlap regions
of all other atoms bonded to it. As a result, the hydrogen on the carbon becomes slightly acidic, allowing it to be removed as a proton in an acid-base reaction. 

  

Zaitsev  Rule

An alcohol dehydration reaction, in which hydrogen atoms are lost from two different carbons on the carbocation, may be able to create a double bond in some cases. The more highly substituted alkene, that is, the alkene with the most substituents on the carbon atoms of the double bond, is always the major product, according to the Zaitsev rule. The following products are formed during the dehydration reaction of 2butanol. 

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According to the Zaitsev rule, the main product is 2butene. It is worth noting that each carbon atom in the double bond of 2butene has one methyl group attached to it. In the case of 1butene, one carbon atom of the double bond has one substituent (the ethyl group), while the other has none. 

  

Carbocation Rearrangement. 

Rearrangement of carbocations In alcohol dehydration, the carbocation may rearrange to form more stable arrangements. The dehydration of 2 methyl 3 pentanols, for example, results in the formation of three alkenes. The mechanism of the reaction reveals that the extra compound is formed as a result of the carbocation intermediate being rearranged. 

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The intermediate carbocation is rearranged to form the 2 methyl1 pentene molecule. 

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A Hydride Ion (H: – ) Movement 

results in the formation of a more stable carbocation. Carbocations, like carbon atoms, are classified as primary, secondary, and tertiary. A primary carbocation has one alkyl group attached to it, a secondary carbocation has two alkyl groups attached to it, and a tertiary carbocation has three alkyl groups attached to it. 

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Alkyl groups can theoretically “push” electrons away from themselves. This is known as the inductive effect. The more alkyl groups that “push” electrons toward a positively charged carbon atom, the more stable the intermediate carbocation. This increase instability is due to charge density delocalization. A charge on an atom causes it to be stressed. The more the stress is distributed across the molecule, the lower the charge density on any one atom becomes, reducing stress. The ion becomes more stable as the stress decreases. Thus, tertiary carbocations have three alkyl groups on which to delocalize the positive charge, whereas secondary carbocations only have two alkyl groups on which to delocalize the positive charge. Secondary carbocations are more stable than primary carbocations for the same reason. 

  

Alkyl groups, in reality, do not “push” electrons away from themselves, but rather have electrons removed from them. When an atom gains a positive charge and transforms into an ion, its electronegativity changes. The location of the overlap region relative to each carbon atom in the original bond between two carbon atoms is determined in part by the electronegativity of the two atoms. The overlap region moves closer to the more electronegative, positively charged carbon atom as the electronegativity of one of the carbon atoms increases due to ion formation. This electron density rearrangement results in a partial positive charge on the neighboring carbon. The charge gained by the second carbon atom equals the charge lost by the fully charged carbon atom. As a result, the charge is delocalized across the two carbons. 

 

Alkyl Halide Dehydrohalogenation 

Another elimination reaction is the dehydrohalogenation of alkyl halides, which involves the loss of hydrogen and a halide from an alkyl halide (RX). Normally, dehydrohalogenation is accomplished by reacting the alkyl halide with a strong base, such as sodium ethoxide. 

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This reaction also follows the Zaitsev rule, so the major product in the reaction of 2chlorobutane with sodium ethoxide is 2butene. 

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The following mechanism governs dehydrohalogenation reactions. 

1. An acid-base reaction occurs when a strong base removes a slightly acidic hydrogen proton from an alkyl halide. 

2. Electrons from the broken hydrogen carbon bond are drawn to the slightly positive carbon atom connected to the chlorine atom. The halogen atom breaks free as these electrons approach the second carbon, resulting in the formation of the double bond. This mechanism is depicted in the diagram below. 

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Fun Facts About Alkenes 

1. Alkenes can exist in all three states: solid, liquid, and gas. The first three alkenes are gaseous, the next fourteen are in the liquid state. As the molar mass increases further, they exist in the solid-state.  

2. Alkenes are not soluble in water due to the existence of weak van der Waal forces. 

3. Alkenes, however, are soluble in organic solvents such as benzene and acetone.  

4. Higher the molar mass of a given alkene, greater will be its boiling point. Hence, the boiling points of higher alkenes are quite high.  

