Category: Chemistry Notes PPT

A solution is a homogeneous mixture of two or more two substances whose particle size is 0.1nm -1nm. Homogeneous means that the components of the mixture form a single phase. 

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Example of Solutions

You must have seen many types of solutions in general such as soda water, sharbat, salt solution, etc. You would have seen brass utensils as well which are also homogeneous solutions of solid into solid. We can prepare solutions of solid-liquid, solid-solid, solid-gas, liquid-solid, liquid-liquid, gas-solid, gas-liquid, and gas-gas. Gasoline, alloys, air, starch solution, etc. are examples of solutions. 

Solutions Consist of -Solute and Solvent

Solute

The substance which is being dissolved in the solvent to form a solution is called a solute. It is present in lesser quantities than solvent in the solution.

Solvent

The component of a solution in which solute is being dissolved is called a solvent. It is present in more quantities than solute in solution. 

Example

If we take a solution of saltwater. Then in this solution salt is solute and water is a solvent as salt is being dissolved in water and salt is present in lesser quantity than water in the solution. 

Thus, we can say solvent forms a major proportion of the solution. 

Examples of Solutions 

Sugar-water, salt solution, brass, alloys, alcohol in water, aerosol, air, aerated drinks such as Coca-Cola, etc. are examples of solutions. When we work with chemistry, we generally prepare many types of solutions such as copper in water, iodine in alcohol, etc. 

Properties of a Solution 

A solution possesses the following properties – 

• A solution is a homogeneous mixture. 

• The constituent particles of a solution are smaller than 10-9 meters in diameter. 

• Constituent particles of a solution cannot be seen by naked eyes. 

• Solutions do not scatter a beam of light passing through it. So, the path of the light beam is not visible in solutions. 

• Solute particles cannot be separated by filtration. 

• Solute or solvent particles do not settle down when left undisturbed. 

• Solutions are stable at a given temperature. 

Types of Solutions Based on Quantity of Solute

Solutions can be divided into the following types of the basis of the quantity of solute in a solution – 

• Unsaturated solution

• Saturated solution

• Supersaturated solution

Unsaturated Solution

The solution in which we can add more solute at a given temperature is called an unsaturated solution. 

Saturated Solution

The solution in which we cannot dissolve more solute in the solvent at a given temperature is called a saturated solution. 

Supersaturated Solution 

The saturated solution in which we add more solute by raising the temperature or pressure is called a supersaturated solution. In these solutions generally, crystals start forming. 

Types of Solutions Based on the amount of solvent added

• Concentrated solution

• Dilute solution

Concentrated Solution 

The solution in which solute is present in large quantities is called a concentrated solution. 

Dilute Solution 

It has a very small amount of solute in a large quantity of solvent. 

Expressing Concentrations of Solutions 

The concentration of a solution can be expressed quantitatively and qualitatively. Qualitatively it can be expressed as a dilute solution or concentration solution. Quantitatively it can be expressed by mass percentage, volume percentage, parts per million, etc. 

Mass Percentage (w/w) 

Mass Percentage of a Component = Mass of the Component in Solution/Total mass of the Solution x 100

Volume Percentage (V/V)

Volume Percentage of a Component = The volume of the Component / Total Volume of the Solution x 100

Mass by Volume Percentage (w/V) 

Mass by Volume Percentage = Mass of Solute Dissolved in 100mL of the Solution.

Parts per Million (ppm)

Parts Per Million = Number of Parts of the Component / Total Number of Parts of all Components of the Solution x 10^6

Mole Fraction (x)

Mole Fraction of a Component = Number of Moles of the Component / Total Number of Moles of all Components of the Solution

 

Molarity (M) – Number of Moles of Solute Dissolved in One Liter of Solution. 

Molarity =  Moles of Solute / Volume of Solution in Liter

Molality (m) – Number of Moles of Solute in One KG of the Solvent. 

Molality =  Moles of Solute / Mass of Solvent in Kg

Solubility 

The solubility of a substance is its maximum amount that can be dissolved in a specified amount of solvent at a specific temperature. 

Factors that Affect the Solubility of a Substance

• Nature of solute 

• Nature of solvent 

• Temperature 

• Pressure 

Solubility of a Solid in a Liquid 

Polar solutes get dissolved in the polar solvents while non – polar solutes get dissolved in the non – polar solvents. It means all solids do not get dissolved in all types of liquids. Polar solid compounds will dissolve in polar liquid solvents while non – polar solid compounds will dissolve in non – polar liquid solvents.  

