Category: Chemistry Notes PPT

What Do You Mean By Thermal Conductivity?

In order to understand the term thermal conductivity, we need to understand first, what conductivity. Thermal conductivity of a material we mean, the measure of its ability to conduct heat. It is commonly denoted by k or λ.

The defining equation for thermal conductivity q = –k⛛T, where q is the heat flux, k is the thermal conductivity, and ⛛T is the temperature gradient which is known as Fourier’s Law for heat conduction. It is commonly expressed as a scalar, the most general form of thermal conductivity is a second-rank tensor. In spite of that, the tensorial description only becomes necessary in materials that are anisotropic.

What Do You Mean By The Thermal Conductivity Of Copper?

The thermal conductivity of copper is the measure of its ability to conduct heat, it means the transfer of heat from one body to another, the thermal conductivity of a substance, k, is an intensive property(a property of a material that does not depend on the amount or shape of the material, a property of the material at a specific point in space.) that indicates its ability to conduct heat. It is often measured with laser flash analysis. Alternative measurements are also established. Due to the composition, mixtures may have variable thermal conductivities. Note that for gases in usual conditions, heat transfer by advection (caused by convection or turbulence for instance) is the dominant mechanism compared to conduction.

If we see the thermal conductivity of pure copper, it is about 400 watts per meter kelvin. This implies that a plate of copper with area A and thickness L whose faces are kept at a constant relative temperature difference of ΔT kelvin will conduct heat at a rate of 400⋅A/L⋅ΔT joules per second. For manufacturing conductive appliances in the United States, copper is the most commonly used metal. It has a high melting point and a moderate corrosion rate. It is also a very effective metal for minimizing energy loss during heat transfer. Appliances like metal pans, hot water pipes, and car radiators utilize the conductive properties of copper.

A variety of options are available to measure thermal conductivity, each of them is suitable for a limited range of materials, depending on the thermal properties and temperature.  By thermal conduction, we mean that it is the transfer of heat from one part of a body to another with which it is in contact and thermal conductivity is a measure of the ability of a material to conduct heat, often denoted by k, λ, or к. Heat transferred depends upon the magnitude of the temperature gradient and the specific thermal characteristics of the material.

Different Methods To Test Out The Thermal Conductivity Of Copper: –

• Steady-state Method: – In General, steady-state techniques perform a measurement when the temperature of the material measured does not change with time. Therefore the signal analysis is straightforward (steady-state implies constant signals). The only downside is that a well-engineered experimental setup is usually needed.

• Transient Methods: – In this method measurement of thermal conductivity is done during the process of heating up. Therefore the measurements can be made quickly, which is an advantage. They are usually carried out by needle probes.

As copper allows heat to pass through it quickly, therefore it is used in many applications where quick heat transfer is important. These include:

Applications of Thermal Conductivity of Copper

Did You Know?

1. In copper metals, copper atoms are closely packed together.

2. Every copper atom loses one electron and becomes a positive ion which defines that copper is a lattice of positive copper ions with free electrons moving between them. (The electrons are a bit like the particles of a gas that is free to move within the surfaces of the wire).

3. Since the electrons can move freely through the metal, therefore they are known as free electrons. Free electrons also help copper to be a good conductor of heat and electricity, therefore they are also known as conduction electrons.

4. The copper ions  vibrate (see Figure 1). Notice that they vibrate around the same place whereas the electrons can move through the lattice. This is very important when we connect the wire to a cell.

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Figure 1 – A section of copper wire showing lattice of copper ions. There are also 

free electrons that move through this lattice, like a gas.

5. Copper word is derived from the Latin word ‘cuprum’, which means ‘ore of Cyprus’. That is we use the chemical symbol for copper as Cu.

Tin is an element belonging to the p-block. It is present in the fourteenth group in the fifth period. In this article we will discuss the tin in detail and cover all important points about tin element like tin formula, The latin name of tin, Sn chemical name, tin scientific name, allotropes of tin, and chemical composition of tin alloys.

Tin Formula

Tin formula represents the symbol of the Tin. Its symbol is “Sn”. Latin name of tin is stannum. Sn chemical name is tin. Tin scientific name is the same as that of tin chemical name. Chemical composition of tin alloys include around 92% of tin, 7% antimony, and 1–2% copper, sometimes with bismuth or silver additions also present. Tin in nature occurs in two forms; organic tin and inorganic tin. Naturally tin found in earth crust. Organic tin forms a major contribution of an anthropogenically generated category of tin. 

