Category: Chemistry Notes PPT

Bisulfate salts are basically the salt of the anion HSO4^–. Sodium bisulphate is the most popular bisulphate compound. This bisulphate is formed by the sodium cation and HSO4^– anion. This salt is formed by the partial neutralization of sulphuric acid by the equivalent amount of sulphuric base. This base can be either in the form of sodium hydroxide or sodium chloride most probably. Anhydrous form of sodium bisulphate is hygroscopic. Solutions of Sodium bisulfate are mostly acidic with (1 M) molarity solution of sodium sulphate having pH approximately equal to 1.

 If we talk about its properties in brief then the sodium bisulphate monohydrate has a melting point of approximately 183° C. Talking about its Cass number, then the Cass number of sodium bisulphate is 10034-88-5.

Sodium bisulphate in small amounts does not harm but if it is consumed in large amounts in the body, it can be very harmful. Sodium bisulphate is actually a dry acid.

Talking about sodium bisulfite or sodium hydrogen sulphate.

Sodium Hydrogen Sulphate (NaHSO₄) is also known as Sodium Bisulfate. It is the sodium salt (NaCl) of the bisulphate anion [ SO_{4}^{2-}].

Sodium Bisulfate is an acidic salt (acidic solution is produced after salt is dissolved in a solvent)which is produced by partial neutralization of Sulfuric acid (H2SO4)with an equivalent amount of sodium base, basically in the form of sodium hydroxide (NaOH) or sodium chloride (NaCl). The anhydrous is being hygroscopic in nature. The solutions of Sodium Bisulfate are acidic in nature with a pH value of 1 for every 1M solution. It is a white and relatively dry granulated compound. It is corrosive to metals and tissues and also is soluble in water.

What is the Structure and Type of Bonding in Sodium Bisulfate?

The structure of Sodium Bisulfate molecules is explained in the figure below. It is observed that this compound features an ionic bond (overall transfer of valence electron/electrons between atoms) amongst the negatively charged bisulphate anion (HSO4^–) and the positively charged sodium cation (Na⁺). It has a Sulphur atom bonded with one hydroxyl group (OH^– or HO^–) and three oxygen atoms.

The accurate mass and the monoisotopic mass of Sodium Bisulfate (NaHSO₄) is 119.9 g/mol. The number of hydrogen bond donors is equal to one and the number of hydrogen bond acceptors equals four.

What Are The Properties of Sodium Bisulfate?

Physical Properties: Sodium Bisulfate of NaHSO4 is usually accessible in both monohydrates (hydrates consisting of one mole of water/mole of the compound), NaHSO4.H2O, and anhydrous (dry) forms. Anhydrous NaHSO4 is a dry granulated white powder, having a density of 2.74 g/ml with a melting point of 315 °C. Whereas, monohydrate is a white-colored granulated solid having density of 1.8 g/ml with a melting point of 59 °C. Monohydrate is considered a dry acid that is appropriate for safe storage and shipping. Its water solubility is 28.5 g/100 ml (25 °C) and 100 g/100 ml (100 °C) respectively. In general, if we talk about the molecular weight of NaHSO₄ it is 120.06 g/mol of anhydrous form. The melting point of sodium bisulphate is believed to be 150°C. 

Chemical Properties: Sodium Bisulfate is highly soluble in water. Aqueous solutions of NaHSO₄ are highly acidic in nature. Chemically it is an acidic salt, rather than a usual neutral salt. This is due to the replacement of only one acidic proton of the diprotic sulfuric acid. Aggressive reactions take place with strong oxidizing agents and strong bases. It stays in stable condition under ordinary conditions but decomposes instantly when contacted to water.

Preparation of Sodium Bisulfate

There are quite a few approaches for obtaining Sodium Bisulfate (NaHSO₄):-

1. The neutralization reaction of an acid with a base resulting in the formation of salt and water. NaHSO₄ can be prepared by the reaction of sulfuric acid (H2SO4) and sodium hydroxide (NaOH), but these elements must be reacted in a specific ratio: the acid should be available in plenty as compared to the base. 

H₂SO₄ + NaOH →  NaHSO₄ + H₂O

(Reaction is carried out with concentrated sulfuric acid. Reagents react in the ratio of 1:1.)

