Category: Chemistry Notes PPT

Feldspar refers to a group of minerals that contain alumina and silica (SiO₂) in their chemical makeup, and are natural minerals. Feldspar can be described as a large group of rock-forming silicate minerals. Aluminum silicates of soda, potassium, or lime belong to this group of natural minerals. This is a common mineral group and makes up about 60% of the exposed rocks, as well as sand, clay, and other unconsolidated sediments, and are important parts of rock classification schemes. Included in this group are orthoclase, microcline, and plagioclase feldspars.

Chemical Formula of Feldspar

Potassium feldspar chemical  formula or (K-spar) formula- KAlSi₃O₈

Sodium feldspar chemical formula or albite formula- NaAlSi₃O₈

Calcium feldspar chemical formula- CaAl₂Si₂O₈.

Bowen’s Reaction Series

Alkali feldspar is a solid solution between K-feldspar and albite and the Solid solutions that are found between albite and anorthite are called plagioclase, also known as plagioclase feldspar. A limited solid solution occurs between K-feldspar and anorthite, and in the two other solid solutions, immiscibility occurs at temperatures common in the crust of the Earth. Albite is used as plagioclase and also as alkali feldspar.

Calcium-rich Plagioclase is the first feldspar that crystallizes from cooling magma, but with the progress in crystallization, the plagioclase gradually becomes sodium-rich.

The structure of  Feldspar is based on Aluminosilicate tetrahedra, where each of the tetrahedra has an aluminum or silicon ion which is surrounded by four oxygen ions. It forms a three-dimensional network, each oxygen ion is shared by a nearby tetrahedron. Here, we can see long chains of aluminosilicate tetrahedra which are often called the crankshaft chains.

Properties of Feldspar

Feldspar has different chemical formulas each depending on its composition.  The specific chemical formula is KAlSi₃O₈ – NaAlSi₃O₈ – CaAl₂Si₂O₈.

The minerals are chemically alert and have a stable pH value.

In the Physical properties of Feldspar, we can say that the Feldspars have a monoclinic or a triclinic crystal system and the refractive index of this mineral is 1.518 – 1.526. 

The cleavage of feldspar is two and it consists of two planes that intersect each other at an angle of 90º. On the Mohs hardness scale, the hardness of this mineral is 6 – 6.5. The density of Feldspar is 2.56 g/cm3 and the double refraction is of the first order. Feldspar has a conchoidal or a brittle fracture that can be noticed along the cleavage planes. Feldspar consists of a vitreous, pearly luster with a white streak. Feldspars are not known to have any kind of optical phenomenon.

 

Feldspar is the name given to a group of minerals that have alumina and silica (SiO₂) in their chemical makeup. Aluminum silicates of soda, potassium, or lime belong to this group of natural minerals. This natural mineral is the most common mineral group on the planet. They make up about 60% of exposed rocks, as well as sands, clays, and other unconsolidated sediments, and are important parts of rock classification schemes. The orthoclase, microcline, and plagioclase feldspars are included in this group. The subject of feldspar has been thoroughly discussed in this article. We’ve covered everything you need to know about feldspar, including its chemical name, uses, structure, and history.

 

Feldspars form intrusive and extrusive igneous rocks from magma, and they’re also found in a variety of metamorphic rocks. Anorthosite is a rock composed almost entirely of calcic plagioclase feldspar.

 

Feldspars can be present in a wide variety of sedimentary rocks. Feldspars are potassium and aluminium salts, sodium and aluminium salts, and calcium and aluminium salts, respectively. Potassium aluminium silicates (KAlSi₃O₈), sodium aluminium silicates (NaAlSi₃O₈), and calcium aluminium silicates are the chemical names for feldspar (CaAl₂Si₂O₈). The form of alkali metal or alkaline earth metal found in the molecule determines the chemical name of feldspar. These minerals are a class of rock-forming tectosilicate minerals that account for around 41% of the continental crust’s weight.

Feldspar Composition

Tectosilicates, or silicate minerals, are a type of natural mineral. Silicon ions are connected by shared oxygen ions to form a three-dimensional network in this type of mineral. Three endmembers may be used to express the compositions of major elements in common feldspar. Let’s look at the chemical formulas for various forms of feldspar.