Organic tin is more toxic than the inorganic form of the tin. Toxicity of the organic form of the tin depends on the length of the alkyl group chain. Larger the alkyl group chain more will be the hydrophobic nature and more will be the toxic nature of the tin compound. Tin does not act as an essential element for the human body. The route of the tin excretion depends upon the type of the compound and the mode of the exposure. Generally insoluble inorganic compounds of the tin are non-toxic in nature. Toxicity caused by the organic form of the tin causes memory loss or mental disability. 

Characteristics of Tin

• Atomic mass of tin is 118.71u.

• Atomic number of tin is 50.

• Electronic configuration of tin is [Kr]5S24d105p2.

• Its atomic radius is 217 pm.

• Common oxidation state of tin is +4 and +2.

• Its density is 7.287 g/cm3.

• Its melting point is 505.08 K.

• Its boiling point is 2875 K.

• It exists in solid state at normal temperature.

• It is silver-white in colour.

Comparison of Tin with Other Group 14th Elements

Carbon, silicon, germanium, Tin, and lead are the group fourteen elements. All these elements do not react with water. Carbon when steam is heated forms carbon monoxide and hydrogen gas. Tin chloride is a compound of tin. Tin chloride reacts with potassium permanganate (KMnO4) and forms tin tetrachloride as a product. In this reaction tin dichloride gets oxidised from +2 oxidation state to +4 oxidation state. Tin dichloride reacts with potassium dichromate and forms tin tetrachloride and Cr+3 cation (green colour). Tin dichloride reacts with mercuric chloride forms white precipitate of mercurous chloride. When this mercurous chloride again reacts with the tin dichloride forms grey black precipitate of mercury. Tin dichloride reacts with the auric chloride and forms tin tetrachloride and aurous precipitate. 

C, Si, Ge, Sn, Pb + H2O→ No reaction.

C + steam → CO + H2

SnCl2 + KMnO4 → SnCl4 + Mn+2

SnCl2 + K2CrO7 → SnCl4 + Cr+3 (green colour)

SnCl2 + HgCl2 → Hg2Cl2 (white ppt) → Hg (grey black ppt)

SnCl2 + AuCl3 → SnCl4 + Au (precipitate)

Uses of Tin

• It is used in coating of metals for prevention of corrosion.

• It is used in making tin cans.

• It is used in producing window glass.

• Tin used in forming alloys.

• Tin alloys are used in making superconducting wires.

• Tin salts are sprayed on glass to make electrically conductive coatings.

• Stannous fluoride is used in toothpastes.

Allotropes of Tin

Tin exists in three allotropic forms

1. Grey Tin.

2. White Tin (tetragonal).

3. White Tin (rhombic).

White tin exists in tetragonal crystal structure. Grey tin exists in a face centered cubic structure. Tin allotropes can be transformed from one crystal form to another at a specific temperature.

Grey tin is also known as alpha tin. It can be transformed into white tin at 13.2 degrees celsius. White tin can be transformed into brittle tin (rhombic crystals) at 161 degrees celsius.

Harmful Effects of Tin

• Tin causes breathing problems when inhaled.

• Tin shows a property of an irritant. Therefore, it causes irritation to eyes and skin when it comes in contact.

• Tin causes nausea, vomiting, coughing, and shortness of breath.

• Tin can cause pain. Fatigue, and tremors.

• High intake of inorganic form of tin causes anemia.

• Intake of tin causes heart and kidney problems.

Did You Know?

• Tin is a rare element found in the earth crust.

• Tin forms 2 parts per million of the earth crust composition.

• Tin when mixed with copper forms bronze (alloy).

Transesterification is an organic reaction in which an alcohol’s R group is substituted for an ester’s R’ group. In most cases, this is achieved by applying an acid or base catalyst to the reaction mixture. It can also be achieved with the aid of enzyme catalysts (such as lipases). The exchange of an R’ group from alcohol with an R’’ group from an ester in a transesterification reaction is illustrated in the diagram below.

This article will study the transesterification meaning and transesterification process in detail.

When this reaction is catalyzed by an acid catalyst, the carbonyl group is converted by the donation of a proton to it. Base catalysts, on the other hand, take a proton away from the alcohol group, creating a strongly nucleophilic alkoxide ion.

It should be noted that transesterification can be used to produce esters with relatively large alkoxy groups from methyl and ethyl esters. This is normally achieved by heating the ester (methyl or ethyl) with the acid/base catalyst and large alkoxy alcohol, then evaporating the smaller alcohol to push the equilibrium reaction in the desired direction.