By the reaction of 2 moles of NaOH and 1 mole of H₂SO₄, sodium sulphate Na₂SO₄ forms:

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

(the protons of H₂SO₄ are completely replaced with Na ions and complete neutralization occurs, the product is normal salt)

2. The reaction of an acid oxide with an alkali (taking oxide in abundance will result in the formation of acid salt):

NaOH + SO₃   →     NaHSO₄

If sodium hydroxide (NaOH) is taken in abundance while carrying out this reaction, normal (Na₂SO₄) salt will be formed.

3. The reaction of normal salt and an acid:

Na₂SO₄ + H₂SO₄    →       2NaHSO₄.

Some acid salts are acquired by hydrolysis (reaction with water, in which the original substance breaks down to form new compounds). NaHSO₄ cannot be acquired from sulphate by hydrolysis, since this salt is originated by the strong base NaOH. Since H₂SO₄ and Na₂SO₄ does not react with water, but only gets dissolved in it. For example, NaHCO₃ is formed by strong base NaOH and the weak acid H₂CO₃.

Uses of Sodium Bisulfate

Sodium Bisulfate falls under the class of chemical compounds known as acid salts. At the time of its production, NaHSO₄ preserves one of the hydrogen ions of a raw material (sulfuric acid), thus obtaining the acidic properties. It is this acidic quality that classifies NaHSO₄ as a general acid for industrial uses. Simultaneously, it is considered as a special acid for a few applications because of its purity. NaHSO₄ is dry and granular which is readily soluble in water and commonly used for adjusting pH in many applications. In brief in the following points you will get the knowledge of most of the uses of sodium bisulphate:

• The water in the swimming pool is usually acidic and to lower the pH of water in the swimming pool, we use sodium bisulphate.

• For metal finishing also you can use sodium bisulphate.

• In the chicken house, you are required to lower or reduce the concentration of Salmonella and for this sodium, bisulphate can be used.

• Sodium bisulphate can be used to facilitate a reaction. Thus, it is a very good catalyst.

• Sodium bisulphate can be used as a bleaching agent.

• For manufacturing papers in the paper house, you can use sodium bisulfate.

• The treatment of water in the water treatment plants can use sodium sulphate.

• Sodium sulphate can be used in paints.

• Sodium sulphate can be used in agricultural chemicals.

• For the preparation of velvet clothes, you can use sodium bisulphite.

Preservative

Sodium bisulfate is commonly used as a preservative, food additive, in meat processing, in dietary supplements, and in drugs. It is used as a food additive to make the dough rise as well as being used in meat and poultry processing. Recently it is being used in the browning prevention of fresh-cut produce. It is also used as a general-use feed additive, including companion animal food.

Swimming Pool Application

Sodium Bisulfate is used for reducing pH levels in swimming pools and spas. NaHSO₄ is the safest product for use in homes, spas, and institutional pools. Generally, 1-2 lbs. are applied in a pool of capacity 10,000 gallons which adequately reduces the pH level. After one or two hours the pH is above 7.8, the treatment is repeated until the pH level is between 7.2 and 7.6.

Metal Finishing

NaHSO₄ is the chief component for dry acid bath formulations in metal cleaning. The common formula for most of the acidic baths includes salts of fluorides (5-10%), NaHSO₄ (90-95%) along with a surfactant (a substance that reduces surface tension). The concentration is normally 3 lbs. per gallon of water. At temperatures till 170°F., this bath has the capability to clean copper, brass, steel, nickel, zinc, aluminum, titanium, magnesium, and stainless steel. Typically used are for scale removal, pickling, etching, and rust removal.

Adjuvant

Sodium Bisulfate defends agricultural spray chemicals owing to alkaline hydrolysis in spray solutions. The effectiveness of agricultural pesticides is significantly lessened when added to water having high pH. NaHSO₄ functions mainly well with glyphosate (kills unnecessary grasses) to improve their usefulness. Acidification with Sodium Bisulfate is suggested as a substitute to ammonium sulfate ((NH₄) ₂SO₄) for use with several herbicides.

Water Treatment

Sodium Bisulfate is applied as a descaler in boilers, cooling towers, and also water pipes. Sodium Bisulfate cleans and adjusts pH level. If there is a requirement for waste treatment of an alkaline nature, Sodium Bisulfatehighly is recommended.

