Category: Chemistry Notes PPT

A mixture is defined as the combination of two or more substances that are combined physically. They can be separated by physical method. As there are no chemical changes involved, the components’ individual properties remain the same. In a mixture, every component has its own identity. During the formation of a mixture, there is no change in energy, and the Boiling point and the melting point of the mixture depend upon the characteristics of the constituents. Impure substances are also referred to as a mixture. Some example of the mixture includes:

1. Air: It is a mixture of various gases like oxygen, carbon dioxide, nitrogen, argon, neon, etc.

2. Seawater: It is a mixture of various salt and water.

3. Crude Oil: It is a mixture of Hydrocarbons.

Almost everything we see around is nothing but a mixture of one or more substances. Eg: The food we eat is a mixture of various ingredients, the air we breathe is a combination of gases and the fuel we use in vehicles is also a mixture of Hydrocarbons.

Mixtures can be broadly classified into two types: Homogeneous mixture and Heterogeneous mixture. 

In this topic, we will study the definition of homogeneous Mixtures, types of Homogeneous Mixtures, Let’s start with the definition of Homogeneous Mixtures.

What are Homogeneous Mixtures?

A homogeneous mixture is a type of mixture that has the same proportions of its components in a given amount of sample. Homogeneous mixtures can be solid, liquid, or gas. They have the same appearance and chemical composition throughout.

Examples of Homogeneous Mixtures include Water, Air, Steel, Detergent, Saltwater mixture, etc.

Alloys are formed when two or more metals are mixed together in some specific ratio. They usually are homogeneous mixtures. Example: Brass, bronze, steel, and sterling silver.

(If multiple phases exist in alloys, then they will be considered as heterogeneous mixtures) These are some different types of Homogeneous Mixtures present around us. As we have discussed What homogeneous mixtures are, Let’s understand the classification of mixtures.

Classification of homogeneous mixtures

Homogeneous mixtures can be Further Classified into:

1. Suspensions:

A suspension is a heterogeneous mixture of two or more substances. In it, the particles are suspended throughout the solution in bulk and can be seen easily by our naked eyes.  In this type of mixture, all the components are completely mixed and all the particles can be seen under a microscope and a mixture of particles has a diameter greater than 1000 nm. The particles do not pass through a filter paper. So a suspension can be separated by filtration. It scatters the beam of light passing through them because of its large particle size. The suspension is unstoppable and the particles settle down after some time. For example, Muddy water, A mixture of flour and water, Flour in water, Slaked lime for whitewashing, etc.

2. Solutions:

A solution can be defined as a homogeneous mixture of two or more components. The size of solute particles in the solutions is extremely small. It is less than 1 nm in diameter. Eg: When the salt dissolves in water,  sugar in water, soda water, etc. Solutions have two major components, one is solute and the other one is solvent. 

The component of a solution that dissolves the other component in itself is termed a solvent. In a solution, the solvent constitutes the larger component. For example, A solution containing sugar in water ( Solid in the liquid). Sugar acts as a solute and water is the solvent.

The component of the solution which is dissolved in the solvent is termed as solute. The solute is the smaller component in the given solution. Eg: In the above example sugar acts as a solute, In a solution of iodine in alcohol known as ‘tincture of iodine, iodine is the solute. Similarly, in cold drinks ( or soda water), carbon dioxide gas is the solute.

3. Colloids:

Colloidal solutions or Colloids are the mixtures in which microscopically dispersed insoluble particles of one substance are suspended in another substance, Not all the mixtures are colloids, The mixture where suspended particles don’t settle down at the bottom but get evenly dispersed into another substance. The size of the colloids ranges from 1nm to 1000 nm. Colloidal Solutions are divided into the following types: sol, emulsion, foam, aerosol, and gel.

Sol is a colloidal system in which the dispersed phase is solid, and the dispersion medium is liquid. Eg: Blood, Ink, Paint, Mud, etc.

An emulsion is a colloidal system in which the dispersed phase is liquid and the dispersion medium is another liquid. Eg: Milk, Salad dressing, Brewed coffee

Foam is a colloidal system in which the dispersed phase is gas, and the dispersion medium is solid or liquid. Eg: Whipped cream, Bubble bath, Fire retardant, etc.

An aerosol is a colloidal system in which the dispersed phase is a solid or a liquid particle, and the dispersion medium is a gas. Eg: Hairspray, Perfume, Mist, Fog, etc.

The gel is a colloidal system in which the dispersed phase is solid and the dispersion medium is liquid. Eg:  Toothpaste, Jam, Cheese, Rubber, Gelatin, etc.

Did You Know?

Tyndall effect is defined as the phenomenon in which the particles in a colloidal solution scatter the beams of light which are directed towards them. This effect is shown by all colloidal solutions and some suspensions. The Tyndall effect is used to check if the given solution is a colloid or not. The intensity of scattering of light is proportional to the density of the colloidal particles and the frequency of the incident light.

