Category: Science

Introduction

Alcohols and phenols are formed by replacing one old hydrogen atom in the hydrocarbon. In the case of alcohols, the -OH is known as the hydroxyl group, while it is called the phenolic group. It is attached to a benzene ring. Since they have a common functional group, most of the characteristics of alcohols and phenols are expected to be the same. However, they do differ in many properties. It is primarily due to the reason that the phenolic group is involved in residence or conjugation with the benzene ring. While no search resonance is possible in alcohols. This makes phenols considerably acidic while alcohols hardly exhibit any acidic in nature. Members of both these families have analytical and industrial importance.

Structure of Alcohol

Alcohols which contain one -OH group that is monohydric compounds are also known as alcohols. These are represented by the formula R-OH These are additionally categorised as primary (1°), secondary (2°) and tertiary (3°) varying on the behaviour of the carbon atoms to which the -OH  group is bonded. For example,

Structure of Phenol

Phenols are aromatic compounds that contain one or more, -OH groups called phenolic groups that are attached directly to the ring. Phenols may be further classified as monohydric, dihydric, trihydric, etc, depending upon the number of -OH, groups bonded to the ring.

Monohydric phenols known as the parent or simplest member of the family with one -OH group attached to the ring are called phenol.

In dihydric phenolic compounds 2 -OH, groups are attached directly to the ring.

Trihydric phenols compounds are known in which 3 -OH groups are directly attached to the ring

Difference Between Hydroxyl and Alcohol

What is Hydroxyl?

The term hydroxyl is used to refer to the -OH radical. A functional group found in both organic and inorganic compounds is the hydroxyl group. The chemical formula for this compound is -OH. As a result, the hydroxyl group is made up of one hydrogen and one oxygen atom. The hydroxyl radical is extremely reactive and can initiate chemical reactions almost instantly. The Hydroxyl radical is the Hydroxide ion’s neutral form OH–. This hydroxyl radical has an unpaired electron, which results in the radical’s high reactivity.

What is the Relationship Between Hydroxyl and Alcohol?

Alcohols are composed of the  -OH  groups. These -OH groups behave as the functional group of alcohols. Consequently, the -OH group affects the physical and chemical properties of alcohols.

Because of -OH group presence alcohols tend to show some properties that are only because of the -OH group.

1. They are polar compounds directly because of the presence of -OH groups.
2. Alcohols are soluble in polar solvents.
3. Alcohols have the ability to form Hydrogen bonds.
4. Alcohols are soluble in water.
5. Alcohols tend to have higher boiling points than the equivalent alkanes because of the existence of these hydrogen bonds.

Summary

Alcohols and phenols are formed by replacing one or more hydrogen atoms in hydrocarbons by -OH groups. In the case of alcohols, the -OH group is known as the hydroxyl group, while it is called the Phenolic group when connected to a benzene ring. Given that they have the same functional group, most of the properties of alcohols and phenols are believed to be similar. Nevertheless, they do not differ in many properties, it is mainly because of the explanation that the phenolic group is engaged in resonance or conjugation with the benzene ring. However, no such resonance is feasible in alcohols. This makes phenols significantly acidic, while alcohols barely demonstrate any acidic character. Members of both these families have analytical and industrial significance. Ethyl alcohol, commonly called alcohol, is a starting material for the manufacture of ether, chloroform, acetic acid, etc. It can also be used as a fuel for spirit lamps and stoves due to its highly combustible nature. But it’s important, is in its ability to act as a beverage in the form of beer, wine, whisky, Brandy, etc. phenol finds application in the synthesis of Bakelite, plastics, drugs, etc.

Frequently Asked Questions

1. Out of Phenols and Alcohols, which one is more acidic in nature and why?

Phenols are more acidic in nature because of the explanation that the phenolic group is engaged in resonance or conjugation with the benzene ring. However, no such resonance is feasible in alcohols. This makes phenols significantly acidic, while alcohols barely demonstrate any acidic character.

2. Name the tests to distinguish between primary, secondary and tertiary  

    Alcohol?

In the chemical properties of alcohols, we have seen that the three types of alcohols differ in the nature of their products. However, they cannot be distinguished practically based on these characteristics. Special tests are employed for this purpose. These are described as follows.

Victor Meyer’s Test (Red-blue Colourless Test)

1. In this, a blood-red colouration indicates primary alcohol.
2. A blue colouration indicates secondary alcohol
3. A colourless solution represents tertiary alcohol

Lucas Reagent Test

1. If turbidity appears immediately, alcohol is tertiary
2. If turbidity appears after some time, alcohol is secondary
3. In case turbidity appears on heating, alcohol is primary

3. Describe Lucas Reagent test? Why is it important? What are its limitations?

This test is based on the reactivities of primary secondary and tertiary alcohols with Hydrochloric acid. The given alcohols are treated with Lucas reagent, which is an equal mixture of concentrated HCl and anhydrous \(ZnC{l_2}\), which is a dehydrating agent. The product is alkyl chloride or chloroalkane accompanied by white, turbidity or cloudiness.

The time taken for the appearance of turbidity is different in the 3 types of alcohols and affords a method for their distinction.

1. If the turbidity appears immediately, alcohol is tertiary
2. If the turbidity appears after sometime, alcohol is secondary
3. In case the turbidity appears on heating, alcohol is primary

Limitations of Lucas reagent.

Lucas reagent test is not applicable to the alcohols with 6 or more carbon atoms. As they are not water soluble, no reaction with Lucas reagent is possible.

4. Describe the physical properties of Phenols?

• State and smell. Phenols are either colourless crystalline solids or liquids. However, when exposed to the atmosphere, they become reddish or pinkish due to the formation of oxidation products. Phenols have a characteristic smell, known as phenolic smell. 
• Solubility. I like alcohol. Phenols are only sparingly soluble in water. They are also expected to form hydrogen bonding with water molecules due to the polar nature of the -OH group present. 
• Boiling points. Phenols are expected to have higher boiling points than expected from their molecule formula, mainly because of the polar nature of the -OH group. Thus, these are having higher boiling points than the aromatic hydrocarbons of comparable molecular masses. 

5. What will happen when alcohol is oxidised?

Oxidation of primary alcohols to aldehyde

Aldehydes are the oxidation products of primary alcohols.

Oxidation of secondary alcohols to Ketones

Ketones are products of oxidation of secondary alcohols.

Introduction

Astrophysics is a field of study focused on celestial objects such as the sun, comets, stars, asteroids, meteoroids, and galaxies. It aims to understand the birth, life, and death of stars. Asteroids are small objects orbiting the sun and most of them are floating in the portions of our solar system that lie between Mars and Jupiter. 