Le Chathelier-s Principal

The solubility of a solid into a suitable liquid is affected by temperature changes. Dynamic equilibrium in these types of solutions must follow Le Chatelier’s principle. 

• For a nearly saturated solution, the dissolution process is endothermic (∆H > 0). In this condition, the solubility increases with an increase in temperature. 

• For the exothermic process (∆H < 0), the solubility decreases with an increase in temperature. 

Solids and liquids are incompressible or very lightly compressible, so they are almost remaining unaffected by changes in pressure. That’s why the solubility of a solid in a liquid remains unaffected by pressure. 

Solubility of a Gas in a Liquid 

The solubility of a gas in a liquid gets greatly affected by pressure and temperature. 

Henry’s Law

Henry’s law was given by English Chemist William Henry who first formulated the quantitative relation between pressure and solubility of a gas in a solvent. The law states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution.’

Dalton proved that the solubility of a gas in a liquid solution is a function of the partial pressure of the gas. The mole fraction of gas in the solution is proportional to the partial pressure of the gas over the solution. 

Another form of Henry’s law

Another form of Henry’s law states that ‘the partial pressure of the gas in the vapor phase (p) is proportional to the mole fraction of the gas (x) in the solution.’ It can also be expressed as –

p = KH x

where p = partial pressure of the gas, KH = Henry’s constant, x = mole fraction of the gas 

At a given pressure if the value of KH increases for various gasses then their solubility decreases accordingly. 

Applications of Henry’s law 

• It is applied in the production of carbonated beverages to increase the solubility of carbon dioxide gas in beverages. 

• People who live in high altitudes have a low concentration of oxygen in their blood and feel weak. This condition is called hypoxia. It is observed in the climbers as well who climb up to high altitudes. 

• When scuba divers go underwater, they breathe air at high pressure. Increased pressure increases the solubility of gasses in the blood. High concentrations of nitrogen and other gasses can be lethal. 

• Dissolution is an exothermic process, so the solubility decreases with an increase in temperature. 

Raoult’s Law 

It was given by French Chemist Francois Marte Raoult in 1886. Raoult’s law states that for a solution of volatile liquids, the partial vapor pressure of each component of the solution is directly proportional to its mole fraction present in the solution.

If we take a binary solution of two volatile liquids and those two components are denoted by components A and B. Then, for component A –

PA ∝ xA

pA = pA° xA

Where PA = partial vapor pressure of the component of A, xA = mole fraction of component A, pA° = vapor pressure of the pure component A at the same temperature. 

For component B –

pB = pB°  xB

Where PB = partial vapor pressure of the component of B, xB = mole fraction of component B, PB° = vapor pressure of the pure component B at the same temperature. 

Total Pressure

According to Dalton’s law of partial pressures, the total pressure (ptotal) over the solution phase in the container will be the sum of the partial pressures of the components of the solution. So, it can be written as –

Ptotal  = pA + pB

On substituting the values of pA and pB –

Ptotal = pA° xA + pB° xB

Ptotal = (1 – xB) pA° + pB° xB

Ptotal = pA° + (pB° – pA°)xB

Following Conclusions can be Drawn from the Above Equation 

• Total vapor pressure over the solution can be related to the mole fraction of any one component of the solution. 

• Total vapor pressure over the solution varies linearly with the mole fraction of component B. 

• Depending on the vapor pressures of the pure components A and B, total vapor pressure over the solution decreases or increases with the increase of the mole fraction of component A.

Raoult’s Law can Also be Stated as Follows 

The partial pressure of each volatile component (or gas) in the solution is directly proportional to its mole fraction. 

Based on Raoult’s law, the liquid-liquid solution can be classified into the following two types –

Ideal Solutions

Those solutions which obey Raoult’s law over the entire range of concentration are known as ideal solutions. For ideal solutions – 

∆mixH = 0

∆mixV = 0

Non – Ideal Solution 

Those solutions which do not obey Raoult’s law over the entire range of concentration are known as non – ideal solutions. The vapor pressure of the non – ideal solution is either higher or lower than that predicted by Raoult’s law. If it’s higher than that predicted by Raoult’s law then, the solution exhibits positive deviation. If it’s lower, then the solution exhibits negative deviation from Raoult’s law. 