Concrete Washout

Sodium Bisulfate reduces alkalinity in “wash out” ponds which is formed due to concrete truck cleaning. Concrete companies are potential distributors. Representatives of JonesHamilton Co. technical service can recommend pH adjustments.

Leather Tanning

Sodium Bisulfate acts as an acidifier for leather compounds when combined with quebracho tannin. It is added with fillers and other chemicals for acidifying hides used in shoe sole leather.

What are the Safety Hazards of Sodium Bisulfate?

Due to its strong acidic nature, sodium bisulfate is very irritating to the eyes and skin. At high concentrations, it can cause serious eye damage upon contact. It can cause severe diarrhea and vomiting if swallowed and is very toxic in large amounts. Sodium hydrosulfite is a toxic, corrosive, and non-combustible compound. Inhaling, swallowing or skin contact causes severe injury or leads to death. Oh heating, it liberates irritating and toxic gases. Besides all this sodium bisulphate is really hazardous for our health. As you can see it can be corrosive, toxic and a non-combustible compound as well. If you have ever inhaled, swallowed or even skin contact with this compound it can cause serious injury and in some cases, it may even cause the death of a person. This compound radiates irritating as well as toxic gases which are really dangerous.

An Overview of Sodium Nitrate – NaNO3

As you know, chemistry can be the most scoring subject in examinations if studied with little extra effort. So, here are some important notes on sodium nitrate for your convenient.

It is a chemical compound of nitrate, commonly called Chile saltpeter. The chemical formula of this compound is NaNO3. Its mineral form is again called soda niter or nitratite, nitratine. NaNO3 name is frequently used in industrial production of fertiliser, smoke bomb, pottery enamels, glass, food preservatives, pyrotechnics, etc. 

What is Sodium Nitrate?

Sodium nitrate is the chemical name for NaNO3. It is an inorganic alkali metal nitrate salt. This compound is made of one sodium cation or Na+ and one nitrate anion or NO3–. Also, NaNO3 compound name, a white coloured crystalline solid, sodium nitrate in water is extremely soluble.  

Though it is non-flammable, this powerful oxidising agent can violently react with several flammable compounds. Usually, NaNO3 on heating above 538oC can decompose explosively. 

Structure of Sodium Nitrate

To understand the answer to what is NaNO3 and how it reacts with other compounds, you need to evaluate the structure of NaNO3. Its composition defines an ionic bond of one NO3– and one Na+. You can see the sodium nitrate structure in the diagram below.

(Image to be added soon)
Moreover, you can opt for the NaNO3 Lewis structure to obtain a better understanding of the molecular arrangement. The simplified depiction of the electron structure in the outermost shell or valence shell of a molecule is termed as Lewis structure. 

By this structure, you can identify the arrangement of electrons around separate atoms inside a molecule. In this structure, electrons are represented as dots. However, for bonding electrons, a line can be used between two atoms as well. 

Here is the Lewis structure of NaNO3–

(Image to be added soon)

While studying chemistry, you should not only learn the chemical formula of sodium nitrate NaNO3 but also understand its structure. Once you know the molecular bonding and structure, you can easily memorise what is the chemical formula for sodium nitrate.

Moreover, understanding the molecular or Lewis structure is also vital to comprehend all its chemical reactions. For example, if the concept of NaNO3 structure is clear, you can be confident about the answers of how the molecules will bond in different chemical reactions.

Preparation of Sodium Nitrate 

From the above information, you can understand what is the name of NaNO3 or what is the formula for sodium nitrate. These are the most basic information about this chapter that you should know. However, now the discussion will be on sodium nitrate preparation.

Here are the chemical equations of nitric acid neutralisation by industrial synthesising. The reactions happen between sodium nitrate and sodium hydroxide, sodium carbonate, and sodium bicarbonate. 

Nonetheless, this rection with sodium hydroxide is extremely exothermic as HNO3 is powerful acid and NaOH is a powerful base.

However, sodium nitrate can be produced by replacing nitric acid with ammonium nitrate in these reactions.

NaHCO3 + NH4NO3 🡪 NH4HCO3 + NaNO3

Na2CO3 + 2 NH4NO3 🡪 (NH4)2CO3 + 2 NaNO3

NaOH + NH4NO3 🡪 NH4OH + NaNO3

Properties of Sodium Nitrate

For your upcoming examinations, you need to know more than just about NaNO3 chemical name and its preparation. It is important to identify some properties of NaNO3 for future reference.