5. The functional group attached to the alkene is the determinant of its polarity.  

6. Being unsaturated in nature, alkenes are highly reactive compounds. Most of these reactions will take place at the site of the double bond, that is at the two carbon atoms between which the double bond is placed. They can easily undergo addition and oxidation reactions.

Nitrogen was discovered in 1772 by Daniel Rutherford, a Scottish scientist. Lavoisier established its elemental nature and named it azote. The present name nitrogen is derived from nitre which is a well known nitrogenous compound. Nitrogen is the first element of group 15 of the periodic table and has electronic configuration 1s22s22p3. The molecular form of nitrogen is referred to as N2. The method of preparation of nitrogen and N2 (Dinitrogen) is the same. They have the same physical and chemical properties as well as uses. Nitrogen is an essential constituent of all vegetable and animal proteins which are vital for life processes. 

Laboratory Method of Preparation of Dinitrogen (N2)

In the laboratory, N2 is prepared by heating an aqueous solution of ammonium chloride and sodium nitrite.

NH4Cl(aq)+NaNO2(aq) → NaCl(aq)+2H2O(l)+N2(g)

Small amounts of nitric oxide and nitric acid are also formed in this reaction. The N2 thus obtained is purified by passing the evolved gas through an aqueous sulphuric acid solution containing potassium dichromate.

Other Methods of Preparation of N2

By Thermal Decomposition of Ammonium Dichromate 

When red crystals of ammonium dichromate are heated, a violent reaction takes place which is accompanied by flashes of light and evolution of nitrogen.

(NH4)2Cr2O7 →  N2+4H2O+Cr2O3

By Oxidation of Ammonia

When ammonia is oxidized by a red hot copper oxide or by chlorine, nitrogen is obtained.

2NH3+3CuO → N2+3H2O+3Cu

8NH3+3Cl2 → N2+6NH4Cl

By Thermal Decomposition of Sodium Azide

Very pure nitrogen can be obtained by heating sodium or barium azide.

2NaN3 → 2Na+3N2

Ba(N3)2 → Ba+3N2

Manufacturing of N2

Commercially, N2 is prepared by the fractional distillation of liquid air. 

Properties of Dinitrogen (N2)

Physical Properties of Dinitrogen (N2)

• It is a colorless, odorless, and tasteless gas.

• It is non-poisonous but animals die in an atmosphere of nitrogen for want of oxygen.

• It has very low solubility in water (23.2 cm3 per litre of water at and pressure)

• Its melting and boiling points are 63.2K and 77.2K respectively.

Chemical Properties of Dinitrogen (N2)

• N2 is almost non-reactive at ordinary temperatures. It neither burns nor supports combustion. The chemical inertness of N2 at ordinary temperatures is due to the high stability of the molecule.

• In a molecule of N2, the two nitrogen atoms are linked together by a triple bond. The triple bond has a very high bond enthalpy(amount of heat energy required to break a chemical bond) . Due to very high bond dissociation enthalpy, N2 is almost unreactive towards most of the reagents. 

• However, at high temperatures, it combines with some metals and non-metals to form ionic and covalent compounds called nitrides. Some important chemical reactions of N2 are given below.

Combination with Electropositive Metals

N2 combines with some highly electropositive metals at high temperatures forming their nitrides. Lithium nitride forms slowly at ordinary temperatures but rapidly at higher temperatures. Magnesium and aluminum continue burning in an atmosphere of nitrogen forming their nitrides. Calcium, strontium, and barium react with N2 when they are red hot.

6Li+N2→ 2Li3N2

3Mg+N2→ Mg3N2

2Al+N2 →  2AlN

3Ca+N2→  Ca3N2

Combination with O2

N2 combines with O2 in the presence of an electric arc (above 3273K) to form nitric oxide.

N2+O2→ 2NO

Equations

1. What happens when N2 combines with H2?

N2 reacts with H2 at 725K under a pressure of 200 atmospheres in presence of a catalyst (finely divided iron and molybdenum).