On the other hand, comets are made up of various elements covered with easily vaporizable substances like water, methane, and ammonia. Comets also orbit the sun in elliptical orbits which lie far away from the sun. As they approach closer to the sun, the materials on their surface vaporize and form a “tail” of sorts, which can be as long as 10,000 km. We also have meteoroids, which are partially burnt pieces of asteroids that fall down to Earth. 

What is Asteroid? 

Asteroids are small celestial bodies that orbit around the Sun and are typically found between Jupiter and Mars in what is known as the asteroid belt. Scientists estimate that this belt contains around 700,000 known asteroids of which only 1,600 orbit the Sun. Note that these are only the known asteroids and there might be several hundred thousand others as well. The asteroid Ceres, with a radius of about 700 km, is the largest asteroid in the belt and takes about four and a half years to orbit the Sun. Although asteroids exert a gravitational pull due to their large size, they lack an atmosphere. Their orbits can be influenced by the gravity of Jupiter or when they get close encounters with Mars. This can sometimes cause them to move out of the asteroid belt and into the orbits of other planets. The International Astronomical Union’s Committee on Small Body Nomenclature assigns names to asteroids.

An asteroid

Classification of Asteroids 

Asteroids have been classified into three groups based on their location in our solar system. Further, the composition of the asteroid may also be used as a criteria to classify the asteroids. For instance, C-type asteroids, which are the oldest ones known, are formed of silicate rock and clay and have a very dark appearance. They are also the most common ones. M-type asteroids are metallic and contain combinations of nickel and iron. Finally, S-type asteroids are formed of nickel-iron and silicate materials.

Types of Asteroid

Based on the location of the asteroids, we have: 

Main Asteroid Belt: An asteroid belt is a group of asteroids and there is one such belt in our solar system between Mars and Jupiter. 

Trojans: Sometimes, asteroids in the main belt can lose their orbit and get into orbit with another planet. They are known as Trojans and their orbits are characterised by two special points known as Lagrangian points.

Near-Earth Asteroids: These are asteroids whose orbits lie close to Earth’s orbit. Some of them can even cross the orbit and are then termed as earth-crossers.

Characteristics of Asteroids 

• Asteroids have no specific shape. They may be thought of as randomly shaped bodies with holes on the surface.
• They revolve around the sun in their orbits but their own revolution has no specific direction.
• Some asteroids may have one or even two small companion moons.

What is Meteoroid?

When a comet approaches the sun closely, it disintegrates into smaller fragments. While passing through Earth’s orbit, these fragments can get pulled into our gravitational pull and fall down. Before they enter the atmosphere, they are referred to as meteoroids. However, due to friction with the Earth’s atmosphere, most of these fragments burn up, causing what we know as meteor showers. In this stage, they are known as meteors. Sometimes, though, the fragments are large enough to survive the atmosphere and small pieces that remain after burning up fall down as meteorites.

 A meteorite

Composition of Meteoroid

Meteoroids are composed of silicates, oxygen, and a few heavy metals like iron and nickel. Meteoroids can get broken up into smaller fragments due to collision with other objects but generally, the composition remains the same.

Characteristics of Meteoroid

• Meteoroids generally are more dense than Earth’s rocks, owing to the iron and nickel content in them.
• There is a unique thumbprint-like shape of pits on most meteoroids, but they don’t have holes.
• They have random shapes and sizes.

Difference Between meteoroid, meteor, and comet

Summary

Asteroids are celestial objects that orbit the sun in a belt that is located between Mars and Jupiter. This belt consists of millions of asteroids. On the other hand, comets are composed of small, solid particles and covered with substances such as water, methane, and ammonia. When a comet breaks apart and falls on Earth, it’s called a meteoroid. The surfaces of celestial objects like the moon, Mercury, and Mars have craters because of meteoroid impacts. Meteoroids can also be formed by the collision of two asteroids.

 

Frequently Asked Questions

1. What are the types of Stars?

There are many types of stars, some of which are:

1. Double and multiple stars
2. Intrinsically variable stars 
3. Nova and super Nova

2. What is albedo?

The portion of the solar energy that is reflected by a planet is referred to as albedo, and it can help us understand the atmosphere of planets. For instance, Venus has an albedo of 0.85, which means a denser and heavier atmosphere compared to other planets. On the other hand, Mercury has an albedo of 0.06, which corresponds to no atmosphere,

3. Explain Halley’s Comet.

Since comets travel in orbits, some of them are visible from Earth at regular intervals. Halley’s comet has a period of 75-76 years and the last time we saw it was in 1986 and before that, in 1910. This is the only periodic comet that is visible from the Earth with a naked eye.

4. What are the conditions for life on any planet?

• The thermal conditions, i.e., the temperature must be in the survivable range.
• The atmosphere must support life.
• The amount of water on the planet must be considerable.

5. What are White Dwarfs? 

White dwarfs are small stars that do not possess the capability for nuclear fusion and consist of elements that are lighter than iron.

Introduction

When an electric current flows through a straight copper wire, it generates a magnetic field that forms circular patterns around the wire. The Biot-Savart law is a relation that allows us to calculate the strength of this magnetic field at different distances from the wire. And its applications aren’t limited to straight wires. For instance, when current flows through a circular loop of wire, a magnetic field forms along the axis of the loop and by analyzing small segments of the wire, we can again use Biot-Savart law to understand this magnetic field. Thus, the Biot-Savart law helps us derive magnetic fields due to current-carrying conductors.

 Magnetic field due to wire

What is Biot-Savart Law?

A rod with an electrical coil carrying current wound around it can act as a magnet. Similarly, when current passes through a straight electrical wire, it creates a magnetic field. Although the measurement methods for an electrical coil and straight electrical wire differ slightly, the principle remains the same – magnetic fields originate around a conductor carrying an electric current. Through experiments with electric current and conducting wires of various shapes, the properties and characteristics of magnetic fields were understood, leading to the development of the Biot-Savart Law. Further, the direction of the magnetic field can be arrived at using the following two rules:

• The right-hand rule 
• The right-hand thumb rule

The first of these rules is related to the force experienced by charged particles in a magnetic field while the latter is related to Biot-Savart law. The latter being our focus, we state it here. According to the right hand thumb rule, if we point our thumb along the direction of current flow, our fingers curl around in the direction of the magnetic field.

Derivation of Biot-Savart Law

According to the Biot-Savart law, the magnetic field created by an infitesimal current element dl carrying a current I at a point P is:

• Directly proportional to the current and the length of the element (I dl).
• Directly proportional to the sine of angle made by the direction of current and the length of the element.
• Inversely proportional to the square of the distance from the element to the point in question.

Biot-Savart law

Biot-Savart Law Formula

A general formula that can be derived via the Biot-Savart law is that of a magnetic field created by a coil of N turns along its axis. It is given as:

Here,

N = Number of turns in the coil

I = Current flowing through the coil

R = Radius of the coil

z = Distance along the axis to the point where the magnetic field is being calculated.