The solution shows positive deviation due to weaker intermolecular interactions or forces between solute-solvent molecules than solute – solute and solvent – solvent molecules. This weaker interaction increases the vapor pressure and results in positive deviation than Raoult’s Law. 

The solution shows negative deviation due to weaker intermolecular interactions or forces between solute – solute and solvent – solvent than solute-solvent molecules. This weaker interaction decreases the vapor pressure and results in a positive deviation than Raoult’s Law. 

• When only solvent molecules are volatile and present in the vapor phase (solute molecules are non – volatile) then only solvent molecules contribute to vapor pressure. If p1 is the vapor pressure of the solvent, x1 is its mole fraction and p1° is its vapor pressure in the pure state, then according to Raoult’s law –

P1 ∝ x1

As the proportionality constant is equal to the vapor pressure of solvent at its pure state. So, we can write –

P1 = x1 p1°

Colligative Properties 

Those properties which depend on the number of solute particles irrespective of their nature relative to the total number of particles present in the solution are called colligative properties. 

Relative Lowering of Vapor Pressure 

Raoult established that lowering of vapor pressure does not depend on the identity of solute particles; instead , it only depends on the concentration of solute particles. We can write –

P1 = x1 p1°

The Vapor pressure of the pure solvent will be more than that of the solvent. So, we can write change in vapor pressure as follows –

∆p1 = p1°  – p1 

= p1° – p1°  x1

= p1° (1 – x1)

As we know x2 = 1 – x1 so, we can write –

∆p1 = x2
p1°

If a solution contains many non – volatile solutes, then the lowering of the vapor pressure depends on the sum of mole fraction of different solutes. So, the above equation can be written as –

∆p1/p1° = (p1°- p1)/p1° = x2 ———(1)

In the above equation, the left-hand side equation is called relative lowering of vapor pressure which is equal to the mole fraction of the solute. 

As x2 = n2(n1+n2)so, the equation (1) can be written as follows –

(p1°- p1)/p1° = n2(n1+n2)

n1 = number of moles of solvent in the solution , n2 = number of moles of solute in the solution 

For a Highly Diluted Solution

For a highly diluted solution, n1 > > n2, so n2 can be neglected as it’s a very small value. Thus, we can write –

(p1°- p1)/p1° = n2/n1

As we know number of moles = mass/molar mass so, we can write –

(p1°- p1)/p1° = (w2/M2)/(w1/M1)

(p1°- p1)/p1° = (w2/M2) x (M1/w1)

Where w1 and M1 are the mass and molar mass of solute while w2 and M2 are the mass and molar mass of solute. 

Elevation of Boiling Point 

Elevation of boiling point also depends only on the number of solute particles instead of the nature of the solute particles. 

If the boiling point of the pure solvent is Tb° and the boiling point of solution is Tb. Elevation of boiling point will be –

∆Tb = Tb – Tb° 

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According to the results of the experiments, for dilute solutions, the elevation of the boiling point is directly proportional to the molal concentration of the solute in a solution.  Thus, we can write –

∆Tb  ∝ m 

On removing the proportionality –

∆Tb = Kbxm

Where, m = molality, Kb = Boiling point elevation constant or molal elevation constant or Ebullioscopic constant. Its unit is K kg/ mol.

If w2 and M2 are the mass and molar mass of solute which are dissolved in the w1 gram of solvent. 

m = (w2/M2)/(w1/1000) = (1000 x w2)/(M2 x w1)

∆Tb = (Kb x 1000 x w2)/(M2 x w1)

M2 = (Kb x 1000 x w2)/(∆Tbx w1)

Depression of Freezing Point 

The solution shows depression of freezing point compared to the pure solvent. 

Freezing Point 

The freezing point can be defined as the temperature at which the vapor pressure of the substance in its liquid phase is equal to its vapor pressure in the solid phase.

When we add some non – volatile solids to the solvent, its vapor pressure decreases (Raoult’s law). Due to decrease in vapor pressure, it becomes equal to solid at lower temperature. Therefore, the freezing point of the solvent decreases.  

Depression in Freezing Point

∆Tf= Tf* – Tf 

Where Tf* = freezing point of pure solvent, Tf = freezing point of the solvent when a non – volatile solute is dissolved in it.