Feldspar Structure

Aluminosilicate tetrahedra make up the backbone of feldspar crystals. An aluminium or silicon ion is surrounded by four oxygen ions in each tetrahedron. A three-dimensional network is formed when each oxygen ion is shared by a neighbouring tetrahedron. Long chains of aluminosilicate tetrahedra can be seen, which are often referred to as crankshaft chains due to their kinked form. Each crankshaft chain forms a three-dimensional network of fused four-member rings by connecting to neighbouring crankshaft chains. The structure is open enough for cations (usually sodium, potassium, or calcium) to fit inside and balance the charge.

Types of Feldspar

Alkali feldspars are grouped into two types: 

1. Containing potassium in combination with sodium, aluminium, or silicon.

2. Containing barium (barium replaced potassium). 

The first of these include:

• Orthoclase (monoclinic) KAlSi₃O₈

• Sanidine (monoclinic) (K,Na)AlSi₃O₈

• Microcline (triclinic) KAlSi₃O₈

• Anorthoclase (triclinic) (Na,K)AlSi₃O₈

Potassium and Sodium Feldspars 

Since these aren’t perfectly miscible in the melt at low temperatures, intermediate alkali feldspar compositions can only be found in higher-temperature settings. Sanidine is stable at high temperatures and microcline is stable at low temperatures. Perthite is a common texture in alkali feldspar, resulting from the exsolution of different alkali feldspar compositions during the cooling of intermediate composition. Many granites have perthitic textures in their alkali feldspars that can be seen with the naked eye. With a light microscope, one can see micro perthitic textures in crystals, but only an electron microscope can see crypto perthitic textures.

 

The QAPF classification of igneous rock is based on the ratio of alkali feldspar to plagioclase feldspar, as well as the proportion of quartz. Plagioclase, which is calcium-rich, is the first feldspar to crystallize from a cooling magma, but as crystallization progresses, the plagioclase gradually becomes sodium-rich. The continuous Bowen’s reaction series is described by this. The last feldspar to crystallize from the magma is K-feldspar.

Barium Feldspars

Alkali feldspars are also known as barium feldspars. Barium feldspars are formed when barium is substituted for potassium in the mineral structure. The monoclinic barium feldspars contain the following:

The triclinic plagioclase feldspars are a type of plagioclase feldspar. The following is the plagioclase series (with percent anorthite in parentheses):

1. albite (0 to 10) NaAlSi3O8

2. oligoclase (10 to 30) (Na,Ca)(Al,Si)AlSi₂O₈

3. andesine (30 to 50) NaAlSi₃O₈–CaAl₂Si₂O₈

4. labradorite (50 to 70) (Ca,Na)Al(Al,Si)Si₂O₈

5. bytownite (70 to 90) (NaSi,CaAl)AlSi₂O₈

6. anorthite (90 to 100) CaAl₂Si₂O₈

Plagioclase feldspar with intermediate compositions can also exsolve to two feldspars with contrasting compositions during cooling, but diffusion is much slower than in alkali feldspar, and the resulting two-feldspar intergrowths are usually too fine-grained to be visible with optical microscopes. In comparison to the difference in alkali feldspars, the immiscibility differences in plagioclase solid solutions are more complicated. The colour play apparent in some feldspar of labradorite composition is due to Boggild intergrowth, which is a very fine-grained exsolution lamellae. From albite (2.62) to anorthite (2.72–2.75), the specific gravity of the plagioclase sequence increases.

Uses of Feldspar

• Dinnerware, bathroom and construction tiles are all made of feldspar.

• In the manufacture of ceramics and glass.

• As a flux, feldspar is used. A flux is a substance that decreases the melting temperature of another substance, such as glass in this case.

Substitutes and Alternative Sources of Feldspar

Other minerals and mineral mixtures with identical physical properties may be substituted for feldspar. Pyrophyllite, clays, talc, and feldspar-silica (quartz) mixtures are some of the minerals that could be used to replace feldspar. For the near future, these substitutions would be unnecessary due to the abundance of feldspar.