When a beam of light passes through a colloid, the colloidal particles present in the solution do not allow the beam of light to pass through them completely. The light particles collide with the colloidal particles and are scattered in different directions. This phenomenon of scattering makes the path of the light beam visible.

Wool is a textile fibre made from sheep and other species, such as goats’ cashmere and mohair, muskoxen’s qiviut, rabbit’s angora, and camelid’s various forms of wool. 

Wool fibre is a finely ordered structure with the cuticle, cortex, and medulla as its main histological components. Wool fibre is a natural fibre, and its characteristics such as diameter, crimps, and length are important parameters of the wool trait and indicators of the wool’s spinning quality.

What is Fleece?

If you are wondering What is Fleece? If there is such a thing as a man-made wonder commodity, fleece it is. While being named after a sheep’s fleece coat, it is made entirely of synthetic materials and is derived from plastic rather than a fluffy sheep’s coat.

Properties of Wool

1. Crimps: Wool fibre is wavy and twisted in some places. Crimp is the name for this waviness. The finer the yarn, the more crimps it will get.

2. Friction softens the wool fibre, particularly when wet, and is thus beneficial in maintaining a smooth, soft texture in fabrics. 

3. The heat has little impact at low temperatures, but high temperatures weaken the fibre and cause it to lose its colour. 

4. Moisture effect: Wool is the most hygroscopic material on the planet. It can absorb up to 50% of its weight and bear up to 20% of its weight without getting drenched.

5. When wool fibres are exposed to heat, moisture, and strain, they interlock and contract. Felting is aided by the scale-like exterior of the fibres.

6. Heat conductivity: Since wool fibre is a weak conductor of heat, fabrics made from it are best suited for winter wear. 

7. Wool is highly durable, and when hung after being wrinkled or formed, it returns to its original form. 

8. It has more strength than silk. Wool loses about 25% of its strength when wet. The yarn’s strength will increase as the fibre lengthens. 

9. Wool is a highly elastic material. When it’s dry, it’s about 10% to 30% stretched, and when it’s wet, it’s about 40% to 50% stretched. When it’s dry, it quickly returns to its original measurements. 

10. Wool has a high resistance to shrinkage. Long-term moisture exposure, on the other hand, can cause shrinkage.

Characteristics of Wool

1. Antistatic

2. Anti Wrinkle

3. Biodegradable 

4. Breathable 

5. Elastic

6. Fire resistant 

7. Nature’s fibre 

8. Odour resistant

9. Renewable

10. Stain-resistant 

11. Soft 

Processing Fibres Into Wool

1. Shearing – Shearing is the method of removing the woollen coat or fleece from an animal. Shearing instruments such as scissors, hand knives, and electric shears are used to do this without damaging the animal.

2. Scouring – Raw or grease wool is wool that has been taken directly from the sheep. To remove grease, dust, and dirt, raw sheared wool is washed in tanks with detergent and alkali.

3. Sorting and Grading – Defective or inferior wool is removed after scouring. Sorting is the term for this procedure. Grading is the method of sorting wool based on the weight, colour, and texture of the fibres.

4. Carding – Wool must be disentangled and washed until it can be used to make clothing. Continuous fibres are formed by separating the intermixed fibres.

5. Carded wool is twisted into a silver cord to make yarn. Silver is twisted and stretched into a thin thread. A mule spinning system is commonly used to spin woollen yarns. 

6. Washing and Finishing – Woollen yarn is spun or knitted into fabric, which is then used to produce finished goods like clothing, tablecloths, and bags.

Types of Wool Fabric

Here mentioned are the types of wool fibres-

1. Lambswool is derived from the first shearing of a young sheep (lamb) at about seven months of age. It’s also known as virgin wool, but that term also applies to wool that hasn’t been processed yet. Shearing the lamb at this point produces wool that is exceptionally smooth, fluffy, and fine, as well as hypoallergenic.

2. Merino wool is derived from the merino sheep breed, which originated in Spain, though most merino wool is now exported from Australia. Merino wool is known for its fine fibres, which give it a supremely soft hand and make it ideal for garments that come into direct contact with the wearer’s skin, such as base layers.

3. This wool is produced by Shetland sheep from Scotland’s Shetland Islands. It’s thicker and coarser than other wools, such as merino, due to the region’s cold climate.

4. Mohair is a type of wool that comes from the Angora goat and differs from other types of wool for many reasons. In the shearing process, guard hairs from the goat’s topcoat are often mixed in with the undercoat. Angora goats are grown in a mild environment, so their fibres aren’t as coarse as other wools; their longer length gives the fibre its smoothness and results in a uniquely fluffy cloth.