At the centre of the coil, z=0 and the formula becomes:

Applications of Biot-Savart’s Law

Since Biot-Savart law can estimate magnetic fields, it can be used to estimate the sag that high tension lines would undergo and prevent them from snapping.

Biot-Savart law also enables us to determine the strength of the magnetic field at the centre of a current loop or at any point on its axis, as well as at a distance from a straight current-carrying wire. These scenarios are depicted in the figure above. Further, we can apply this law in aerodynamics theory to calculate and understand the characteristics of a vortex produced by high-velocity air pressure, which is shown in the figure below. Finally, we can employ it to model the atomic responses inside magnetic fields.

 Vortex of air

Importance of Biot-Savart’s Law

The various applications of this law have already been demonstrated. Thus, it comes in of immense use in almost all fields of physics and engineering. Here are a few examples:

Example: What is the magnetic field at the centre “O” in the figure shown below?

Since the current on either portion of the circle is in the same directions, the magnetic fields point in the opposite direction (use right hand thumb rule). Thus, they cancel out and we have

Summary

Biot-Savart law is a fundamental law in magnetostatics that explains the relationship between currents and magnetic fields. It is applicable in the case of static currents and plays a significant role in calculating the velocity of vortex lines in aerodynamics. This law is consistent with Gauss’ and Ampere’s laws and its applications include determining the field due to current on a conductor or a current-carrying loop.

 

Frequently Asked Questions

1. What is the other name of Biot-Savart law?

The Biot-Savart law is also known as Laplace’s law. 

2. What is the value of relative permeability in the air? 

Air has a relative permeability of 1.

3. Describe Helmholtz coils and their application.

Helmholtz coils are two identical coils placed a certain distance apart with their axes coinciding. When current flows through them, a region of almost uniform magnetic field is obtained between them.

4. What is the unit of permeability as a unit of force?

In units of force, the unit of permeability is \(N{A^{ – 2}}\).

5. What is the flux density at the center of a solenoid coil with lengths L and N turns?

At the centre of a solenoid, magnetic flux density is given as \(\overrightarrow B  = \frac{{{\mu _0}NI}}{L}\).

Introduction

A battery is an electronic device that converts chemical energy to electrical energy through a redox reaction. They are typically composed of a combination of cells, with cells being the fundamental unit of batteries. Energy is stored in these cells and drawn as current and thus, the output of any battery depends on the combination of cells used inside it. 

There are two terminals on batteries, of which, one end is known as the cathode and the other end as the anode. Upon connecting a circuit to the battery, electrons can move from one node to the other and thus, current can flow through the circuit. In electrical circuits, batteries and cells can be connected in various combinations such as series, parallel, and even mixed. Today, various types of batteries are available in the market, including Pb-acid batteries, Li-ion batteries, Ni-Cd batteries, etc.

Important terms related to battery

EMF of battery: When no external factors and voltage sources are present, the potential difference between the two terminals of the battery is known as its emf, short for electromotive force.

Terminal voltage: When current starts flowing in the circuit, the potential difference between the battery’s terminals is termed as terminal voltage. Note that since the battery is an electrical device, resistance to current flow is natural. The resistance offered by the battery itself is known as internal resistance, and it creates a voltage drop across its terminals.

Let V be this voltage drop and E be the emf of the battery. Then,

Internal voltage drop= E-V

Internal resistance: As mentioned, the battery has an inherent resistance inside it, which is known as internal resistance.

Batteries in series and parallel

Series combination

This is like creating a train of batteries. The positive terminal of each battery is connected to the negative terminal of the next one and in this arrangement, the same amount of current flows through each of them. Hence, the voltages offered by the batteries can be added algebraically to get:

Parallel combination

In this combination, the positive terminals of all the batteries are connected to each other and the same is done for all the negative ones. In this configuration, the voltages dropped across the terminals remain the same and we can add current algebraically.

Connecting batteries in series

Series combination is used when we need to increase the voltage without changing the amount of current. Here is an example:

Say we had a battery of EMF 20 V and capacity 100 A-h. Then, if we connect them in series as shown below, we would end up with a combination that yielded us 40 V output but with no change in capacity.

Series combination

Hence, we get an output with increased voltage. Note that the capacities of the batteries must be the same or they might get damaged.

Advantages of Series Combination

1. Since the current flow does not increase, there is no additional heat generated.
2. It is simpler than parallel combinations.
3. The voltage drop increases.

Disadvantages of Series Combination

1. Any break or damage in the circuit at any point will damage the circuit.
2. Increased number of components also increases the resistance of the circuit.
3. A low voltage system is not compatible with this combination.

Batteries in Parallel

If we wish to increase the capacities of batteries without changing the output voltage, we use a parallel configuration. This increases the current flow in the circuit. For instance, given two batteries of 24 V, 100 A-h each, connecting them in parallel would give us a battery that provides 200 A-h at 24 V.

Parallel Combination

This sort of combination is used in solar panels.

Advantages of Parallel Combination

1. The capacity increases, yielding to increase in use-time,
2. The voltage remains the same.

Disadvantages of Parallel Combination

1. The current is increased, causing heat to increase.
2. Charging batteries in this configuration takes longer.

Mixed Combination

As implied by the name, mixed combination is the combination of some batteries connected in series linked together in parallel combination or vice versa. This is a complex arrangement that can help us generate almost any combination we want from a given bunch of batteries.

For example, suppose we were given six batteries of 15 V and 100 A-h each. We could combine them as follows:

1. Set 1 – B1 and B2 linked in series = 15V + 15V = 30V, 100 amp hour
2. Set 2 – B3 and B4 linked in series = 15V +15V = 30V, 100 amp hour
3. Set 3 – B5 and B6 linked in series = 15V + 15V = 30V, 100 amp hour

Next, we would combine the above sets in parallel, giving us a 30 V, 300 A-h configuration, visible in the diagram below.

Mixed combination

Hence, the effective voltage drop will remain at 30 V, but the capacity would be three-folds.

Summary

Depending on our requirements and the scenario in question, different combinations of batteries can be used. The most commonly used ones are series, parallel, and mixed grouping of batteries. What we use is entirely up to us and depends on the requirements of the circuit. The output of the configuration depends on its design and thus, if we needed higher voltage, we would opt for series combination and if needed higher capacity, we would use parallel configuration. Similarly, mixed grouping allows us to generate arbitrary configurations from a given set of batteries.

Frequently Asked Questions

1. Can we put a 12V 100 amp hour battery and a 15V 200 amp hour battery in a series combination?

No, since they have different capacities. For series combination, the capacities of the batteries must be the same.

2. How does a battery work?

A battery is composed of electrochemical cells, which convert chemical energy into electrical energy. When connected to a circuit, ions flow inside, leading to the flow of current.