Mining of Feldspar

North Carolina, Virginia, California, Oklahoma, Idaho, Georgia, and South Dakota, in order of estimated tonnage, are the top states producing feldspar. Mica and silica sand were recovered as co-products by feldspar processors.

 

Feldspar is mined from large granite bodies (called plutons by geologists), pegmatites (formed when a crystallizing granite’s last fluid stages become concentrated in small liquid and vapor-rich pockets that allow the growth of extremely large crystals), and feldspar-rich sands.

 

Since feldspar is such a large component of the Earth’s crust, it is believed that feldspar supply would be sufficient to satisfy the demand for a very long time. The demand for raw feldspar is currently being met by existing mines around the world.

 

Hard-rock feldspar mining is achieved by open-pit methods by the mine owner or by contractors. Secondary breakage is done with a traditional drop ball after the feldspar ore has been drilled and blasted. The ore is then loaded onto trucks using a hydraulic shovel and hauled to the crushing facility, which is located near the flotation plant.

Weathering of Feldspar

Hydrolysis causes chemical weathering of feldspars, resulting in clay minerals such as illite, smectite, and kaolinite. The first step in the hydrolysis of feldspars is for the feldspar to dissolve in water, which occurs better in acidic or basic solutions and less so in neutral solutions. The rate at which feldspars are dissolved determines how easily they weather. Clays are formed when dissolved feldspar reacts with H+ or OH ions. The reaction also produces new ions in solution, with the form of feldspar reacting controlling the variety of ions produced.

 

Clays are plentiful weathering materials due to the presence of feldspars in the Earth’s crust. Clays make up about 40% of the minerals in sedimentary rocks, and clays are the primary minerals in mudrocks, the most common sedimentary rocks. They’re also an integral part of the soil. Clay-replaced feldspar appears chalky in comparison to unweathered grains of feldspar, which is more crystalline and glassy.

 

Due to their high formation temperature, feldspars, especially plagioclase feldspars, are not very stable at the earth’s surface. Feldspars are quickly weathered to clays due to their lack of stability. Feldspars are rarely found in sedimentary rocks due to their proclivity for weathering. Significant concentrations of feldspar in sedimentary rocks suggest that the sediment was not subjected to much chemical weathering before being buried. This indicates that it was most likely transported a short distance in cold or dry conditions that slowed weathering and were easily buried by other sediments. Arkoses are sandstones that contain a lot of feldspar.

Feldspar as a Mineral

Feldspars are the most common and widespread rock-forming minerals, making up the majority of major rock types including granites and gabbros. They are aluminosilicates, which undergo complex reactions when cooled from melts or metamorphosed at high temperatures due to the ordering of Si and Al.

 

Below 600 °C, there is a limited solid solution in the alkali feldspars between the albite and sanidine end members. A solid solution is also common between the end members albite and anorthite in plagioclase feldspars, with more unmixing occurring below 400 °C.

 

Even when the feldspar crystals are very thin, these consistent properties of feldspar are extremely useful. People who are familiar with feldspar cleavage can pick up an igneous rock with a few millimeter-sized crystals, analyze it with a hand lens, and easily distinguish the feldspars from the other minerals in the rock. They may also use a set of mineral hardness picks and a hand lens to assess the Mohs hardness of such tiny grains with a little practice.

Did You Know

• Feldspar is a mineral that accounts for up to 60% of the Earth’s crust.

• Feldspar is divided into two types, both of which are composed of silica and aluminium.

• In 2010, about 20 million tons of feldspar were produced, mainly by three countries: Italy (4.7 million tons), Turkey (4.5 million tons), and China (4.5 million tons) (2 Mt).

• Feldspars are used for K-Ar dating in earth sciences and archeology.

Flocculation meaning is a process that helps in forming large aggregates of particles. For this to occur, a chemical coagulant gets added to the liquid. This coagulant facilitates the bonding of the particles in the liquid. According to IUPAC, the flocculation definition states that it is a process of contact and adhesion through which the dispersed particles form large clusters. The particles that are together can easily loosen up due to the surface tension of the liquid. Flocculation has numerous applications. Sometimes flocculation may be undesirable for the process. Hence, the removal of flocculants takes place. Water supplies, water treatment plants, and even sample processing are some applications that require flocculation. 