Here is some information about the physical properties of sodium nitrate.

1. NaNO3 is solid that appears in a crystalline structure and white colour, in room temperature.

2. Its crystal structure can be categorised into two types – trigonal and rhombohedral.

3. This compound comes with a sweet odour.

4. It has a slightly bitter and saline type of taste.

5. At 25oC temperature, the water solubility of NaNo3 corresponds to 91.2 gram per 100 millilitres.

6. Sodium nitrate is also a highly ammonia soluble compound.

7. NaNO3 is also slightly soluble in methanol and ethanol.

Some Chemical Properties Of NaNO3 Are

1. After dissolving in water, NaNO3 breaks into One Na+ and one NO3–.

2. This is a highly powerful oxidising agent. Thus, with reducing agents, NaNO3 reacts violently.

3. It decomposes at high temperature and produces oxygen and nitrogen oxides. Due to this oxygen production, it can increase the fire hazard and lead to explosive decomposition.

4. During decomposition, NaNO3 emits toxic gasses like sodium oxide and nitrogen oxide.

5. The pH balance of NaNO3 aqueous solution is neutral.

Other Names of NaNO3

Beside sodium nitrate, there are several names for NaNO3. As a medical aspirant, you should know some of its synonyms as well. As said earlier, Chile saltpeter is the most popular name of this compound. Here are some other names-

Did You Know

1. The compound names of NaNO3 are Na+ or sodium cation and NO3– or nitrate anion.

2. The chemical name of NaNO3 is sodium nitrate. 

3. Chile saltpeter is nothing but sodium nitrate or NaNO3. 

Sodium Nitrate in Food

NaNO3 has been treated as preservatives in meat curing for years. Though this chemical compound does not have any antioxidant activity, it can be functional if reduced to nitrite. Sodium nitrate can majorly help in stabilising meat colour, improving texture, developing the characteristics flavour of cured meat, and diminishing antimicrobial activities. 

It can also act as metal chelators that help the formation of nitroso compounds. These chemical compounds carry antioxidant properties and form stable nitric oxides from heme proteins.

Thus, foods that contain sodium nitrate are various processed meats like ham, bacon, salami, pate, hot dog, dried fish, sausages, smoked salmon, etc. In examinations, if you get a question like what foods have sodium nitrite, hopefully, you can answer that after reading this content.

Effect of Sodium Nitrate on Plant Growth

Nitrogen is one of the most vital elements that should be present in the soil for plant growth. Thus, the application of nitrogen fertiliser can rapidly help in crop growth. During the initial stage, a visible influence of sodium nitrate on plant growth can be observed. It can act as a stimulator. However, often use of fertiliser can lead the plant to wilt. Moreover, plants can also stop growing, or the process will become slow.

So, this erroneous practice must be discredited.

Application Process of Sodium Nitrate

As sodium nitrate is completely water-soluble, and also as the soil colloids cannot absorb the nitrate ion, you may wonder how sodium nitrate should be applied. For maximum result, it must be used for initial utilisation. The major problem is the drainage of nitrate with water when it is applied to sands that have open subsoils. In these types of application, the most amount of nitrite is used easily.

Even if it is applied to clay, the quantity should not be more than what plants can utilise within a generous period of time. This way, nitrogen leaching can be minimised as well as plant root injuries due to excessive salt presence can be avoided. 

Uses of Sodium Nitrate

Due to the high water solubility and nitrogen presence, and low cost, there are several uses of sodium nitrate as fertilisers. However, there are some other uses of this compound listed below-

• By utilising NaNO3, hybrid aqua regia can be formed. These hybrids are useful to dissolve gold.

• For centuries, sodium nitrate is used as food preservatives.

• In different fireworks, it can act as an oxidiser.

• This is also regarded as one of the most effective instant cold packs.

• Sodium nitrate works as heat storage and transferrer in solar plants.

• It can also act as a substitute for potassium nitrate in gunpowder.

Thus, these are the most common uses of NaNo3 as it is one of the most cost-effective and huge sources of nitrogen. Moreover, in various rocket propellants, this compound is majorly utilised as well.