3. Name the reaction that takes place in the batteries

The process is known as redox reaction and it involves reduction and oxidation simultaneously.

4. How are batteries classified?

Batteries may be classified as follows:

1. Primary batteries: These are one-time batteries which can not be recharged after they get depleted.
2. Secondary batteries: These batteries can be recharged after use, giving them longer life. 

5. What type of electrical combination is used for domestic purposes and why?

In domestic applications, parallel combination is used since it supplies an equal amount of voltage to all the devices, which is necessary for proper functioning.

Introduction

Protein, DNA, and RNA can all be separated from one another using an external electric field and this laboratory technique. As the gel or matrix employed includes a given size and enables just a particular molecule, the separation of molecules occurs on the basis of charge and size. Only very small particles, such as atoms or ions, may fit through the pores. By doing so, molecular separation is possible.

When electricity flows, ions can migrate to various poles. In electrophoresis, the movement of anions is known as anaphoresis and that of cations is known as cataphoresis. When a current is applied, proteins migrate to the positive poles, where they may be more easily separated.

What is Electrophoresis?

Electrophoresis is the process by which a current drives charged molecules to separate poles. Molecules with a positive charge will go away from the cathode and towards the anode. Negatively charged molecules will seek out a cathode, which is the opposite pole of an electrode.

As proteins and nucleic acids are negatively charged, they gravitate towards the cathode. Because to its association with electricity and ion motion, electro kinetics is another name for this field. Capillary electrophoresis and slab electrophoresis are the two most common forms. Gel and paper electrophoresis are examples of capillary electrophoresis, while Iso-electro focusing and Zone electrophoresis are examples of slab electrophoresis.

Gel Electrophoresis

Applications of Electrophoresis

Electrophoresis is applied in many fields because of its feasibility and inexpensive mode. Some of its applications are,

DNA Fragmentation and DNA Analysis 

Gel electrophoresis is the process used for the separation of DNA fragments based on their size. The approximate size of DNA is also obtained in this process

Protein Detection

Gel electrophoresis is again employed for the detection of proteins. Proteins have higher migratory power and that is employed for its detection. By the application of external current, the charged particles of proteins will migrate towards their opposite electrodes. As protein is negatively charged it will migrate towards the cathode. It can also use the liquid matrix for the separation. The majority of protein applications can be achieved by the use of this process. They include purity determination and purification of proteins.

Testing of Antibodies

Immune electrophoresis detects antibodies. Antibodies on a gel do it. blood test. If the sample contains the antigen, an antigen-antibody complex will form. IgA, IgM, etc. are easily diagnosed.

Factors affecting the Process of Electrophoresis

Some factors can substantially affect the process of electrophoresis. They are,

Electric Field: Electric field is responsible for the movement of charged particles towards the oppositely charged electrodes. So it plays an important role in the process of electrophoresis.

 Sample features/details: The features of the sample such as size, shape, and charge have an important role since it is a size-based and charge-based separation. If the charge of a molecule is high the rate of migration will also high. But if the size increases the rate will decrease.

Buffer: For stabilizing the pH of the medium buffer solution is necessary the use of zwitterionic buffers will be much better.

Supporting Medium: It plays a predominant role since the medium can alter the rate of migration by having some adsorption property. Electro osmosis will also result due to some mediums. So selection of a proper support medium will increase the rate of migration.

 How does gel electrophoresis work?

Gel electrophoresis is a type of electrophoresis in which charged particles or ions of biological molecules can be separated by the application of an external field. They move through a gel hence the name gel electrophoresis is used. And its movement is called migration. And the migration of ions is to oppositely charged electrodes. The electric current for this process is applied across the gel. The gel acts as a sieve since it contains small pores that can only allow small-sized molecules. DNA fragments are distinguished using this electrophoresis. And DNA is a negatively charged species so it will migrate to the rds cathode.

What is agarose gel electrophoresis?

One of agar’s main components is a matrix for the electric current-based synthesis of macromolecules. Agarose gel is commonly employed as a matrix in the separation of DNA and big protein molecules because it is simple to cast, has a good pore size, and has a good gel strength. It has several charged groups and aids in water movement in the opposite direction of DNA movement towards the anode. A larger concentration of agarose gel is required for the separation of tiny molecules.

What are the advantages of electrophoresis?

The advantages of electrophoresis are,

• The mode of operation of this technique is easy.
• Short time is only needed.
• Needs only a low sample.
• The consumption of electrolytes during the process is low.
• Can be used as an analytical tool and also as a synthesis tool.
• The bulk amount of proteins shall be separated.
• Inexpensive apparatus.

Summary

Samples are separated by size and charge using electrophoresis. It is medium dependent, and the various forms it takes are defined by the medium used. Several types of electrophoresis in tubes and capillaries. Gel electrophoresis, zone electrophoresis, etc., are also included. Gel electrophoresis stands out because it is used to separate proteins, DNA, RNA, and other biomolecules. Gels aid the separation process since only molecules of a certain size may pass through them; if an electric field is applied, the molecules in question will align themselves into a distinct band, making them easy to identify. The supercoiled structure of agarose gel makes it a viable alternative matrix. Electrophoresis has various benefits due to being a cheap and efficient method.

 Frequently Asked Questions

1. What is the difference between SDS-PAGE and Native PAGE?

Ans. SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) is a technique used to separate proteins based on their size and charge. Native PAGE (polyacrylamide gel electrophoresis) is a technique used to separate proteins based on their size and shape. 

2. What is Capillary Electrophoretic Enzyme Assay?

Ans. Applications of the analytical separative technique known as capillary electrophoresis (CE) extend far beyond the realm of enzymatic research.

In an open capillary, the substrate and the product are separated by size and charge in an electric field.

3. What is the haemoglobin electrophoresis test?

Ans: It is an electrophoresis test that can be used to the identification of the amount of haemoglobin present in the sample blood.

Introduction

In the lab, chromatography is used to dissect complex mixtures into their constituent parts. The process of separating the components of a mixture is known as chromatography. In order to accomplish this, a mobile phase and a stationary phase are utilised. Since various components in a mixture are subject to varying degrees of influence from the solvent, the mobile phase transports some of the mixture’s components while leaving the stationary phase behind As a result, certain parts will progress quickly while others lag behind. Each component has a unique Rf value. Considering how useful it is in both the purification and analysis processes, it can be found in a wide variety of contexts.

What is the Chromatography technique?

For analytical purposes, a mixture’s distribution into two phases provides a useful starting point for determining how to break it down into its constituent parts. Two such stages are the “mobile” and “stationary” states.

The non-moving phase is called the stationary phase, while the moving phase is called the mobile phase. A glass plate, column, sheet, or anything else is acceptable as the stationary phase. The mobile phase might be either a gas or a liquid.