Natural Flocculation

Natural processes of flocculation treat wastewater. Natural flocculants are environment-friendly. Seeds of plants like ovata, Oliveira, moringa, or Plantago are for this purpose. Starch is a natural product that can also act as a natural flocculant. Using natural resources like these makes the processes of waste management cost-effective. One of the main advantages of these flocculants is that they are biodegradable and can be renewed and used. Using these materials is preferable as they are non-toxic. No toxic reaction should affect the purification. Natural flocculants are very safe to use but their lifespan is less. 

Chemical Flocculation

The chemical flocculants ensure a very effective treatment in coagulation processes. As suggested by the name, they are chemically synthesized from various monomers from electrolytes, cationic, anionic as well as nonionic polymers. However, these chemical flocculants produce toxicity as suggested by many studies. They produce sludge with a high concentration of metal hydroxides that are harmful to living beings if released into the water bodies. 

Alum, Aluminium chlorohydrate, or aluminum sulfate are different kinds of organic flocculants used to treat water. The cationic flocculants are available in the largest number of varieties and hence are used the most. The chemical flocculants are mainly useful as they allow techniques like copolymerization to occur. The nonionic flocculants have very low surface charge and can only function through certain bridging mechanisms, in an aqueous medium. 

Application of Flocculation

There are several fields where the process of flocculation is applied. Some flocculation examples are given below:

• Flocculation helps in emulsion, where each droplet comes together to form a cluster. It has usage in mineral dressing or to design the physical properties of pharmaceutical products.

• Flocculation processes induce eutrophication through the adsorption of substances from underwater. It also maintains the freshwater quality under the soil. Thus the formation of colloids helps in these processes.

• Due to the hydrolysis of molecules and the micro peptides, flocculation is used extensively in the cheese industry. During the manufacture of cheese, this process determines the time required for the formation of the curd.

• During construction work, flocculation helps in the coagulation of clay particles and polymers by mechanical agitation. This process leads to the formation of structures spontaneously. It is due to the attraction of the positive and negative charges. Hence, these applications are important for civil engineering processes.

• Flocculation is used in many biological and biotechnological processes. The process of microfiltration and flocculation go hand in hand. Synthetic flocculants in the bioreactor increase in size and hence help in the purification process.

• Processes such as coagulation, flocculation sedimentation treat the stormwater, sewage, or industrial wastewater. Drinking water also requires such treatments.

• In the brewing industry, yeast gets flocculated. It helps in the fermentation of beer. The yeast gets sedimented and floats down to the base or the top, from where it can be separated. This yeast gets reused for fermentation. 

Questions and Answers

1. How Can Efficient Flocculation Be Carried Out?

Answer: Flocculation is an essential process in the purification of substances. It is a widely used process used in industries. One of the main things is that the phenomenon should be very cost-effective. Precious metals, particulate matter, fibers, and fillers, or even water impurities can be accumulated through efficient processes. These processes are:

• Flocculants are selected carefully. Natural flocculants have the lowest toxicity rate. Metals and other such substances require cationic and anionic flocculants.

• There are several parameters related to the process of flocculation like mixing intensity, time, shear stress, concentration, the particle size of the solid, and the dosing rate and location. The value will differ according to the requirement.

• There must be a downstream flow of the particles.

2. Describe the Floc Breakage Kinetics.

Answer: Stirring is an essential process in flocculation. Fast stirring can break the floc. It causes the number of particles to become of the same density and size as before flocculation. Therefore, a very gentle stirring is required. The different particles have varied flocculation strength. Hence the stirrer rpm is determined to understand which value is more suitable for which variety of floc. Slow stirring leaves most flocs intact. The intensity of the combination, if carefully set, prevents the breaking of the flocs, stopping the increase in filtration time as well. 

Free radicals are a set of impaired electrons present in almost every molecule, which combines with other constituents very quickly and gives the results accordingly. Many organic molecules have a concise life, and that is why even free radicals need to multiple themselves from time-to-time to avoid getting destroyed entirely from a single body.