Transesterification Mechanism

Here is given transesterification process step by step:

In Basic Medium

Step 1

The basic medium deprotonates the alcohol, which results in the formation of an alkoxide ion. This alkoxide strikes the carbonyl carbon of the ester with a nucleophilic attack, resulting in the formation of an intermediate. As seen in the diagram below, the double bond between the carbonyl carbon and the oxygen is broken, and the negative charge is transferred to the carbonyl oxygen.

Step 2

The initial ester reactant’s R’ group serves as a leaving group, and it is removed from the intermediate. The bond pair of electrons is maintained by the oxygen, resulting in the creation of a new alkoxide. Finally, as shown below, the double bond between the carbonyl carbon and the negatively charged oxygen is reformed.

In Acidic Medium

Step 1

The acidic medium first protonated the carbonyl oxygen. The oxygen becomes more electron-withdrawing as a result of the positive charge, activating the carbonyl carbon against a nucleophilic attack.

Step 2

The nucleophilic nature of the alcohol is due to the presence of two lone pairs on the oxygen. This oxygen binds to the carbonyl carbon via a nucleophilic attack. An intermediate is formed as a result of this.

Step 3

This intermediate undergoes an intramolecular proton transfer, in which the positive charge is transferred from the oxygen of the alcohol to the oxygen of the ester, as shown below.

Step 4

The carbon-oxygen bond is broken because the protonated oxygen acts as a leaving group. The oxygen atom maintains the bond pair, and the positive charge is relayed to the carbonyl oxygen via the carbonyl carbon (the carbon-oxygen double bond is reformed, as illustrated below).

Step 5

The carbon-oxygen bond is broken because the protonated oxygen acts as a leaving group. The oxygen atom maintains the bond pair, and the positive charge is relayed to the carbonyl oxygen via the carbonyl carbon (the carbon-oxygen double bond is reformed, as illustrated below).

Applications of Transesterification

1. Polyester Production

Polyester synthesis is the largest-scale application of transesterification. Diesters are transesterified with diols to form macromolecules in this application. Dimethyl terephthalate and ethylene glycol, for example, react to produce polyethylene terephthalate and methanol, which is then evaporated to speed up the reaction.

2. Methanolysis and Biodiesel Production

Transesterification also includes the reverse reaction, methanolysis. Polyesters have been recycled into individual monomers using this method (see plastic recycling). It’s also used to make biodiesel from fats (triglycerides). One of the first applications was for this conversion. Before World War II, heavy-duty vehicles in South Africa were powered by transesterified vegetable oil (biodiesel).

3. Fat Processing

In the food industry, fat interesterification is used to rearrange the fatty acids of triglycerides in edible fats and vegetable oils. For example, a solid fat with mostly saturated fatty acids could be transesterified with vegetable oil with a lot of unsaturated acids to make a spreadable semi-solid fat with a mix of both kinds of acids.

4. Synthesis

Enol derivatives are difficult to make using other methods, so transesterification is used to make them. Transesterification of vinyl acetate, which is readily available, produces vinyl ethers.

Did You Know?

1. Triglycerides are a type of lipid (fat) found in the bloodstream.

2. Your body transforms any calories it doesn’t need right away into triglycerides when you feed. Triglycerides are contained in the fat cells of your body. Hormones then release triglycerides to provide nutrition in between meals.

3. You may have high triglycerides if you eat more calories than you burn on a regular basis, especially from high-carbohydrate foods (hypertriglyceridemia).

4. High triglyceride levels may contribute to artery hardening or thickening (arteriosclerosis), which increases the risk of stroke, heart attack, and heart disease. Highly high triglycerides can also cause acute pancreas inflammation (pancreatitis).

5. Obesity and metabolic syndrome — a cluster of disorders that involves too much weight around the waist, high blood pressure, high triglycerides, high blood sugar, and abnormal cholesterol levels — are also associated with high triglycerides.

The Trivial Nomenclature system employs a non-systematic approach to organic compound naming. There is no such thing as a set of guidelines for writing the trivial naming of compounds. 

The names of organic substances are simplified using this method. Examples include phenol, acetic acid, and toluene.

The names of compounds designated using trivial nomenclature are frequently significantly shorter and simpler than the matching IUPAC nomenclature. As a result, this system is still relevant today.

Eg. According to the trivial system, tartaric acid is a kind of carboxylic acid that is commonly found in tamarind. 2,3-dihydroxy-1,4-Butanedioic acid would be the IUPAC nomenclature for tartaric acid.

Nomenclature of Organic Compounds

Choosing and naming a parent structure is the first step in naming an organic chemical systematic. In the case of parent hydrides, suffixes can be added to the basic name to indicate the exact structural changes required to form the compound in question.