Depression of freezing point for dilute solution is directly proportional to molality of the solution. It can be expressed as –

∆Tf ∝ m  

∆Tf = Kf m

Where, ∆Tf = depression of freezing point, m = molality, Kf = Freezing point depression constant or molal depression constant or cryoscopic constant

If w2 and M2 are the mass and molar mass of solute which are dissolved in the w1 gram of solvent. 

m = (w2/M2)/(w1/1000) = (1000 x w2)/(M2 x w1)

∆Tf = (Kf x 1000 x w2)/(M2 x w1)

M2 = (Kf x 1000 x w2)/(∆Tfx w1)

Osmosis and Osmotic Pressure 

The process of movement of the solvent across a semipermeable membrane towards a higher concentration of solute is called osmosis. Osmotic pressure is the minimum pressure required or applied to a solution to halt the flow of its pure solvent across a semipermeable membrane. Osmotic pressure is also a colligative property. It depends on the concentration of the solute in the solution. It is expressed as follows – 

π = iCRT 

Where, π = osmotic pressure 

i = van’t Hoff factor

C = molar concentration of the solute in the solution 

R = universal gas constant 

T = temperature 

When the pressure is applied more than that of osmotic pressure, then pure solvent starts flowing out of the solution through the semipermeable membrane. This phenomenon is called reverse osmosis. 

Experimental values of molar masses sometimes differ from the theoretical values of molecular masses (calculated from the colligative properties of solutions). These values are known as abnormal molar masses. 

Conclusion

This ends our coverage on the summary of the unit “Solutions”. We hope you enjoyed learning and were able to grasp the concepts. You can get separate articles as well on various subtopics of this unit such as characteristics of Types of solutions, Raoult’s Law etc. on website. We hope after reading this article you will be able to solve problems based on the topic. We have already provided detailed study notes or revision notes for this unit, which you can easily download by registering yourself on the website. Here in this article, we have discussed the unit in a summarized way with an emphasis on important topics of the unit.  If you are looking for solutions to NCERT Textbook problems based on this topic, then log on to website or download Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests, and much more

A scientist named Chevreul M.E. initially discovered the Stearic Acid formula (18 carbon atoms) in his fat studies in 1823. Stearic Acid comes after the Grecian term stéar, which means fat (also known as beef fat). It is a long-chain fatty acid (LCFA) with 14 to 18 carbon atoms that is a saturated fatty acid (no C=C double bonds). But, what is Stearic Acid? Stearic Acid is a sticky, whitish substance with a moderate odor that hovers on the surface of liquid naturally. Stearic Acid is found in vegetable and animal fats, with shea butter and cocoa butter being the most common forms. Stearic Acid in cosmetics and plastics, as well as softened plastics and stiffening detergents, are often used. Here you will read about the melting point of Stearic Acid, Stearic Acids in cosmetics, and what is Stearic Acid.

Stearic Acid Formula

As seen in the diagram below, Stearic Acid has an 18-carbon backbone and a straight-chain Stearic Acid structure.

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The above diagram represents the Stearic Acid formula and Stearic Acid structure. 

Properties of Stearic Acid Structure

Production of Stearic Acid

It is made of oils and properties of fatty acids by the saponification of triglycerides with heated liquid at a heat of around 100 degrees Celsius. The resulting solution is distilled. The most commonly available octadecanoic acid is a blend of palmitic and Stearic Acids.

Stereophonic acid has more animal fat than vegetable fat in terms of oils and fats. There are a few outliers, such as shea butter and cocoa butter, which contain roughly 28–45 percent Stearic Acid. It possesses the properties of fatty acids.  It’s also made biosynthetically from carbs, thanks to the fatty acid machinery. In other words, it is a fatty acid example.

Stearic Acid Use

Since Stearic Acid possesses a bifunctional nature, a polar head unit that may be connected to metallic activities, it offers a wide range of applications. Stearic Acid’s apolar branch is also soluble and contains organic substances. As a result of this mixture, Stearic Acid is used as a detergent and relaxing ingredient in a variety of applications.

As well as the usage of Stearic Acid in all of such goods is due to the fact that it is reasonably affordable, inactive, and non-toxic. Furthermore, since Stearic Acid undergoes the normal interactions of saturated carboxylic acids, it is also employed in beverages. Because Stearic Acid resists oxidation, metals may be held for a prolonged period.

Here is a list of commodities that require the use of Stearic Acid: 

• For the pearly effect, 

• as a food component in detergents in soaps, cosmetics, and cleaners

• As a fantastic softening and releasing agent

• Like a negative plate additive in lead-acid battery production

• Hardening candies in sugar or corn syrup

• Gums for chewing

• In order to create vitamins and tablets

• Candles are made from fatty acid is Stearic Acid.