History

During the 19th century, NaNo3 was known as ‘white gold’. Chile, a South American country, fought against Peru and Bolivia to retain their territory in the desert of the Atacama, known for its rich deposits of sodium nitrate.

However, the popularity of the Haber process gradually reduced the demand for natural NaNo3. Due to the increase of synthetic NaNo3 production, the mining of natural deposits has also become obsolete.

For more extensive information about sodium nitrate, and other topics of chemistry, you can visit our website now. You can also download our app for a better learning experience.

The maximum amount of Solute that can dissolve in a known quantity of solvent at a certain temperature is its Solubility

A Solution is a Homogeneous mixture of one or more Solutes in a Solvent. Sugar cubes added to a cup of tea or coffee is a common example of a Solution. The property which helps sugar molecules to dissolve is known as Solubility. Hence, the term Solubility can be defined as a property of a substance (Solute) to dissolve in a given solvent. A Solute is any constituent which can be either solid or Liquid or gas liquified in a solvent.

 

Solubility Product

The term solubility product is generally applicable for frugally Soluble salts. It is the maximum product of the molar concentration of the ions (raised to their appropriate powers) which are produced due to dissociation of the compound.

 

At a given temperature the solubility product is constant. Lesser the value of solubility product indicates lower solubility and higher value of solubility product indicates greater solubility.

 

Solubility Definition

Solubility is a property referring to the ability for a given substance, the solute, to dissolve in a solvent.It is restrained in terms of the maximum amount of solute dissolved in a solvent at balance. The resulting solution is called a saturated solution. Certain substances are Soluble in all proportions with a given solvent, such as ethanol in water. This property is known as miscibility.Under numerous conditions, the balance solubility can be surpassed to give a so-called supersaturated solution, which is metastable.The solvent is frequently a solid, which can be a clean substance or a mixture.

 

Gas solubility in liquids involves the concept of gas dissolving in a solvent. Let us first define solubility. For any substance, solubility is the maximum amount of solute that can be dissolved in a given solvent at a particular temperature. Now our concern is gas solubility in liquids. The gas solubility in liquids is significantly affected by temperature and pressure and also by the nature of the solute and the solvent.

 

There are many gases that readily dissolve in water, while there are gases that do not dissolve in water under normal conditions. Oxygen is just sparingly Soluble in water whereas HCl or ammonia readily dissolves in water.

 

Other Types of Solubility

Water is known as a universal solvent as it dissolves almost every solute except for a few. A few factors can influence the solubility of a substance.

 

Solubility is the new bond formation amongst the solute molecules and solvent molecules. In terms of quantity, solubility is the maximum concentration of solute that dissolves in a known concentration of solvent at a given temperature. Based on the concentration of solute dissolves in a solvent, solutes are categorized into highly Soluble, sparingly Soluble or inSoluble. If a concentration of 0.1 g or more of a solute can be dissolved in a 100ml solvent, it is said to be Soluble. While a concentration below 0.1 g is dissolved in the solvent is known to be sparingly Soluble. Thus, it is known that solubility is a quantitative expression and articulated by the unit gram/litre (g/L).

 

Based on solubility, different types of solution can be obtained. A saturated solution is a solution where a given amount of solute is completely Soluble in a solvent at a given temperature. On the other hand, a supersaturated solution is those where solute starts salting out or precipitates after a particular concentration is dissolved at the same temperature.

 

Factors Affecting Solubility:

The solubility of a substance hinges on the physical and chemical properties of that element. In addition to this, there are a few conditions which can manipulate it. Temperature, pressure and the kind of bond and forces in between the particles are a few among them.

By changing the temperature we can increase the Soluble property of a solute. Generally, water dissolves solutes at 20° C or 100° C. Sparingly Soluble solid or liquid substances can be liquified completely by raising the temperature. But in the case of gaseous substances, temperature inversely influences solubility i.e. as the temperature increases gases expand and escape from their solvent.

Like dissolves in like. The type of intermolecular forces and bonds vary among each molecule. The chances of solubility between two dissimilar elements are more challenging than the like substances. For example, water is a polar solvent where a polar solute like ethanol is easily Soluble.

Gaseous substances are much more influenced than solids and liquids by pressure. When the partial pressure of gas rises, the chance of its solubility is also hiked. A soda bottle is an example of where CO2 is bottled under high pressure.