Unlike systematic names, traditional names such as acetic acid, butane, and pyridine are widely used in industry and academics. Traditional names are kept when they are useful and fit into the broader pattern of systematic nomenclature.

The concept of preferred IUPAC names is described and applied in a methodical way, as well as a fundamentally new principle. The nomenclature that has been used by IUPAC so far has focused on making games that aren’t confusing. This is in line with how the subject has changed over time.

Due to the rapid spread of information and the globalization of human activities, it was judged necessary in 1993 to develop a common language that would be useful in legal situations such as patents, export-import rules, environmental health and safety information, and so on.

Eg. Because the principal way of getting methyl alcohol was to distil it from wood, it was given the name wood spirit under the trivial nomenclature convention.

Scope 

All compounds with carbon as the main ingredient are qualified as organic compounds. The functional or characteristic groups are made up of three elements: oxygen, hydrogen, and nitrogen. Other elements, such as halogens and sulfur, round out the organic compound’s elemental core. Compounds with this set of atoms were the first to be applied with substitutive nomenclature. This nomenclature was so successful that it was extended to all elements in Groups 14, 15, 16, 17, and 13 to boron.

Fibers are elongated thick-walled cells with pointed ends and cellulose is present in its cell walls. It may or may not contain lignin. In the environment, apart from three natural sources(plant fiber, animal fiber, mineral fiber), fiber can be synthesized chemically from different kinds of materials and these types of fibers are named Synthetic fiber. Nylon, terylene, and rayon are different kinds of synthetic fibers. Other types of fibers include artificial silk or alginate yarn that are regenerated from carbohydrates and materials. There are also some fibers that are regenerated from the protein and bridal regenerated from groundnut protein.

What are the Types of Synthetic Fibre

There are different types of synthetic fibers, these are 

• Polyester 

• Acrylic 

• Rayon

• Nylon 

Polyester 

Polyester= Poly+ester

It is a category of polymer which contains an ester group in their main chain. The term polyester is used in specifying the material which is known as PET (Polyethylene terephthalate).

Properties of Polyester

• As Polyester is a category of polymer, it is very strong  

• Polyester is very resistant to shrinkage and it is very resistant to chemicals also.

• Polyester is very durable.

• As polyester is hydrophobic in nature, it gets dry quickly.

• As polyester is very strong, it retains its shape.

• It is easily washable.

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Uses

• Polyester suits are made from Polyester.

• It is used to make Industrial rope. 

• It is used to make pet bottles.

Acrylic

Acrylic is a synthetic fiber made from polyacrylonitrile named polymer. Character-wise, Acrylic fiber resembles wool. It is also known as  Polyacrylonitrile. This fabric is considered a fossil fuel based-fiber because it is produced by reacting to a variety of monomers with specific coal or petroleum-based chemicals. 

Properties of Acrylic 

• These types of synthetic fibers are flexible and soft.

• Acrylic fibers are warm and light.

• It is very much resistant to chemicals and moths or any other insects.

• Instead of wool, it is used because these types of synthetic fibers give a wool-like feel.

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Uses

• It is used in making a blanket, Shawls, Jacket, etc.

Rayon Synthetic

Rayon is an important synthetic fiber which is known as viscose-rayon regenerated cellulose. 

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Properties of Rayon 

• Rayon is a semi-synthetic fiber.

• This type of synthetic fiber is a versatile fiber.

• It can be dried easily. 

• These types of synthetic fibers do not insulate body heat. Thus, it is used in hot and humid climates.

• These types of fibers are soft enough and it is comfortable and highly absorbent.

Uses 

• It is mainly used for making fabric. 

• It is used for the preparation of surgical dressing and viscose-rayon absorbent wool. 

• Rayon is used in making cheap garments that have low prices. 

Nylon 

Nylon is an important type of Synthetic fibers. It is a polymer of adipic acid hexamethylenediamine. There is another synthetic fiber Terylene which is distinguished from nylon. These were terylene retains its structure on boiling with phosphoric acid. 

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Properties of Nylon

• It is a polyamide 

• These fibers are highly lustrous to dull, white, or colored. 

• It is soluble in hydrochloric acid and it is insoluble in acetone 

• It can be dried easily.

Uses 

• It is used for filter cloths. 

• These types of synthetic fibers are used for sieves. 

• It is used as non-absorbable sutures.