5. When cashmere (Kashmir) goats join the moulting season, they have their undercoats shorn. Since cashmere is shorn from the undercoat, the yield per goat is low, so a single sweater needs two cashmere goats.

6. Angora wool is the lightest, best, and warmest
   of the natural fibres, coming from Angora rabbits. Angora fibres are hollow and smooth, similar to alpaca fibres, giving them unrivalled warmth and loft. The fibres are incredibly fine, but they are also extremely fragile. As a result, angora is often blended with other fibres to improve its longevity.

7. The majority of camel hair comes from Bactrian camels, which are born in cold climates such as Mongolia, China, and Russia, and is collected in the spring when the camel moults. Camel hair has a hollow appearance similar to mohair and is smoother and longer than sheep’s fur. As a result, the fabric is lighter and lustrous than sheep’s fur, and it’s just as soft as cashmere.

8. The undercoat of the arctic muskox, which is bred in Canada and Alaska, is used to make Qiviut fur. The undercoat of the muskox is shed during the moulting season, and breeders either harvest the wool by combing it or plucking it from the grass. Qiviut is eight times colder than superfine sheep’s wool and is finer than superfine sheep’s wool. It also does not shrink when submerged in water.

Did You Know?

Alpacas are South American animals that grow hollow fur. Alpaca has a peculiar property that makes them both lightweight and insulating. It’s both lighter and warmer than wool from sheep. Alpaca is comparable to cashmere in terms of softness, but it is much heavier. Alpaca hair is hypoallergenic by nature, making it perfect for those who have sensitive skin.

Zinc nitrate is an inorganic chemical compound that is a colorless crystalline solid with the chemical formula Zn(NO3)2. It is non-combustible but accelerates the burning of combustible materials.  This white, crystalline salt is highly deliquescent (Deliquescent: Certain substances have the property to absorb moisture when exposed to the atmosphere at ordinary temperature, they initially become wet, lose their crystalline form and finally dissolve in water to form a saturated solution) in nature. Zinc nitrate solution is soluble in both water and alcohol. Nitrate compounds are mostly soluble in water. Nitrate materials are also good oxidizing agents. When they are mixed with hydrocarbons, these compounds can form a flammable mixture. Let’s discuss the Properties of Zinc nitrate, Zinc nitrate structure, and its uses.

 

Production of Zinc nitrate

Zinc nitrate is produced by dissolving zinc in a nitric acid solution. Below is the reaction with dilute and concentrated Nitric acid.

Zn + 2 HNO3 (diluted)  → Zn(NO3)2 + H2

4 Zn + 10 HNO3 (concentrated)  →  4 Zn(NO3)2 + NH4NO3 + 3H2O

 

After thermal decomposition of Zinc nitrate, it forms zinc oxide, oxygen, and nitrogen dioxide.

2 Zn(NO3)2 + Heat → 2ZnO + 4 NO2 + O2

 

Properties of Zinc nitrate

 

Zinc Nitrate Structure

()

 

Uses of Zinc Nitrate

• Zinc Nitrate is used as a catalyst in the manufacture of many chemicals, in the manufacturing of medicines, and dyes as a mordant.

• It is used as a strong oxidizing agent.

• It is used in liquid fertilizers.

• It is also used as a latex coagulant.

 

Did You Know?

• Zinc is a valuable catalytic agent in hydroxylation and other enzymatic reactions since it is an effective Lewis acid. The metal also has a versatile coordination geometry, allowing proteins to change conformations quickly to conduct biological reactions. Carbonic anhydrase and carboxypeptidase are two zinc-containing enzymes that are important for the regulation of carbon dioxide (CO2) and the digestion of proteins, respectively

• Carbonic anhydrase converts CO2 into bicarbonate in vertebrate blood, and the same enzyme then converts bicarbonate back to CO2 for exhalation through the lungs. This conversion would take a million times longer without this enzyme at a standard blood pH of 7 or would require a pH of 10 or higher. Plants need the non-related -carbonic anhydrase for leaf formation, indole acetic acid (auxin) synthesis, and alcoholic fermentation.

• Zinc is a trace element that is needed by humans, other mammals, plants, and microorganisms. Zinc is stored and transferred in metallothioneins, which are necessary for the function of over 300 enzymes and 1000 transcription factors. After iron, it is the second most common trace metal in humans, and it is the only metal found in all enzyme groups.

There is quite a relation between pressure and volume and is provided by a formula. This formula was given by Robert Boyle in 1660. He is also rightly known as the Father of Modern Chemistry who has worked both in the fields of chemistry and physics. A book named The Spring and Weight of the Air is the one in which he had mentioned the various experiments that he had conducted using a vacuum pump and has also mentioned this relation between volume and pressure which is also called Boyle’s law.