It has been observed that solid solubility depends on the nature of the solute as well as the solvent. We frequently see that substances like sugar, common salt (NaCl), etc quickly dissolve in water while substances like naphthalene do not dissolve in water.

Reactions are the result of chemical compositions. To make the reaction possible, reactants are necessary. They collage together to form new products. Every reactant absorbs energy during its chemical collages. 

Some of the reactions absorb energy, whereas others take part in the evolution of energy. We know that the change in enthalpy is obvious in many chemical reactions. Without it, the process is incomplete. 

You can describe the change of enthalpy as the enthalpy of reaction. This article is all about how you should describe standard enthalpy of formation, standard enthalpy of combustion, and enthalpy of bond dissociation.

Define Enthalpy of Formation

We can define standard enthalpy of formation just by mentioning the enthalpy change. It is possible when a compound’s one mole is created from its associated elements within their stable state of aggregation state. 

The stable state of aggregation is considered when the temperature is at 298.15 K, and atmospheric pressure is at 1 atm.

What Is the Enthalpy of Formation?

The enthalpy of formation definition can be understandable with the examples. Let’s take an example to elaborate it briefly. We can consider the formation of methane from hydrogen and carbon:

C(graphite, s) + 2H₂(g)→ CH₄(g); Δ_fH^o = – 74.81kJmol^-1

Can you answer What Is Standard Enthalpy Of Formation? Enthalpy of formation comes under the category of a special case of standard enthalpy of reaction. In this process, two or more reactants are involved. They combine together to create one mole of the product. 

The example of the formation of hydrogen bromide from bromine and hydrogen can be the best example. Here is the expression:

H₂(g)  + Br₂(l) ⟶ 2HBr(g) ; Δ_rH^o = – 72.81kJmol^-1

As per the above expressions, it is clear that two moles of hydrogen bromide are available. Therefore, standard enthalpy of formation can be taken as the enthalpy of reaction, and not as the enthalpy of formation of hydrogen bromide.

We can say that 

Δ_fH^o = 2 Δ_rH^o

Δ_fH^o =  Enthalpy of formation

Δ_rH^o = Enthalpy of reaction

Enthalpy of Combustion

We can say that the enthalpy of combustion is only possible when one mole of a compound is burnt completely to give rise to oxygen at the end. All of the processes are taken into consideration when all the reactants and products are in the standard state and under standard conditions (1 bar pressure and 298K).

For example:

H₂(g) + 1/2 O₂(g) ➝ H₂O(l) ; Δ_cH^o = – 286 kJmol^-1

C₄H₁₀(g) + 13/2 O₂(g) ➝4CO₂(g) + 5H₂O(l) ;  Δ_cH^o = -2658 kJmol^-1

Standard enthalpy of combustion is a positive value as combustion is always exothermic. When a chemical substance comes under the process of combustion, it generates energy to outside. So, the change in enthalpy for the exothermic reactions is negative.

However, in the convention process, the molar heat of combustion (also molar enthalpy of combustion) is considered as a positive value.

We can calculate the enthalpy of combustion with ease. The process is very simple. We do it by calculating the difference between the mass of the fuel before the boiled water and the mass of the fuel. 

The workout energy of a substance can be given as 1 mole. The unit that stands to show the measurement of enthalpy of combustion is known as Joule per mole (or Kilojoule per mole).

If you need your answer in KJ (kilojoule) format, you just need to devise the result by 1000. 

Bond Dissociation Enthalphy

This is a type of change in enthalpy where one mole of covalent bonds of a gaseous compound is taken apart to manufacture different gaseous phase products.

In general, the enthalpy of bond dissociation is always different from the bond enthalpy values. In a molecule, it is the average of some of all the bond dissociation energy.

A few examples of diatomic molecules that come under the bond dissociation enthalpy process:

• Cl₂(g) ➝2Cl(g)

• Δ_Cl-ClH^o = 242kJmol^-1

What is Benzene?

Benzene is a colourless, flammable chemical used for various purposes. It is a highly toxic solution and carcinogenic (cancer causing), which has limited its use in applications today compared to the nineteenth century when it was invented. 

It is generally used as a precursor in the manufacturing of complex compounds like petroleum products. One of its distinct properties is the odour, which is what gives petroleum products like petrol, kerosene, and natural gas their signature smell. This smell is important because it allows people to identify if there’s a leakage, whether in a factory capacity or a household.