• As an antioxidant coating for aluminum and iron powder.

The above products are all fatty acid examples.

Stearic Acid Safety

Stearic Acid is a saturated fat that is employed in a variety of diets. And, when contrasted to carbohydrates and other saturated fats. Stearic Acid is far better to consume since it decreases LDL (low-density lipoproteins) cholesterol, also known as nasty cholesterol. Stearic Acid has been shown to be safe in several studies. Animal fats are the predominant dietary source of this acid, with botanical fats providing just a minor contribution (Exceptions: coconut, cocoa butter, palm kernel oil ). Similarly, there is no evidence that Stearic Acid consumption causes heart disease and does not affect a person’s blood lipid profile during consumption.

Fun Facts

“Although Stearic Acid is utilized in a variety of foods, it is present in nature in diluted levels. However, if Stearic Acid and magnesium combine, magnesium stearate is created, which is toxic and can cause a variety of negative effects if ingested. This chemical molecule is also flammable and heats up freely, causing irritation to the respiratory organs and skin.”

“The melting point of Stearic Acid is so high because it is a saturated fatty acid”.

The name “atom” is derived from the Greek word “a-tomio,” which means “uncuttable” or “non-divisible.” For the longest period, scientists assumed that atoms were indestructible. 

However, some scientists discovered in the early twentieth century that atoms may be broken down further into smaller components such as electrons, protons, and neutrons. Subatomic particles are what they’re called.

Discovery

The rules of conservation of mass, constant composition, and various proportions were all satisfactorily explained by Dalton’s atomic theory. 

However, it was unable to account for certain other facts, such as the creation of electricity on rubbing glass or ebonite when silk or fur was used. 

These findings paved the way for the discovery of subatomic particles in the twentieth century. Let’s take a look at how the three subatomic particles were discovered.

Discovery of Electron

Electrons are subatomic particles. It spins around an atom’s nucleus. When electrons are lost or gained from an atom, ions are created. Chemical bonding occurs when electrons from different atoms join together. A few points about the discovery of electrons and their properties are listed below:

• J. Thompson is credited with discovering electrons since he was the first to precisely calculate an electron’s mass and charge.

• All elements have an equal number of electrons and protons in their atoms.

• When compared to the mass of a proton, the mass of an electron is insignificant. Its mass is discovered to be 1/1837 times that of a proton.

• An electron has a charge of -1.602 * 10-19 Coulombs.

• Electrons are negatively charged subatomic particles.

Discovery of Proton

Positively charged particles, sometimes known as canal rays, were discovered as a result of the cathode ray tube experiment. The following are their characteristics:

• The charge-to-mass ratio of these particles varies depending on the gas they come from.

• A multiple of the fundamental unit of electrical charge is carried by some positively charged particles.

• In an electrical or magnetic environment, these particles behave in the opposite way as cathode rays.

In 1919, this was characterised and the lightest and smallest positively charged particle made from hydrogen came into existence known as Proton. 

Discovery of Neutron

Later on, scientists found an electrically neutral atom component. Chadwick, a scientist, did an experiment in which he bombarded a thin sheet of beryllium with particles in 1932. He saw the emission of electrically neutral particles that were slightly heavier than protons. As a result, these particles were given the name neutrons.

Acids are those substances that release hydrogen or hydronium ions when dissolved in their solutions. Acids can also be defined as those substances which donate a proton. Sulphuric Acid is a strong mineral acid, which is represented by the chemical formula H2SO4. Sulphuric Acid is also known as the king of chemicals due to its immense uses in various industries, especially heavy industries. It is also called matting acid and the oil of vitriol. In the eighteenth century, Sulphuric Acid was produced from green vitriol. The Sulphuric Acid thus developed has an oily look. So, it was then named the oil of vitriol.

 

Sulfuric acid is a mineral acid whose molecular formula contains one sulphur atom, four oxygen atoms with two hydrogen atoms attached directly to two of the oxygen atoms forming the -OH group, hence forming the chemical formula of sulfuric acid is H2SO4. 

It is a colourless, odourless and highly corrosive substance having great commercial importance and is used in most industries. Sulfuric acid is an oily liquid that is inherently vicious as it is highly soluble in water and is an acid rain component as well. 

It is also used as a rust preventive compound for steel and also in large quantities by metal manufacturers. However, sulfuric acid is a dangerous and toxic chemical that can cause inflammation and burns in the airways, nose and throat if inhaled. 