Difference between Natural Fibres and Synthetic Fibres

Learning the Types of Synthetic Fibres with Properties and Uses

There are several types of synthetic fibres that you must know about. By learning about the types of synthetic fibres with properties and uses, you can understand the difference between these fibres and natural fibres. Not only this, but it will also help you differentiate between synthetic fibres and other man-made fibres. In this topic, you will get to learn the properties of different types of synthetic fibres and how they are used for various purposes. If you want to start learning the concept of synthetic fibres, you can follow the tips mentioned below. 

• When you start learning about the types of synthetic fibres, you should have a clear understanding of what synthetic fibres are. 

• Learn the types of synthetic fibres along with their properties and uses that will help you differentiate between these fibres. 

• Not only synthetic fibres, but you should also learn about natural and other man-made fibres to understand the difference between all these different kinds of fabrics. 

• Use your textbook to read the detailed explanations and definitions of the types of synthetic fibres to get an idea of what these fibres are and how they are different from other fibres. 

• To learn more about the types of synthetic fibers with properties and uses, you can use ’s e-learning platform that provides you with the best study materials to help you study and secure an excellent score in the exams.

• Once you have completely understood the types of synthetic fibers with properties and uses, you should start practicing with questions given in your textbooks, reference books, previous year question papers, and sample papers to test your knowledge and check whether you need more preparation or not.   

Why is it Important to learn the Types of Synthetic Fibres with Properties and Uses?

Since synthetic fibers are an essential part of our life, it is important to learn about the different types of synthetic fibers with properties and uses. Not only synthetic fibers, but you should even learn the different kinds of natural and manmade fibres too. By learning the types of synthetic fibres with properties and uses, you can understand the importance of synthetic fibres in our lives. Below are some more reasons why you should learn types of synthetic fibres with properties and uses. 

• Since there are several types of synthetic fibres, having different properties and uses, it is better to know about each type to understand the difference between them. 

• Learning about synthetic fibers will not only enhance your knowledge of fibers but will also help you score well in the exam. 

• If you know about the types of synthetic fibers with properties and uses, you will be able to differentiate between natural and synthetic fibers. 

• Learning the types of synthetic fibers with properties and uses will also help you understand why these fibers are important and how they are used in our daily lives.

• With this topic, you can also explore the process of production of different types of synthetic fibers.   

WHAT IS NITRIC ACID?

Nitric acid is a highly corrosive mineral acid. It is also referred to as the spirit of nitre and aqua fortis. It is colorless. However old samples of nitric oxides may turn yellow due to the decomposition into oxides of nitrogen and water.

Fuming nitric acid is a solution containing more than 86% of nitric acid in water. The fuming nitric acid can be further divided into red fuming nitric acid (when the concentration is above 86%) and white fuming nitric acid ( when the concentration is more than 95%).

STRUCTURE OF NITRIC ACID

Nitric acid has a planar structure. Nitrogen is attached to three atoms of oxygen. Two of the nitrogen-oxygen bonds are equivalent and show resonance with double bond character.

This is the structure of nitric acid with its resonance forms.

USES OF NITRIC ACID

Nitric acid is an essential component of fertilizers.It is used to most in the production of fertilizers.It is neutralized with ammonia to give ammonia nitrate.

2. PRECURSOR TO ORGANIC NITROGEN COMPOUNDS

Nitration is carried out with the help of nitric acid for the addition of the nitro group. Most of the derivatives of aniline are prepared by the nitration of aromatic compounds which is then followed by reduction. Nitration includes combining nitric and sulphuric acid in order to form nitronium ion that reacts electrophilically with aromatic compounds like benzene.

3. NITRIC ACID AS AN OXIDANT

Cyclohexanone undergoes oxidation with nitric acid which is a precursor form adipic acid.

4. ROCKET PROPELLANT

Dilute nitric acid is used to determine metal traces in solutions. For such determinations, ultrapure trace metal grade acid is required because a small number of metal ions could affect the result of the analysis.
In electrochemistry, nitric acid is used in the purification processes of raw carbon nanotubes as well as a chemical doping agent for organic semiconductors.

6. WOODWORKING

Low concentrations of nitric acid(approximately 10%) are used to artificially age pine and maple to produce a grey-gold color which gives an old wax more oil finished wood look.

7.CLEANING AGENT

5–30% nitric acid and 15–40% phosphoric acid is commonly used for cleaning and dairy equipment to remove primarily calcium and magnesium compounds which are produced from the use of hard water during production or purification, or it could be deposited from the process stream.

The corrosive effects of nitric acid are used in pickling stainless steel as well as for cleaning silicon wafers in electronics.
Nitric acid is used with hydrochloric acid or alone to clean glass coverslips and glass slides for high-end microscopy applications. It is also used to clean glass before silvering while producing silver mirrors.

8. IN DAILY LIFE