Benzene is one of the most widely used chemicals in the world, with applications ranging from detergents to use in rubber manufacturing. It is also found on various products that we used to use on a daily basis. Some of these products are listed below. However, it should be noted that non-industrial usage has been limited due to its carcinogenic properties.

• Glue

• Detergents

• Colour dyes

• Plastic

• Gasoline

Benzene is made up of six atoms of carbon and six atoms of hydrogen. Therefore, its chemical formula is C6H6. Due to this property, it is also known as a hydrocarbon. It has alternating

double bonds and that’s why classified as an aromatic hydrocarbon. It is also a natural ingredient in crude oil.

Structure of Benzene

 

As shown in the above representation of Benzene (three forms), it is made up of six atoms of carbon and hydrogen each. Although it is distant from its parents, alkane and hexane, the pi-bond characteristics make it a preferred ingredient in chemical compositions where a pungent smell is a required property.

As shown in the eight representation in the diagram below, Benzene is often depicted with a circle inside a hexagon to showcase its nature of bonding, which is stable.

However, in Basic Chemistry, There are Three Ways of Drawing the Structure of Benzene. They are:

1. Labelling of carbon and hydrogen and forming a bond between them. The shape is hexagonal. This representation shows all the twelve atoms involved in the formation

2. A hexagonal structure where each edge of the hexagon corresponds to a carbon atom. Hydrogen atoms are omitted. Instead, the alternating bonds are shown

3. A circle is drawn inside a hexagonal structure. This shows the stability of the chemical solution.

History of Benzene

English scientist Michael Faraday is credited with identifying benzene in 1825, which was in the form of an oily residue during an experiment involving the production of illuminating gas. Experiments in production began in 1833 through a combination of benzoic acid and lime. After a series of more experiments and identifications in the nineteenth century,

benzene became a common chemical for use in petroleum by the early twentieth century.

It had been used as an aftershave, decaffeination, and degreasing. Since all of these involved its contact with humans, and since it was soon found that benzene has carcinogenic properties, its usage was soon stopped. Over the decades, lesser toxic solutions have been identified as alternatives for those purposes.

However, this has not limited its use in industrial applications such as the production of petroleum and plastic products.

Early Applications of Benzene

As stated above, Benzene was used in various applications as a catalyst. Here are some of those applications, most of which were recalled when it was found that the chemical solution is extremely toxic in nature.

• As an after-shave lotion because of its smell (this was later replaced by alum)

• As an industrial solvent to degrease metal; it was later replaced by toluene which is not carcinogenic

For coffee decaffeination and the subsequent production of Sanka, a popular brand of decaffeinated coffee that was sold in the roaring twenties; it was later recalled due to the toxicity

• For the production of consumer products like rubber cement, spot removers, paint add-on, and detergent

Although some of these applications still find a place for benzene, many of them have been discontinued. This is supported by the identification of cheaper and healthier alternatives.

Modern Applications of Benzene

Although it is a harmful compound for humans, it is still a widely used solution for some of these applications:

• Production of other chemicals like cumene and nitrobenzene where two or more compounds (one of which is benzene) are combined to form newer solutions

• Nylon fibres; the processing of textiles and plastics

• Lubricants, rubber products, drugs, explosives, and pesticides; here the usage is minimal and in most cases is only used as a catalyst

Exposure to Benzene

As mentioned above, Benzene is a highly toxic substance that can cause cancer. Its exposure can have serious effects on humans as noted below:

• Anaemia

• Leukaemia

• Multiple myeloma

If consumed, it can lead to rapid metabolism and may damage the digestive system. This can be fatal if not treated immediately

Due to these effects, there are limitations to the use of Benzene in almost all industries. Governments and organizations have come together to place these regulations so that workers involved in their production or usage do not fall prey to its harmful effects.

Occurrence of Benzene

The primary source of Benzene is produced out of petrochemicals, where it is a by-product. It is the only way to mass-produce benzene as all other natural sources produce it as traces.

Other such sources are coal, natural oil, and coke production. Countries like China, the United States, and regions of the Middle East and Africa are expanding on the production of Benzene due to its increasing demand.

Benzene Alternatives

Toluene and Xylene are two compounds that have replaced Benzene in almost all modern applications. However, this has only limited its usage. Benzene is still a widely used chemical solution.