N2+3H2→ 2NH3

2. Write chemical equations for the reaction of N2 with Alumina and Calcium Carbide.

Al2O3+N2+3C → 2AlN+3CO

CaC2+N2→ CaCN2+C

CaCN2 or Calcium cyanide is an important fertilizer.

Uses of Dinitrogen (N2)

• The main use of N2 is in the manufacturing of ammonia. It is also used in the p
  reparation of some other important chemicals such as calcium cyanide, nitric acid, etc.

• It is used for providing an inert atmosphere in several metallurgical operations.

• Liquid nitrogen is used as a refrigerant to preserve biological materials and in freezing food articles. It is also used in cryosurgery.

• It is used as an inert diluent for reactive chemicals.

Industrial Applications of Nitrogen 

The main use of nitrogen in the industrial world is to create ammonia required for explosives, fertilisers, and other materials. However, there are plenty of other uses of nitrogen in different industries. Whether it is pharmaceuticals or food packaging, nitrogen is an essential element in many areas. Mentioned below are the uses of nitrogen in different industries: 

1. Food Packaging

Nitrogen is used in many food production processes to maintain the quality of food or beverage. It has become a common practice for manufacturers to use compressed nitrogen to replace oxygen while packing perishable food items. In the absence of oxygen, food items such as vegetables, fruits, meats, and snacks can last longer. Moreover, nitrogen also prevents food from getting damaged during transport. 

2. Car Tires 

Car tires inflated with nitrogen perform much better than the ones inflated with compressed air. Using nitrogen in your car tires can improve the fuel economy of your vehicle. Unlike compressed air, nitrogen struggles to escape from the tire’s cavity, which ensures that the pressure inside the tire remains the same for a long time. At an ideal pressure, the car’s engine works more smoothly. 

Not only the fuel economy, but nitrogen can also enhance the durability of your car tires. Compressed air contains water vapour that leads to rustiness in the wheels. However, nitrogen eliminates the risk of corrosion and enhances the lifespan of the tire. 

Moreover,  tires inflated with nitrogen offer more safety than the ones that have compressed air in them. No matter what the weather condition is, nitrogen inflated tires are the best choice. These tires ensure consistent performance in dry and wet conditions. If you often drive on highways, nitrogen-filled tires will help you smoothen the ride and improve your driving experience. 

3. Chemical Blanketing 

Many manufacturers use nitrogen in highly explosive chemical plants to displace oxygen from the production process. It is usually used to prevent explosions and fires in a dangerous environment such as factories, manufacturing facilities, and chemical plants. By lowering the level of oxygen, one can prevent explosions in their manufacturing facilities. 

4. Electronics

While assembling electronic devices, nitrogen is used to combine two components of the device permanently. This process is also known as soldering. In this process, nitrogen is used to provide a cleaner break away from the electric bond by reducing the surface tension. Besides this, nitrogen also plays a pivotal role in preventing computers from overheating. 

5. Laboratory

In laboratories, researchers or scientists require a specific environment to carry out tests and results accurately. For this, nitrogen is used to control oxygen levels, temperature, and humidity. This way, the gas helps in maintaining the perfect atmosphere to perform sensitive procedures and tests using heavy equipment. Other than that, many types of lab equipment require nitrogen for purging too. 

6. Laser Cutting 

Since nitrogen can be used for purging, it has become an essential element for the entire steel industry. The nitrogen gas is used to blow away molten residue and help in producing a durable and stronger stainless or aluminised steel product, which is resistant to corrosion. 

It is a mixture of minerals, organic matter, liquids, gases, small organisms that altogether support life. It is the upper layer of the earth’s surface composed of a mixture of organic remains, clay, and rock materials on which plants grow. It supports plant life and growth. It continually undergoes development by numerous physical, chemical, and biological processes, which include weathering and erosion. The density of soil is 1.6 g/cm3.

Physical Properties of Soil

Physical properties of soil include colour, texture, structure, porosity, density, temperature, and air. The colours of soil vary widely from place to place and indicate some properties like organic matter, water, and redox conditions of the soil. Soil texture, structure, porosity, density, are related to the types of soil particles and their arrangement.