Since it turns out that every type of molecule has its own unique characteristics. As a result, the Rf value will be unique to each. The Rf number describes how many solute molecules were transported for every one solvent molecule.

Chromatography

What is the Principle of Chromatography?

Chromatography operates on the idea of separating components based on their varied affinities to phases involved. Different components in a combination bind to the mobile phase and the stationary phase with varying strengths.

Applications of Chromatography in the Pharmaceutical Industry

 In the pharmaceutical sector, chromatography is commonly employed as a quality control measure once a chemical has been manufactured.Many different types of chromatography have been used in the pharmaceutical sector. It is employed in both compound analysis and the industrial production of compounds. Separation of chiral substances has also been discovered to benefit from chromatography. 

Applications of Chromatography in the Food Industry

Chromatography has been used for quality control in the food business. Chromatography is useful for determining what kinds of ingredients are in a given dish. Considering the importance of health, it is crucial to pack food with nutrients and vitamins. Several illnesses may be brought on by a deficiency in necessary vitamins and nutrients.

Applications of Chromatography in the Chemical Industry

In the chemical industry, it has applications in the chemical synthesis process. It acts as an assistant for obtaining a particular product. Chromatography has also been used in the pesticide industry for finding the presence of contaminants. For checking the pollutant present in water and air chromatography is used. So it is used in the chemical industry for monitoring several chemical reactions.

Applications of Chromatography in the Field of Molecular Biology

Biological separation using chromatography brings into the world considerable impact on the health and wellness of the people. Without this technique, the preparation method we employ, the synthesis of a particular molecule, etc. will be useless. It has helped researchers to find results faster and with purity. So it has a significant role in molecular biology too.

How is chromatography used in the environmental analysis?

Chromatography has wide application in the analysis of environmental issues. Understanding whether the air is polluted or not is very important since quality air is very essential for the proper living of species. Gas chromatography has been used for this case. 

How is chromatography useful in Forensic Science?

 Chromatography has a vital application in forensic science. For collecting information about the cause of death of a human, chromatography has been employed. It can be used for testing whether a person is infected with some poison, alcohol, drugs, etc. 

Commonly employed chromatography techniques include:

Column chromatography: The stationary phase used in this chromatography is a column and a solvent is used as the mobile phase. Components are separated by their difference in affinity to the solvent. And is used to remove impurities present in a particular compound.

 Ion-exchange chromatography: Separation based on the ions involved in a compound. An ion exchange resin is used as the stationary phase. For water purification, this technique is used.

 Gel-permeation (molecular sieve) chromatography: Separation based on the size of the molecule is gel permeation chromatography. For finding the molecular weight of polymers. This technique is used.

 Affinity chromatography: It is based on specific and highly selective reactions of components present in a mixture. Used for the purification of proteins and nucleic acids.

Paper chromatography: It involves the use of paper as a stationary phase and a solution or solvent as the mobile phase. It is used for purity checking in the pharmaceutical industry.

Thin-layer chromatography: Separation using a thin layer of adsorbent is thin layer chromatography. Mainly used to separate none volatile substances.

Gas chromatography (GS): Separating volatile chemical compounds is gas chromatography. And the mobile phase is a gas stream and a column is used as the stationary phase. It is used widely in the pharmaceutical and cosmeceutical industries.

 Dye-ligand chromatography: Columns pasted with dye ligand act as a stationary phase and are separated with the use of affinity. It is used for protein purification.

Hydrophobic interaction chromatography: This separation of components is based on the hydrophobicity of components. Low water-soluble molecules are separated based on this technique. For example in protein purification. 

 Pseudo Affinity chromatography: The separation of protein molecules by the use of dyes that mimic ligands is pseudo affinity chromatography. It is used in protein purification. 

High-pressure liquid chromatography (HPLC): It involves the use of liquid mobile phase under high pressure and thereby separating molecules from its mixture. It is used in the pharmaceutical industry for the identification of impurities present in it.

Summary

Chromatography is one of the analytical techniques that may be used to separate and purify molecules. It can be used in the pharmaceutical and food industries, among others. Although while analysis is where this technology shines most, it has also been put to use in molecule creation. Chromatography uses two phases—a mobile phase and a stationary phase—to isolate individual substances from a mixture. These phases also serve as a basis for categorising the various chromatographic methods. Methods including gas chromatography, gel permeation chromatography, paper chromatography, high-pressure liquid chromatography, and others are all included.

Frequently Asked Questions

1. What is the difference between flash and preparative chromatography??

Ans: Flash chromatography is used to quickly purify compounds, while preparative chromatography is used to purify compounds with higher resolution.

2. What is isocratic and gradient elution?

Ans: Isocratic elution is used to separate and analyze compounds with a constant mobile phase composition, while gradient elution is used to separate and analyze compounds with a changing mobile phase composition.

3. Which criteria must be followed before selecting a mobile phase?

Ans: Before selecting a mobile phase we need to consider whether it is soluble or insoluble in a particular component that is going to separate. And also need to check the polarity of the compound that has been employed. 

Introduction 

Antonin Prandtl invented the first centrifuge in order to industrially separate milk and cream. Later in 1869, a Swiss researcher and physician named Meischer used centrifugation to separate DNA from the chromosomes in white blood cells. The field of genetics advanced significantly as a result of his work. Thanks to the work of many different chemists and biologists, the centrifuge and centrifugation have progressed and found new uses. Science centres and laboratories all around the world continue to make use of centrifuges and centrifugation to this day.

What is a Centrifuge?

A centrifuge is a machine that maintains a continuous centrifugal force to separate mixtures. It works on the principle of sedimentation. Inside a centrifuge the components of a mixture separate in accordance to their density under the influence of gravitational force. A centrifuge is operated by an electric motor. A centrifuge is a machine that maintains a continuous centrifugal force to separate mixtures. A centrifugal force is an internal force experienced by a rotating or revolving object. Centrifugal force acts outwards and against the direction of the centre of rotation. It works on the principle of sedimentation. Inside a centrifuge the components of a mixture separate in accordance to their density under the influence of gravitational force. A centrifuge is operated by an electric motor.

Usages of a Centrifuge

The centrifuge has vast applications in genetic engineering, medicine, chemistry, pharmacology,  microbiology, biochemistry, molecular biology, analytical chemistry, pathology, biotechnology, physiology and other related areas. 

Types of Centrifuges

The types of the centrifuge are discussed in the below table:

What is Centrifugation?

Centrifugation is a process in which mixtures are separated by utilizing centrifugal force. The centrifugal force is generated by a centrifugal machine or centrifuge when a sample is allowed to rotate. 