In Chemistry, a free radical is an atom or a molecule free in its space and independent in its nature. The molecules that have unpaired electrons are called free radicals, and such radicals can be easily mixed with their respective components without getting affected by the outside atmosphere. 

These free radicals play a vital role in the proper functioning of the body, and that is why there should be more presence of them in humans’ bodies.  

There are a lot of examples of free radicals in chemistry, which primarily consists of Nitric Acid (NO), Hydrogen Peroxide (H2O2), Hydroxyl radical (OH), and so on.

Types of Free Radicals

 There are two types of free radicals. They are-

These free radicals do not charge them that’s why they have a much lesser reactivity than the charged free radicals.  

The free radicals charged are very strongly reactive and emit great capacity to mix with the other components and constituents. These free radicals can either be positive or negative.

What Causes Free Radicals?

Sometimes, the metabolic processes that seem to be expected in the body cause free radicals. These metabolic processes are the essential and required processes of the body, and that is why total eradication of the same is impossible and unhealthy for the body. 

Free radicals can also get into the body by external sources such as X-rays, cigarette smoking, etc.

The free radicals in the body of living beings cause quick combinations with the other components and also form large reaction chains for the same reason. These radicals are very quick to react with every molecule, and these reactions are precisely termed ‘oxidation reactions’ in living beings, especially humans.  

Properties of Free Radicals

There are various properties of free radicals that can be listed with short details as below-

Due to the free radicals’ unstable nature, they can attract and combine with any chemical component very easily and freely.  

The free radicals’ reactivity is very high, which makes it available and open for the other components to come and merge with them. The free radicals’ above properties make them unique and useful for the people in their bodies and from any other outside source. The primary and most crucial task of free radicals is to combine with the other free components present in your body. In this process, the free radicals may sometimes cause acceleration of heart disease and some other minor disorders.  

What are Free Radicals in Food?

Some specific foods have a massive amount of free radicals present in it. These foods can be stated as below-

The glycemic foods that are present in the market are a very active source of free radicals, and their consumption can give you ample free radical benefits for sure.  

Processed meats like sausages, salami, and bacon are rich in free radicals, and that is why these foods should be consumed in vast amounts if you want to increase the number of free radicals in your body.

Free radicals can sometimes cause significant loss to your body, but the other times, it is a precious and essential component present in your body. So, it would help if you actively contributed to increasing the number of free radicals in your body by consuming rich foods. 

Furfural is an organic compound obtained during the dehydration of sugars. Its IUPAC name is furan-2-carbaldehyde. The word, furfural comes from the Latin word furfur that stands for bran, its usual source. Sugars present in a variety of agricultural byproducts such as corn cobs, oats, wheat bran, and sawdust are used to produce furfural. It is commonly used in many processed foods and beverages.

Furfural is a colourless liquid that darkens on exposure to air. It is the best-known member of the furan family. Furfural meaning is furfuraldehyde or also called 2-furaldehyde. It is also an important source of other furans. The boiling point of furfuraldehyde is 161.7⁰C. The furfural structure is given below:

Furfuraldehyde

The chemical formula for furfuraldehyde or furfural aldehyde is C₄H₃O-CHO. In 1922, Quaker Oats company started producing furfural from oat hulls for commercial use much after its discovery by a German scientist Johann Wolfgang in 1821. The industrial development of the production of furfural is a great example of how industries utilize agricultural residues. The major raw material source of furfural such as corncobs, oat hulls, cottonseed hulls, rice hulls, and bagasse are replenished annually ensuring a constant supply of raw material for the production of furfural.

In large rotary digesters, lots of raw material and dilute sulphuric acid are steamed under pressure. The furfural form is continuously removed with steam and then concentrated with the help of distillation. The furfural obtained by distillation separates into two layers of condensation and the wet furfural at the bottom is dried with the help of vaccum distillation to obtain furfural with a minimum of 99% purity. Given below is the dehydration reaction of pentoses under an acid catalyst.