Soil Texture: Soil texture definition (such as loam, sandy loam, or clay) refers to the proportion of sand, silt, and clay-sized particles that make up the mineral fraction of the soil. Sand and silt are of no importance to the soil as they don’t contribute to the soil’s ability to restore water and nutrients. Clay is an active part of soil texture as it has a small size and has a large amount of surface area per unit mass and it helps in storing water and ions. The texture of soil helps to know about the amount of water that soil can hold, the rate of water movement through the soil, how workable and fertile the soil is.

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Absorption of Water:  Soil is able to absorb water because of its porosity. Water holding capacity is different for different types of soils. Sand absorbs less water than clay. Sandy soil water holding capacity is less than clay soil and loamy soil. Clay soil holds more water than sandy soil.

Soil Colour: Soils are of different colours (brown, yellow, red) depending on oxidised or ferric iron compounds. The darker the colour of the soil, the more organic content it contains. The red colour of the soil is due to the presence of iron oxide and The black colour soil is rich in minerals and humus.

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Soil Horizon

The soil is divided into different horizons from top to bottom:

• A-Horizon: The uppermost layer of soil is called topsoil. This layer mostly contains minerals from parent material with organic matter. A good material for plants and other organisms to live is found on this horizon.

• B-Horizon: This is the second layer from the top and is a little rich in humus and it supports moisture. This layer consists of clay, silt, nutrients, and weathered rocks. Minerals present in this layer are more in comparison to the top layer.

• C-Horizon: This is the third most layer from the top, and it consists of small pieces of rocks broken down due to weathering.

• Bedrock: This is the last layer of the soil and consists of layers of solid unweathered rock.

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The pH of Soil

Soil can be acidic, alkaline, or neutral. Some plants grow well in acidic soil such as potatoes. Plants like the bean, garlic grow well in the basic type of soil. Carrots and lettuce prefer neutral soil. The pH of soil under the chemical properties of soil. Other chemical properties include Calcium carbonate content, Soil sodicity, Soil nitrogen, etc.

Soil Structure Definition

Soil structure can be defined as the way individual particles of sand, silt, and clay are assembled together. Single particles when assembled appear as larger particles. These are called aggregates. Humus is a major deciding factor to know about the structure of soil because it causes the soil to become more porous and allows water and air to penetrate deep underground. 

Types of Soil Structure

What is Soil Conservation?

Soil conservation is the process of prevention of loss of the topmost layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization, or other chemical soil contamination.  By conserving soil we can preserve the fertility of the soil. Few methods of conserve them are: 

Formation of Soil

The formation of soil is a complex natural process. The uppermost layer of the earth crust is made up of soil. Soil contains minerals, organic matter and living organisms. The formation of soil takes place by breaking of rocks by physical and chemical agents.

There are three agents of soil formation which are as following :

• Mechanical Processes: The formation of soil when happens due to any of the mechanical forces, then these are called mechanical Processes. For example wind and rain.

• Chemical Processes: Chemical processes are those Processes in which rocks break due to chemical reactions.

• Biological Processes: Biological processes are those processes in which any biological change results in the formation of soil. For example the lichens present on the rocks a certain chemical which results in the formation of soil.

For more this type of informative article you. And refer to . is a platform where you can find all of study material and important questions at a single place. 

Quantitative chemical analysis is the method of determining the absolute or relative abundance of one, several, or mostly all particular substances that are present in a sample. It is widely used in analytical chemistry and the methods that come under this umbrella are used to conduct scientific experiments, and also determine various industrial production aspects. The properties that are used to determine the quantitative analysis chemistry are both physical and chemical properties. The most common description of the quantitative analysis chemistry is given by the concentration of the ore. 

Different Methods of Quantitative Analysis

The study of the absolute and relative abundance in a given sample, for the determination of the specific properties of certain substances present in the sample. For best use of quantitative analysis chemistry and chemical, methods have been developed so much that there are numerous methods and techniques to identify and characterize any sample quantitatively. Although there are numerous methods and techniques developed, knowing a sample or the composition of the sample is of significant importance to eliminate any possible tests for further characterisation. Two of the common classifications under which various methods of analysis which students can also find in any textbook of quantitative chemical analysis. They are classified as under:

• Gravimetric Analysis: These are a set of different methods that are used to determine the characteristics of an analyte based on the mass. The principle that works behind these methods is that when an analyte’s mass is known or determined as a unique singular entity the known value of the mass then it can be used to determine the mass of the analyte in a mixture, as long as relative quantities of other analytes in the mixture is known. 