Centrifugal Force

A centrifugal force is a force (pseudo) experienced by an object moving in a curvilinear path. It is an apparent force. Centrifugal force acts outwards and against the centre of rotation. The concept of centrifugal force is applied in centrifuges and other similar rotating devices.

Types of Centrifugation

What are the Applications of Centrifugation?

Application of centrifugation involves

• Separation of two miscible substances
• Analysing hydrodynamic macromolecular properties
• Fractioning of subcellular organelles such as membranes
• Fractioning of membrane vesicles
• Separation of chalk powder from water
• Removal of fat and cream from milk to form low-fat milk
• Separation of particles from the air by employing cyclonic separation
• Clarifying & stabilization of wine
• Separation of physiological components such as urine components, blood components in forensic laboratories
• Separation of proteins 

Examples of centrifugation

Some common examples of centrifugation are:

• Centrifugal separation of components of urine, blood and other physiological fluids in pathology labs
• Sludge dewatering in waste treatment
• Cyclonic separation of gaseous components without using filters.
• The process of draining and washing clothes in a washing machine

Principle of Centrifugation

When suspended in a liquid, objects with greater density tend to sink while those with lower densities rise to the surface. As the density gradient widens, the rate of travel quickens. A centrifuge is a device used to apply a strong force perpendicular to the spin axis of an object while it rotates around a fixed axis. Centrifugal force is the term for this pushing outward force. More massive particles scatter outward, whereas less massive ones shift inward and cluster.

Factors that influence Centrifugation

Centrifugation is influenced by a number of factors such as: 

• Densities of solution
• Densities of components of solution
• Temperature 
• Viscosity of sample
• Distance of particle displacement
• Speed or rotation

Summary 

Separating substances by centrifugation is a common laboratory procedure for scientists and engineers. Using centrifugation effectively requires the use of specialised equipment called centrifuges. The solution mixture, process temperature, process type, and separation goal all play a role in choosing the appropriate centrifuge. All centrifuges work on the same basic concept, which is the use of centrifugal force. The use of centrifugation and centrifuges is not restricted to the laboratory; they also have practical applications in the dairy industry, the paint industry, waste management plants, etc. Classical centrifuges from decades past are still in use today.

Frequently Asked Questions

1. What is the difference between centrifugation and filtration?

Ans: Centrifugation and filtration are both methods of separating particles from a solution. The main difference between the two is that centrifugation uses centrifugal force to separate particles, while filtration uses a filter to separate particles. 

2. How can the efficiency of centrifugation be improved?

Ans: The efficiency of centrifugation can be improved by using the correct rotor speed, using the correct centrifuge tube size, and using the correct centrifuge tube material.

3. What is centrifugal distillation?

Ans: Centrifugal distillation uses a combination of centrifugal force and evaporation and condensation to separate particles.

Introduction

Everything in the universe exerts an attractive force on matter around it, which is where the concept of gravitational force comes in. Gravity is one of the four fundamental forces of nature, with the other three being strong nuclear force, weak nuclear force, and the electromagnetic force.

Strong nuclear force is a very short range force that is experienced by nucleons inside whereas charged particles interact via the electromagnetic interaction. Magnetic force is a part of electromagnetic force and we will discuss it here.

Magnet

A material that exerts magnetic force is termed as a magnet. Some elements possess this behaviour naturally, while others can get magnetised when brought inside a magnetic field. This phenomenon is referred to as magnetism and a large number of magnetic materials exist in nature.

Broadly, such materials are classified into three types, which include diamagnetic, paramagnetic, and ferromagnetic materials. At the same time, magnets themselves can be classified into the following:

• There are some materials which exhibit magnetic behaviour and retain magnetic properties over a long period of time. Common examples include iron, nickel, cobalt, etc. and these are classified as permanent magnets. Their magnetic properties are strong.
• Temporary magnets are materials with weak magnetic properties that cannot retain their magnetism. This includes soft iron or steel. 
• Electromagnets are simply materials or circuits that develop a magnetic field when an electric current is passed through them. 

The Bar Magnet

Naturally occurring magnets are irregularly shaped and do not have strong magnetic properties. Using specific ferromagnetic materials, we can construct strong magnets in the shape of a bar, which is what is known as a bar magnet.

            

A bar magnet

Field lines of bar magnets

All magnets have two poles, which are labelled as the south and north poles. One single pole of a magnet cannot exist and the poles are named south and north because of the direction they point if suspended freely. The magnetic field lines or lines of force originate at the north pole and form closed loops to the south pole. Inside the magnet, they go from south to north pole. The magnetic field is the property by virtue of which, a magnet can exert magnetic force on materials around it.

Types of Bar Magnet/ Rectangular Magnet

Bar magnets themselves are further divided into cylindrical and rectangular types. Generally speaking, when we refer to the bar of a material, we expect its length to be much higher than its width, which is true for all bar magnets. However, a bar magnet may also be shaped in the form of a cylinder, giving rise to a cylindrical magnet. This is formed by using a polished, curved surface instead of a rectangular one as in the case of a rectangular bar magnet.

Cylindrical bar magnet

Rectangular bar magnet

Properties of Bar Magnet

1. Like all magnets, bar magnets have a north and south pole, which exist even when the magnet is cut in half. We only end up with two magnets instead of one.
2. Like all magnets, opposite poles of a bar magnet attract while similar poles repel.
3. Bar magnets are designed from materials that can remain magnetised for a long period of time.
4. They attract other ferromagnetic materials.
5. The strength of a bar magnet is higher near the poles than at the centre.

Magnetic Field Lines

The strength and impact of a magnetic material may be determined pictorially via the magnetic field lines. The magnetic field is a vector quantity by virtue of which, magnets can exert magnetic force. Field lines are used to visually represent the magnetic field.

Properties of Magnetic Lines

1. Magnetic field lines can never intersect.
2. Field lines start go from north to south outside the magnet and vice versa inside.
3. Magnetic field lines always form closed loops.
4. The density of magnetic field lines represents the strength of the magnetic field.

Field lines of bar magnet

Pole Strength

Pole strength, represented by m, represent the strength by which materials get attracted to a magnet. We can calculate the Magnetic moment M of a magnet by multiplying its pole strength with its length. The pole strength is measured in A m.

Alnico and Neodymium Bar magnet

Alnico Bar Magnet: Alnico magnets are created by combining Aluminum (Al), Nickel (Ni), and Cobalt (Co) to form a powerful magnet. These magnets are ideal for high-temperature applications and are sold under various names such as Alcomax, Hycomax, Alnico 5, and Alnico 8. They are highly resistant to corrosion and can be cast into complex shapes and larger sizes and at the same time, they prove cost effective as well.