C₅H₁₀O₅ → C₅H₁₀O₂ + 3H₂O

The furfural price remains stable in the market and is readily available at Furfural sigma Aldrich. Global demands of furfural remain high with China as its leading production capacity of 85% and consumption of 75%.

Properties of Furfural

Furfural has a molecular weight of 96.08 g/mol. It is denser than water and water-soluble. Its vapours are heavier than air. It has a distinct caramel taste and smells somewhat like benzaldehyde. It has a boiling point of 161.7⁰C. It is considered a major platform chemical that is used in the production of various other chemicals. 

Furfural strongly resembles benzaldehyde in its reactions as an aldehyde. In the presence of strong aqueous alkali, it undergoes a Cannizaro reaction. It dimerizes furoin under the influence of potassium cyanide and by the action of ammonia is converted into hydro furamide  (C₄H₃O-CH)₃N₂.

On exposure to air at room temperature, furfural degrades into formic acid and formerly acrylic acid. Furoic or furfural acid is a crystalline solid, white in colour, and is used as a bactericide and a preservative. Its esters are fragrant liquids commonly used in perfumes and flavourings.

Methyl Furfural

5-methyl 2-furaldehyde is an arenecarbaldehyde that is slightly soluble in water and is used as a food flavouring agent. It is also used as a fragrance agent for in-home products or similar industrial products.

Hydroxymethyl Furfuraldehyde

5-hydroxy methyl furfural is an organic compound obtained upon dehydration of sugars, which is highly soluble in water and organic solvents.  It is used as an additive agent in the food industry and also in the production of various fuels and chemicals. It is absent in fresh food but is naturally generated upon heating of sugar-containing food items.

Conclusion

Furfural is one of the furan derivatives from hemicellulose present in lignocellulosic. It is naturally obtained upon dehydration of xylose, which is a pentose sugar. This heterocyclic and aromatic aldehyde consists of an aldehyde side group and a furan ring. It is a colourless liquid and has an oily appearance with an almond-like odour. Furfural has various industrial purposes being a platform chemical that is used in the production of various other chemical compounds. It is also used in the production of furan compounds. 

Specific reactions are known to be spontaneous as they give off energy in the form of heat (H < 0). Interestingly, a few other spontaneous reactions result in an increase in the disorder of a system (S > 0). Therefore, calculating H and S can identify the actual forces behind such reactions.

Furthermore, when one such force behind a reaction is favoured, and others are not, Gibbs free energy (G) is used to identify those results. Moreover, it also reflects the balance between these reactions. 

What is Gibbs Free Energy?

In thermodynamics, Gibbs free energy is known as a thermodynamic potential. Moreover, this potential is used to calculate the optimum of reversible work that one thermodynamic system can perform at constant pressure and temperature. Additionally, the measuring unit of Gibbs free energy is Joules in SI. 

Furthermore, when a thermodynamic system transforms reversibly from its initial state towards its final state; the decrease in Gibbs energy is similar to the work done by this system and its surroundings. However, the work of pressure forces is not considered here.

Besides, this thermodynamic potential is minimised when a system reaches its chemical equilibrium at a constant temperature and pressure. Furthermore, the derivative of this system with respect to its reaction coordinate vanishes at this equilibrium point. Hence, a reduction in Gibbs free energy is needed to make such reactions spontaneous.

History of Gibbs Free Energy

The quantity termed as “free energy” is an advanced and accurate replacement for the archaic term “affinity”. This term was used by chemists in the initial years of physical chemistry to portray the forces behind chemical reactions.

Furthermore, in 1873, Josiah Willard Gibbs published his paper, “A Method of Geometrical Representation of the Thermodynamic Properties of Substances by Means of Surfaces”. In this journal, he mentioned the principles behind his new equation, which can predict or estimate the propensities of a different natural process which follows when these systems or bodies come in contact with each other. 

Moreover, in this paper, Gibbs identified three states of the above mentioned equilibrium. They are “necessarily stable”, “unstable”, and “neutral”. Additionally, he also mentioned whether any changes would follow or not. He arrived at this conclusion by understanding the interactions between homogeneous substances in contact. Furthermore, he used a three-dimensional volume-entropy-internal graph to study substances, which are part-solid, part-liquid and part-vapour.