• Volumetric Analysis: These are the set of methods that involve the concept of concentration of a particular analyte in a solution. The main principle in these methods is the functioning of a known reaction and the result of the reaction. A known compound that induces a particular reaction leading to an end product is used for measurement of the concentration of the unknown in the solution. 

The methods used in the gravimetric analysis techniques provide more accurate results and more accurate data for the composition of the sample. The drawback is that it takes a long time to analyse samples based on the gravimetric methods. This is in contrast to the volumetric methods of quantitative analysis analytical chemistry provides for. The quantitative inorganic analysis is mostly based on the concepts of the concentration such as molarity and their relation to volumes and provides satisfactory results within a short period of time. The volumetric analysis is simply a titration reaction that can either produce neutralised salt products, precipitates, complexes, or redox products which can be obtained instantly or in a much lesser time as compared to the gravimetric analytical methods. 

The benefit of quantitative chemical analysis is that they are very generalised in nature. They can be applied to understand a wide range of analytes especially while performing quantitative inorganic analysis. Examples of some of these general characteristics of the methods are stated below:

• Neutralisation Reaction: A reaction between an acid and a base produces salt and water as products. This is known as a neutralisation reaction. 

• Precipitation Reaction: A reaction in which the end result is a highly insoluble complex or compound that falls out of the solution and precipitates is known as a precipitation reaction. The standard solution widely used in these methods is silver nitrate that is used as a reagent for the reaction. These methods are also known as argentometry. 

• Complex Reaction: These titration reactions that occur in-between the metal ions and a standard solution give products that are complexes of the metal ion. In most cases, the standard solution that is used is the EDTA (Ethylene Diamine Tetra Acetic Acid). 

• Redox Reaction: Redox titration reaction is carried out in between an oxidising agent and a reducing agent.

Other examples of methods that are part of the quantitative chemical analysis are the Leibig method or Duma’s method or Kjeldahl’s method and the Carius method for the estimation of the organic compounds. These quantitative analysis methods can also be applied for the mass spectrometry on the biological samples that can be determined by the relative abundance of the ratio of the specific proteins, and indications of diseases like cancer. 

Other Analytical Methods in Chemistry

The other most common and fundamental methods in chemistry are the qualitative analytical methods. Students, as they learn, will study methods included in both the qualitative and quantitative analysis chemistry class has to offer. The qualitative methods are used for the determination of the quality of a sample and a particular analyte in a sample. The IUPAC (International Union of Pure and Applied Chemistry) defines both the quantitative and qualitative methods as follows:

“The general expression Quantitative Analysis […] refers to the analysis in which substances are identified or classified on the basis of their chemical or physical properties, such as chemical reactivity, solubility, molecular weight, melting point, radioactivity properties (emission, absorption), mass spectra, nuclear half-life, etc.  Quantitative Analysis refers to analyses in which the amount or concentration of an analyte may be determined (estimated) and expressed as a numerical value in appropriate units. Qualitative Analysis may take place with Quantitative Analysis, But Quantitative Analysis requires the identification (qualification) of the analyte.For which numerical estimates are given.”  

Spectroscopy techniques such as IR (Infra-red) spectroscopy or UV (Ultra-violet) spectroscopy are used to understand and assert the qualitative properties of a sample. It can also be very accurately determined in the ranges of micro-molars or nano-molars using methods of NMR (Nuclear Magnetic Resonance). 

A chemical reaction is a process that results in the chemical transformation of one set of chemical substances into another set of chemical substances. Chemical reactions are typically defined as changes in the positions of electrons in the formation and breaking of chemical bonds between atoms, with no change in the nuclei (no change in the elements present), and can be explained using a chemical equation.

This article will study intermediate chemistry, reaction intermediate and examples of inter chemistry.