Neodymium Bar magnet: A neodymium bar magnet, also known as a rare earth magnet, has a powerful magnetic field and is available in various sizes. It is composed of neodymium (Nd), iron (Fe), boron (B), and varying amounts of dysprosium and praseodymium. This type of magnet is the strongest of all known magnetic materials. However, it is best suited for use in low-temperature environments and requires a coating to prevent corrosion. Due to the expensive cost of its raw materials, neodymium bar magnets are highly expensive.

Summary

Magnets are materials that have the ability to attract iron, steel, and other such materials towards themselves. One type of magnet is the bar magnet, which is shaped like a bar and is comparatively stronger than naturally occuring magnets. Today, Alnico and Neodymium magnets are two of the strongest permanent magnets used in different settings and a large number of other magnets have also been created for use in various types of situations.

Frequently Asked Questions

1. What is the need for horseshoe-type magnets?

A horseshoe magnet is designed in the shape of a U, which makes it more powerful than other magnets due to the concentration of magnetic field lines at its poles. Because the two poles of a horseshoe magnet are aligned in the same direction, their strength is significantly stronger than other magnets. This makes them suitable for lifting heavy objects.

2. Why do the same poles repel each other and different poles attract each other?

This is a natural property of magnets that may be understood by their field lines. Field lines originate at the north pole and end at the south pole. Thus, when similar poles are brought together, the tendency to form closed loops is disturbed, which results in repulsion.

3. Our earth is like a bar magnet. Explain.

Our Earth behaves like a bar magnet whose field extends thousands of kilometres into space, though it is not very strong.

Earth as a bar magnet

This magnetism is developed in the earth’s core due to the convection current of molten iron and nickel. These particles are charged and thus, constitute a magnetic field

4. State right-hand thumb rule.

The right-hand thumb rule can help us obtain the direction of a magnetic field caused by a current-carrying wire. If we align our thumb along the direction of flow of current, then our fingers curl in the direction of the magnetic field.

5. What are electromagnets?

Electromagnets are created by passing a current through certain current elements like coils or wires. They only remain magnetized as long as the current flows and their strength depends upon the current passed.

Introduction

When it comes to preventing and solving crimes, forensic science is invaluable. It’s utilized as evidence in court to help determine a defendant’s guilt or innocence and to help identify potential perpetrators. From the time the first fingerprint was used to identify a suspect in a murder in the 19th century, forensic science has played a role in the resolution of homicides. A lot of different tools and methods have been added to the field since then. DNA analysis, fingerprinting, ballistics, and toxicology are just a few of the methods used by modern forensic scientists to examine physical evidence.

What is Forensic Chemistry?

Forensic Chemistry would seem to be a branch of chemical sciences that thus combines chemical as well as toxicological techniques to detect unknown factors in such a crime scene. The tests have been performed by forensic chemists, who are experts in their field. To achieve goals, these professionals adopt a variety of tactics as well as techniques. 

What Does a Forensic Chemist do?

It is the job of a forensic chemist, who typically works in such a lab, to analyze evidence found at a crime scene. Investigators are hired by both the government and commercial firms. The samples are collected by the detectives or investigators and then sent to the forensic chemist for analysis. They need to be well-versed in both Organic and Particle Physics. Scientists utilize organic chemistry to analyze body samples for DNA and toxicants.

Role of a Forensic Chemist

A Forensic Chemist’s primary responsibility is to gather substances identified at a crime site and further analyze them to determine how they correlate to the crime. Forensic chemists combine chemistry, physics, as well as biology to discover compounds that could aid in the prosecution of a crime. Their job involves tracing chemicals, narcotics, as well as other substances, and even using methods such as spectroscopy, and chromatography, with the usage of infrared as well as ultraviolet lamps to locate evidence. Most of the samples recovered at crime scenes are retained, but if necessary, testing is performed on them.

Methods used in Forensic Chemistry

Chromatography: Some compounds are unknown but must be disassembled into individual elements for study. Chromatography is indeed the technique of separating the elements of any mixture. The mixture would be first dispersed in a material termed the mobile phase. The mobile phase can then be mixed with the second material, termed the stationary phase, as well as the mixture, which has been separated into two or more substances. It is widely used in investigations involving poisoning, explosives, and so on.

Spectroscopy: It is a method of detecting evidence used within forensic chemistry. This is primarily dependent on both absorptions as well as the emission of light or even radiation by materials as the wavelength of such radiation changes. This even relates to the collisions of electrons, protons, as well as ions.  This procedure is often performed to assess blood toxicity.

Spectroscopy Mechanism

Why a Forensic Chemistry Degree?

After completing their degree, forensic chemists could pursue a variety of careers, including:

• Chemical analyst
• Scientist in Biomedicine
• Investigator at a crime site
• Detective
• Forensic Scientist
• Technician in a scientific laboratory
• Toxicologist
• Secondary school instructor
• Computer forensic specialist
• Officer of the Border Force
• Science professor

Tips to Prepare for Forensic Chemistry

1. Take courses in chemistry, biology, and physics: A strong foundation in these three sciences is essential for success in forensic chemistry.
2. Develop strong laboratory skills: Forensic chemists must be able to accurately and precisely measure, analyze, and interpret data. 
3. Become familiar with the legal system: Understanding the legal system and the role of forensic chemists in it is essential for success in the field. 
4. Learn about the different types of evidence: Forensic chemists must be familiar with the different types of evidence that can be used in criminal investigations. 
5. Develop strong problem-solving skills: Forensic chemists must be able to think critically and solve complex problems. 
6. Become familiar with the latest technology: Forensic chemists must be able to use the latest technology to analyze evidence. 
7. Develop strong communication skills: Forensic chemists must be able to effectively communicate their findings to other professionals. 
8. Get experience in the field: Internships and volunteer opportunities can provide valuable experience in the field of forensic chemistry.

Summary

Forensic Chemistry is a subfield of forensic science. This is an example of chemists’ helping police with their investigations. It really is that important to the study as a whole. A Forensic Chemist is an expert in detecting and analysing substances found at a crime scene using a variety of Forensic Chemistry techniques. If they come upon anything useful, they’ll report it to the detective. Forensic science appears to rely primarily on spectroscopy and chromatography as its primary methods.

Frequently Asked Questions

1. What type of chemical is utilized in fingerprinting?

To expose or even gather fingerprints, forensics experts use four basic chemicals: silver nitrate, ninhydrin, cyanoacrylate, as well as iodine. Certain chemicals react to elements within fingerprint, including oil as well as perspiration, changing the colour of the print and therefore, allowing experts to see it better.

2. What methods do forensic scientists use to examine drugs?

In most cases, forensic drug testing is conducted in 2 stages: screening as well as confirmation. When drugs are found via screening, such as spot test kits, samples have been collected and then forwarded to labs for confirmation testing.

3.Who is considered the father of forensic chemistry?