Boyle’s Law Formula

According to this experimental gas law, the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature. An important point to note here is that the amount of ideal gas (i.e., number of moles) is kept fixed and a constant temperature is maintained. Under this condition, the pressure of the gas will tend to increase if we decrease the volume of the container and vice-versa.

 

Mathematically, it can be expressed as:

()

Where ‘P’ is the pressure exerted by the gas and ‘V’ is the Volume of the container.

Graphically, we can observe the behaviour of the curve as follows:

()

You can see how the value of Pressure decreases when the Volume is increased or vice-versa.

In order to understand it better, let us go through a simple example:

Example: If 20[c{m^3}] gas at 1 atm. is expanded to 50 [c{m^3}] at constant T, then what is the final pressure

Options:

(a) [20 times frac{1}{{50}}]

(b) [50 times frac{1}{{20}}]

(c) [1 times frac{1}{{20}} times 50]

(d) None of these

Answer: (a)

Solution:

At constant [T,{P_1}{V_1} = {P_2}{V_2}]

[1 times 20 = {P_2} times 50]; [{P_2} = frac{{20}}{{50}} times 1]

We hope you have understood, how to apply the Boyle’s Law Formula. Now in order to test your understanding, try and solve the Question by yourself.

Example: An ideal gas exerts a pressure of 3atm in a 3L container. The container is at a temperature of 298K. What will be the final pressure if the volume of the container changes to 2L?

Options:

(a) 2 atm

(b) 3.5 atm

(c) 4.5 atm

(d) 4 atm

Answer: (c)

Solution:

Boyle’s law can be written as follows:

[{P_1}{V_1} = {P_2}{V_2}]

Use the given volumes and the initial pressure to solve for the final pressure.

(3atm)(3L)=(2L)P2

P2=4.5atm

What is Molar Mass?

The mass contained in one mole of a substance is called molar mass. It can also be defined as the amount of substance in grams present in one mole of the substance. In one mole 6.023 × 1023 molecules are present. This number is called Avogadro’s number. Molar mass is the most important term used in physical chemistry. In this article, we will cover the molar mass, molar mass formula, molecular mass and its formula, the difference between the molar and molecular mass, and relative molar mass and its formula.

Difference Between Molar Mass and Molecular Mass

What is Relative Molecular Mass?

The relative molecular mass of a substance is the sum of the atomic masses of all the atoms in a molecule of the substance. It is measured in terms of u (unified mass).

Molar Mass Formula and Molecular Mass Formula 

Molecular Mass

Molecular mass (AB2) = atomic mass of A + 2 × atomic mass of B 

Molar Mass

Molar mass (AB2) = atomic mass (in grams) of A + 2 × atomic mass of B (in grams)

Solved Examples 

Example: Find the molecular of the water molecule.

Solution: The formula of the water molecule is H₂O.

The atomic mass of hydrogen = 1 amu

The atomic mass of oxygen = 16 amu

Molar mass of water = 2 *1 + 16 = 18 amu.

Example: What will be the relative molar mass of the hydrogen molecule.

Solution: Hydrogen molecule represented by H₂.

The relative molecular mass of hydrogen molecule = sum of the relative atomic masses of two atoms of hydrogen.

⇒ 1U + 1U = 2U.

Conclusion

Molar mass, molecular mass and relative molar mass are differ from each other in terms of the unit they express. Molar mass represents the weight of one mole molecule in g/mol, molecular mass represents the weight of one molecule in amu and relative molar mass represents the weight of a single atom in terms of ununified mass. 

Magnesium Nitride is more commonly referred to as trimagnesium dinitride. It is an inorganic compound and has two atoms of nitrogen and three atoms of magnesium.

Chemical Formula

The chemical formula of magnesium nitride is Mg₃N₂. It has an anion valency of (3-). Therefore, it is also known as trimagnesium nitrogen(3-).

Structure

The structure of magnesium nitride consists of three cations of magnesium which can be denoted as Mg²⁺ and two anions of Nitrogen (III) which can be denoted as N^3-.

Magnesium nitride is found in nature in the form of the mineral nitromagnesite.

Properties

Physical Properties

Magnesium nitride is greenish yellow in color and exists as a powder in room temperature and normal pressure. It has a molar mass of 100.95 g/mol and has a density of 2.712 g/cm³. It can dissolve in  acid and water as well but is slightly soluble in ether and ethanol. The melting point of magnesium nitride is 1500°C and when heated beyond this temperature, it results in decomposition of the powder and forming of a gas of nitrogen.

Chemical Properties

Magnesium nitride is a hard compound and is actually ceramic in nature. Magnesium nitride has high thermal conductivity. It has high corrosion resistance which makes it very useful in the production of other nitride compounds. It also had high wear resistance and temperature resistance. Magnesium nitride is used as a catalyst in the synthesis of borazon.

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