What is a Reaction Intermediate?

Any chemical substance formed during the conversion of a reactant to a product is referred to as a chemical intermediate. Most synthetic processes entail a series of steps that turn a readily available and often inexpensive material into a desired product. Intermediates are all the substances generated by one step and used in a subsequent step.

Aside from substances that can be recovered as products if the reaction is stopped at the point where the intermediate, unstable molecules are produced, some chemical substances are known or suspected to be intermediates, even if they have not yet been isolated. Free radicals, carbenes, carbonium ions, and carbanions are some of the more well-studied classes of theoretically unstable intermediates. These intermediates are highly reactive fragments of molecules that are normally uncombined for just a few seconds.

For example, consider this hypothetical stepwise reaction:

A + B → C + D

The reaction includes these elementary steps:

A + B → X*

X* → C + D

The chemical species X* is an intermediate.

Intermediate Compound

1. An intermediate, according to the IUPAC Gold Book, is a molecular entity (atom, ion, molecule, etc.) that is formed (directly or indirectly) from the reactants and reacts further to give (directly or indirectly) the products of a chemical reaction. The lifetime condition distinguishes actual, chemically distinct intermediates from vibrational states or transition states with lifetimes similar to those of molecular vibration, and thus intermediates correspond to potential energy minima of depth greater than available thermal energy arising from temperature (RT, where R is gas constant and T is temperature).

2. Since many intermediates have a short half-life and are highly reactive, their concentration in the reaction mixture is low. Definitions like fast/slow, short/long-lived are subjective, and rely on the relative rates of all the reactions involved, as is often the case when discussing chemical kinetics. Species that are unstable in one reaction mechanism may be stable in another, and molecular entities that are intermediates in one reaction mechanism may be stable enough to be detected, classified, isolated, or used as reactants in (or products of) other reactions. Free radicals or unstable ions are often used as reaction intermediates. Since oxidising radicals (OOH and OH) are so reactive in combustion reactions, they must be generated at a high temperature to compensate for their absence, or the combustion reaction will stop.

3. When the reaction’s necessary conditions are no longer met, the intermediates react further and are no longer present in the reaction mixture. In certain processes, several reactions are carried out in the same batch. In the esterification of a diol, for example, a monoester product is formed first, which can be isolated, but the same reactants and conditions facilitate the monoester’s conversion to a diester. The lifespan of such a “intermediate” is significantly reduced.

Types of Reaction Intermediate in Organic Chemistry

Given are the Examples of Intermediate Chemistry

1. Carbanion

A carbanion (also called a carbonium ion in some texts) is a reaction intermediate in organic chemistry that has a negative one charge on a carbon atom. Carbanions are formed when an organic compound is treated with a very strong base. Consider the reaction of butane with a base as an example. A carbanion is formed when the base removes a hydrogen atom from butane.

Carbanions are highly reactive, and they don’t survive long after they’ve been formed in a chemical reaction. They usually go on to react with a positive species in the reaction to form the reaction’s final product. This makes sense because we’re forming a negatively charged intermediate, which means it’ll be drawn to something with a positive charge.

2. Free Radical

Free radicals are another common form of reaction intermediate. A single unpaired electron exists in free radicals. When a covalent bond (a bond made up of two electrons) is broken, each atom takes one of the bond’s electrons. If a carbon-hydrogen bond in methane is broken, for example, one of the bond’s electrons goes to carbon and the other to hydrogen. Notice how we use single dots on the atom where the radical is positioned to reflect free radicals.

Did You Know?

There are no intermediate products in the elementary reaction, which is the smallest division into which a chemical reaction can be decomposed. The majority of experimentally observed reactions are made up of a series of elementary reactions that happen in a parallel or sequential order. The reaction mechanism is the actual sequence of the individual elementary reactions. Because of the low probability of many molecules meeting at the same time, an elementary reaction only requires a few molecules, typically one or two.

Unimolecular and bimolecular reactions are the most important elementary reactions. In a unimolecular reaction, only one molecule is involved; it is converted into one or more other molecules through isomerization or dissociation. The addition of energy in the form of heat or light is needed for such reactions.