The “Father of Toxicology,” Mathieu Joseph Bonaventure Orfila (1787-1853), was the very first prominent nineteenth-century pioneer of forensic science. He tried to form chemical analysis, a common aspect of forensic medicine, but also researched asphyxiation, body decomposition, as well as exhumation.

Introduction

Colloids are a type of mixture in which one material is broken down into tiny particles (known colloidal particles) and spread throughout another. The particles are larger than those found in the solution, yet they are too small to be seen using a microscope. There are no precise size limits for colloidal particles, however, they tend to be in the 10-9m to  10-6m. Preparation of colloids can be done by two methods: dispersion and condensation methods.

What are Colloids?

Colloids are a special kind of mixture in which one substance is dispersed throughout another after being broken down into very small pieces (the “colloidal particles”). Despite being larger than the particles in the solution, they are still too small to be seen with the naked eye.

Colloidal particles can have any size from \({10^9}m\;to\;{10^6}m\) , but typically fall into that range. There are two ways to get colloids ready for use: dispersion or condensation.

Examples of Colloids

Here are several examples of colloids:

• Solid Sols- Pearl, some alloys, gemstones, etc.
• Gels- Gelatin, jelly, etc.
• Aerosols- Fog, clouds, dust, etc.
• Solid Foams- Marshmallows, Styrofoam, etc.
• Emulsions- Milk, lotion, etc.
• Foams- whipped cream, shaving cream, etc.
• Sols- Ink, shampoo, etc.

Classification of Colloids:

Based on Physical State

We can divide colloids into 8 groups:

• Foam
• Emulsion
• Solid aerosol
• Gel
• Solid sol
• Solid foam
• Aerosol
• Sol

Based on Interaction Forces

Lyophilic colloids

Solutions have a colloidal particle size in which the particles of the dispersion phase are evenly distributed and exhibit a high attraction for the dispersed phase known as lyophilic colloids. These sols are quite stable and do not coagulate quickly. Gums, and proteins, along with other lyophilic colloids, are examples.

Lyophobic colloids

Colloidal solutions wherein the dispersed medium particles have no attraction to the dispersion medium are known as lyophobic colloids. For the sake of preservation, these sols require some stabilizing chemicals.

Classification Based on Properties of Sol Particle

Multi Molecular Colloids

When a substance disintegrates, atoms/ molecules clump together to produce colloidal particles. Multimolecular colloids are the particles that result from this process.

Macromolecular Colloids

These are macromolecular colloids, which are macromolecular substances with large molecular sizes that, when broken down, generate a size in the colloids. As a result, the macromolecules that make up the dispersed phase are usually polymers with extremely high molecular weights.

 Based on Dispersion Medium

It can be categorized into four categories based on the dispersion medium:

Preparation of Colloid Solutions:

Condensation method

•  By exchange of solvent,  An S or P solution in alcohol is emptied into \({{\bf{H}}_2}{\bf{O}}\) to form a colloid of  S or P due to its limited water solubility.
•  By change of physical state S or Hg, for example, can be turned into colloidal solutions by transporting their vapours through a stabiliser-laced cold water
• Chemical Methods: Double decomposition: To make \(A{s_2}S\) sol, a constant stream of  \({{\bf{H}}_2}{\bf{S}}\)  gas is fed through such a freezing solution of \(A{s_2}{O_3}\) . This process is continued until the sol’s yellow colour reaches its maximal intensity.
• Oxidation: When \({{\bf{H}}_2}{\bf{S}}\) is passed through \({\bf{S}}{{\bf{O}}_2}\) solution, it forms a colloidal solution.
• \({\bf{2}}{{\bf{H}}_2}{\bf{S}} + {\bf{S}}{{\bf{O}}_2} \to \;{\bf{2}}{{\bf{H}}_2}{\bf{O}} + {\bf{3S}}\)     
•  By excessive cooling:  By freezing a water solution in an organic solvent such as ether/\(CHC{l_3}\), a colloidal ice solution can be created. 

Dispersion Methods

Mechanical dispersion

A colloidal mill is used to grind the solid and liquid together. The colloidal mill is made up of two steel plates that are closely touching and revolving at high speeds in opposite directions. This process is used to create colloidal graphite and printing inks.

Bredig’s Arc Method

Colloids of metals such as gold, platinum, as well as silver can be made using this method. Under the surface of the water with a stabilizing substance, such as a little amount of alkali, an arc is produced between metal electrodes.

Peptisation 

Peptisation is the activity of an electrolyte in a solution to disperse a precipitated substance into a colloidal solution. A peptizing agent is an electrolyte employed.

Purification of Colloids:

Dialysis:

The principle behind dialysis is that colloidal particles cannot flow through parchment or cellophane membranes, but electrolyte ions may. Dialysis is the technique of removing colloidal particles from contaminants by diffusing them through a suitable membrane.

Electro-dialysis:

When an electric field is created between the electrodes, the ions in the electrolyte that are present as impurities diffuse rapidly approaching oppositely charged electrodes. The electric field is needed for this.

Ultrafiltration:

The pores of typical filter paper are large enough to allow both impurities and colloidal particles to pass through. Ultrafilters are the resultant filter sheets. Ultrafiltration is the process of filtering through ultrafilters.

Commercial Applications of Colloid

In pharmacy:

Because colloidal drugs are easily absorbed by biological tissues, they are much more efficacious.

 In environment:

Purification of water: Some electrolytes, like alum, can be employed to precipitate colloidal pollutants in water.

 In industrial products:

Rubber industry: Latex is made up of negatively charged rubber particles suspended in a colloidal fluid. Rubber can be made from latex via coagulation.

In the field of defence:

Colloids are employed in defence in the form of smoke in smoke screens to disguise anything in the military. Colloids are employed in rocket technology. A colloid thruster is used in rockets.

Summary

Colloids, then, are a type of mixture in which one component is spread throughout another substance after being broken down into extremely small particles. Colloidal solutions contain particles of sizes between 1 nanometer and 500 nanometers, which are in between those of a real solution and those of a pure solution. It is typically categorised as a 2-phase, heterogeneous/homogeneous system, depending on the conditions. Colloids are dispersed mixtures in which the suspended particles do not sink to the bottom.

Frequently Asked Questions

1. What is Ultracentrifugation?

Ans. It is the process of using centrifugal force to separate colloidal particles from contaminants. The impure sol is collected in a tube, which is then placed in an ultracentrifuge.

2. Why are the colligative properties of colloids of low order?

Ans. Because colloidal particles are larger aggregates, the particles in colloids are smaller than in a true solution. As a result, when compared to true solution values at similar proportions, measurements of colligative qualities are of low order.

3. What is the Tyndall effect?

Ans. The Tyndall effect confirms the colloidal solution’s heterogeneous character. As light travels through a sol, it is scattered by particles, revealing its route and called the Tyndall effect.