Sulfur trioxide is described as a chemical compound. Sulfur trioxide formula is given as SO3. Sulfur trioxide is available in a number of modifications that varies in the form of molecular species and crystalline. It is colourless and forms liquid fumes in the air at ambient conditions. It is also a strong oxidising agent and a highly reactive substance, and it acts as a fire hazard. Thermodynamically, it is an unstable compound with respect to selenium dioxide.

The other names of sulfur trioxide can be given as sulfuric anhydride.

Structure of Sulphur Trioxide

Properties of Sulfur Trioxide – SO3

Let us look at the important properties of sulfur trioxide given as follows:

Physical Properties of Sulfur Trioxide – SO3

Chemical Properties of Sulfur Trioxide – SO3

SO3 + H2O → H2SO4

SO3 + NaOH → NaHSO4

Uses of Sulfur Trioxide – SO3

• This can be used as a bleaching agent to remove the residual hydrogen peroxide, or as a digesting agent for pulp separation from lignin.

• We can use it as a catalyst in the sulfur dioxide oxidation reaction to sulfur trioxide.

• Strong inorganic acid mists that contain sulfuric acid, is used either in the industry or in the production of the commercial product.

• It is also used as an important reagent in sulfonation reactions.

• It can be used in the manufacturing of solar energy devices and photoelectric cells.

Molecular Structure and Bonding

• SO3, in its gaseous form, is a D3h symmetry trigonal planar molecule, similarly predicted by VSEPR theory. So, it is said that SO3 belongs to the D3h point group.

• In the aspect of electron-counting formalism, the sulfur atom contains an oxidation state of +6 and with a formal charge of 0. The Lewis structure holds one S=O double bond and two S–O dative bonds without utilising the d-orbitals.

• The gaseous sulfur trioxide’s electrical dipole moment is given as zero. This is a consequence of the angle of 120° between the S-O bonds.

Preparation

Let us look at the preparation of sulfur trioxide using various methods as follows:

In the Atmosphere

The direct oxidation of the sulfur dioxide to sulfur trioxide in air, and this reaction can be given as follows:

SO2 + ​1⁄2O2 = SO3  ΔH=-198.4

The above reaction does take place, but this proceeds very slowly.

In the Laboratory

Sulfur trioxide is prepared in the chemical laboratory using the two-stage pyrolysis of the sodium bisulfate compound. The sodium pyrosulfate is given as an intermediate product:

At dehydration 315 °C, the chemical reaction is given as:

2 NaHSO4 → Na2S2O7 + H2O

Cracking at a temperature of 460 °C, the reaction can be given as:

Na2S2O7 → Na2SO4 + SO3

In contrast, KHSO4 compounds do not undergo a similar reaction.

It can also be prepared by adding the concentrated sulfuric acid to phosphorus pentoxide.

In Industry

SO3 can be prepared industrially by the contact process. Sulfur dioxide, which in turn can be produced by the burning of iron pyrite (a sulfide ore of iron) or sulfur. After being purified by the electrostatic precipitation, the SO2 compound is then oxidised by atmospheric oxygen at a temperature between 400 and 600 °C over a catalyst. A typical catalyst contains vanadium pentoxide (V2O5) activated wi
th the potassium oxide K2O on silica or kieselguhr support. Also, platinum works very well, but is much more expensive and is poisoned (which is rendered ineffective) much more easily by the impurities.

The majority sulfur trioxide compound, which is made in this way is converted into the sulfuric acid, but not by the direct addition of water, where it forms a fine mist, but by absorption in concentrated sulfuric acid and dilution with water of the formed oleum.

Once, it was industrially produced by heating the calcium sulfate with silica.

Applications

Sulfur trioxide is defined as an essential reagent in the sulfonation reactions. These processes afford dyes, pharmaceuticals, and detergents. Sulfur trioxide can be generated in situ from the sulfuric acid, or it can be used as a solution in the acid.

Safety

Sulfur trioxide, along with being a strong oxidising agent, will cause serious burns on both ingestion and inhalation because it is highly hygroscopic and corrosive in nature. SO3 compounds should be handled with extreme care because it reacts violently with water and also forms highly corrosive sulfuric acid. Also, it should be kept away from the organic material because of its strong dehydrating nature and its ability to react violently with such types of materials.