Additionally, in another paper “Graphical Methods in the Thermodynamics of Fluids,” Gibbs outlined how his equation has the capability to assume the behaviour of systems when they are mixed. Moreover, this quantity here is associated with chemical reactions that can do the work. It also represents the sum of its enthalpy and product of its temperature and entropy. 

The Gibbs energy formula that defines this quantity is G=H -TS, or more completely as G=U+PV-TS. In this equation –

• U is internal energy with SI unit joule.

• P is pressure where the SI unit is pascal.

• V is a volume with SI unit m3T is temperature, and the SI unit is Kelvin.

• S is entropy with SI unit kelvin/joule.

• H is enthalpy where SI unit is a joule.

Gibbs Energy Reactions

Spontaneous Process

In chemistry, Gibbs energy change spontaneity of a process is the one that does not require any external energy. Moreover, it is considered natural as it occurs itself, without any outside influence. The spontaneous process can be quick or slow because it is not associated with kinetics rate. A prominent example of spontaneous reaction is diamonds turning into graphite. 

Additionally, over a long period, the carbon in the diamond slowly becomes more stable and less shiny, graphite. However, this process takes a long time, and it is hard for any human being to survive and witness this phenomenon. 

Furthermore, another point to remember here is that this process can be endothermic, as well as exothermic. 

How to Determine a Spontaneous Reaction?

The easiest way to understand this situation while solving an equation is if G is negative, then it is spontaneous. Otherwise, it is non-spontaneous, as it requires a continuous supply of external energy. Therefore, the Gibbs free energy symbol, i.e. G, can be ideally considered as “standard free energy charge”. 

Furthermore, as per the second law of thermodynamics, every spontaneous process raises the entropy of the universe. However, using this law to calculate a spontaneous reaction can be a little difficult. Chemists are usually interested in changes happening around them. Typically, it is a reaction in a beaker. Therefore, there is no need to investigate the entire universe, t understand a small change.

Thus, chemists use Gibbs free energy change to study such reactions. This new thermodynamic quantity helps researchers to determine entropy changes in the universe. Moreover, chemical reactions involving such thermodynamics quantities, variations of the following equations are often witnessed –

Moreover, this reaction, which does not have any subscript that specifies the thermodynamics values are for the system. Nevertheless, it is still considered that the values of H and S here are of the system of interest. 

Additionally, this equation is vital and exciting, as it permits to calculate the alterations using enthalpy and entropy changes. Furthermore, the G here can be used to figure out whether a reaction is spontaneous in forward or backward direction, or at equilibrium.

• Moreover, when G<0, this process is exergonic. It will move forward spontaneously and produce other products.

• However, if G>0, it is an endergonic process. Thus, it is not spontaneous in the forward direction. Instead, it will move freely in the reverse direction and produce other starting materials.

• On the other hand, when G=0, it reaches an equilibrium. Hence, the mixture of the products and reactants remains constant.

Spontaneity and Gibbs Free Energy

Furthermore, when any reaction occurs at a constant pressure P and constant temperature T, the second law of thermodynamics can be arranged for Gibbs energy define. Moreover, while using Gibbs free energy to determine the spontaneity of a process, the focus is on G. Thus, the absolute value is not considered here. Hence, the value of G in this process is the difference between its initial value and its final value.

Remarks on Gibbs Free Energy

The title “free energy” used to determine G has led to a lot of confusion. Thus, researchers these days primarily refer to it as Gibbs energy.

• Notably, this term “free” is a part of the older portrayal related to the steam engine origin of thermodynamics. It has only interest in converting heat into work. Here G stands for the optimum amount of energy, which can be extracted from this system to execute useful work. Furthermore, here ‘useful’ means any work which is not associated with the system expansion.

• Another serious difficulty of Gibbs energy change is in the framework of Chemistry. Even though G is calculated in the units of energy, it does not have a vital feature of energy, i.e. conservation. Even though energy levels fall due to any spontaneous chemical reactions, there is no increase of energy anywhere else. Hence, referring to G as energy is somewhat a misleading notion. 

• G has no thermodynamics quantities like H and S, as it has no physical reality like property of matter. Moreover, H and S stand for the quantity and distribution of energy in molecules, respectively. Hence, this free energy is just a useful construct, which serves as a term for a change to make the calculations easier. 

Furthermore, the Gibbs free energy is vital in researches as it enables one to predict the direction of a reaction. Moreover, this ability to calculate G plays a significant role in designing lab experiments. Apart from that, it is also an essential chapter of Chemistry, and students should prepare it well for their exam.

Additionally, students can seek assistance from to prepare various chapters of Chemistry. They can download our official app, and join the live classes by subject experts. Moreover, they can also access study materials, mocks tests, etc. to improve their preparations.

Environmental concerns have increased the rates of global warming due to the greenhouse effect. The normal temperature of the earth has seen a high shift due to the absorption of solar energy. The greenhouse gases present in the atmosphere absorb this heat energy and disrupt the regulation of heat throughout the atmosphere. As a result, the temperature rises, resulting in global warming. Some of the greenhouse gases are methane, carbon dioxide, ozone, chlorofluorocarbons, etc.

What Are The Effects of Global Warming?

Global warming causes some of the most hazardous effects on the human, animal and plant population. Some of the most devastating global warming effects are as follows.

It is one of the greatest effects of global warming.

The rise in temperature has resulted in the melting of solid bodies like icebergs and glaciers. This also results in the rise of floods in different states.

Countries like Africa have suffered from major drought seasons. This is because of the drying of the water bodies and the absence of necessary conditions for crop growth.

Due to the melting of icebergs and glaciers, floods have become quick and frequent in different nations.

Recent years have witnessed some of the most devastating wildfires of all times. This is because of the frequent rise of temperature in the environment.

It is observed that the duration of the season has changed greatly. In some years, winters arrive early whereas summers are late. Moreover, rains fail to appear in the allotted seasons.

The food chains have witnessed massive changes. This is because migration seasons of birds are affected due to the change in seasons. The whole food chain has seen a massive drift in recent years.

What is the Greenhouse Effect?

Greenhouse effect is the key reason for environmental concerns like climate change. This could be understood by analysing the mechanism employed inside a greenhouse. A greenhouse is a structure made completely out of glass. It houses several plants which require a high range of temperature to thrive. The solar energy absorbed through this greenhouse ensures that the temperature inside the structure is relatively higher than that of outside. The mechanism here is that the solar energy absorbed is either not reflected at all or is reflected in small amounts. This ensures that the temperature remains high for the required growth of plant species.

However, the greenhouse effect has been hindering the environmental conditions. The solar energy absorbed by the atmosphere is not reflected and is not regulated throughout the circumference.

Greenhouse Gases

• Greenhouse effect is carried out throughout the environment due to the presence of certain harmful gases. These gases are called greenhouse gases. They either exist naturally in the environment or are produced due to the unethical industrial and day to day activities.

• Methane is a commonly found greenhouse gas. It is released in the environment during the production of minerals, coals, oils, etc. it is also released during the decaying process of waste material in the landfills. Methane holds the power to create global warming potential in the environment for almost 100 years.

• Certain fluorinated gases also exist in the environment. Hydrofluorocarbon, perfluorocarbon, etc. form the family of fluorinated gases. These are released in the atmosphere due to the industrial and commercial activities practised in day to day life. Household consumption of commercial products increases the rate of the release of gas.

What Is The Cause of The Greenhouse Effect?

• The major cause of the greenhouse effect is the unlawful and hazardous activities of humans. These activities contribute to the harmful cause of greenhouse effect. Burning of fossil fuels containing carbon components is a key cause of the same. The carbon released in the air reacts with the oxygen and forms the deadly compound of carbon dioxide.

• Moreover, another key element causing the greenhouse effect is the deforestation and unethical utilisation of land. The carbon dioxide stored in trees is released in heavy amounts and adds to the risk of global warming.

• Heavy consumption of commercial appliances like air conditioners also add to the emission of greenhouse gases in the environment. Moreover, the landfills containing millions of nonrecyclable materials are burnt in the open air. This also contributes to the addition of carbon dioxide in the air.