H2SO4 Chemical Name

The chemical name of H2SO4 is hydrogen sulphate or di-hydrogen sulphate. It contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen. It has an atomicity of seven.

 

Hydrogen sulphate is basically an ionic bond. The two ions participating in this bond are hydrogen ion (cation) and sulphate ion (anion). 

 

H2SO4 Structure

The Sulphuric Acid structure can be described as follows: –

 

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Properties of Sulphuric Acid 

• Strong Acid: Completely dissociates into ions in its aqueous solution

• Oxidising Agent: It tends to oxidise other substances in a reaction by donating its oxygen atoms. In the following reactions, it oxidises carbon and sulphur. 

2H2SO4 + C —-> 2H2O + 2SO2 + CO2 

2H2SO4 + S —-> 2H2O + 3SO2

• Basicity: The basicity of an acid is the number of hydrogen ions it releases per molecule. Sulphuric Acid is a dibasic acid and releases two hydrogen ions per molecule.

• Dehydrating Agent: Sulphuric Acid has hygroscopic properties, which means that it can attract and retain moisture from its environment. This property makes it a good dehydrating agent as it can take up and retain moisture from the surroundings and keep them dry. 

• It has a high boiling point of 337 °C and a melting point of 10 °C. 

• It turns blue litmus red and has a pH of around one or less.

•  It is highly corrosive, making it dangerous to touch.

In sulfuric acid, there is 1 sulphur atom, 4 oxygen atoms, and two hydrogen atoms that bond directly to two oxygen atoms to form two OH groups. Molecules are covalently bonded and have a tetrahedral structure. 

Molecular Weight of Sulphuric Acid 

The molecular mass is the mass of a substance, which is calculated by adding up the atomic mass of every atom present in one molecule of that substance. 

 

Sulphuric Acid contains three types of atoms, and we need to know the atomic mass of each of those. They are written below.

 

Atomic Mass of Hydrogen = 1 u

Atomic Mass of Sulphur = 32 u

Atomic Mass of Oxygen = 16 u

(Note: The above masses are a good approximation. We have excluded decimals for easier calculation)

 

We know that one molecule of hydrogen sulphate contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen, the masses of which are given below.

 

Mass of 2 Hydrogen Atoms = 1 x 2 = 2 u

Mass of 1 Sulphur Atom = 32 u

Mass of 4 Oxygen Atoms = 16 x 4 = 64 u

The molecular mass of hydrogen sulphate is equal to the sum of all its atoms. 

Molecular Mass of Hydrogen Sulphate = 2 + 32 + 64

                                                                     = 98 u

Therefore, the molecular mass of Sulphuric Acid is 98 u. 

 

H2SO4 Molar Mass

Molar mass is the mass of one mole of a substance, measured in grams. One mole of a substance is defined as the Avogadro number (6.023 x 1023) molecules of that substance. 

 

Using the atomic mass of an individual atom and multiplying that by the conversion factor grams per mole (g/mol), you can determine the molar mass of that element.

 

The molar mass constant (our conversion factor) is defined as 0.001 kg/mol or 1 g/mole. Therefore, the Sulphuric Acid molar mass is 98 g/mole. 

 

The molecular formula of sulfuric acid, H2SO4 shows that one molecule of sulfuric acid (H2SO4) contains 2 moles of hydrogen atoms, 1 mole of sulfur, and 4 moles of oxygen atoms. Therefore, the molecular mass of H2SO4 is equal to the sum of the masses of 2 mol of the hydrogen atom, 1
mol of the sulfur atom, and 4 mol of the oxygen atom. The atomic weight of hydrogen is 1u, the atomic weight of sulfur is 32u, the atomic weight of oxygen is 16u, and the molecular weight of sulfuric acid can be calculated as follows. 

Molecular weight of H2SO4 = mass of  2 mol hydrogen atom + mass of 1 mol sulfur + mass of 4 mol oxygen atom 

= (2 × 1) + 32 +( 4 × 16 )

= 2 + 32 + 64 

= 98u 

Therefore, the molecular weight of sulfuric acid is 98u and the molecular weight of sulfuric acid is 98 g / mol. 

Sulphuric Acid Uses

1. It is used to make fertilisers. 

2. It is used in the manufacture of steel and iron. It is also used as a cleaning agent in the industrial sector to erase rust from steel and iron.

3. It is used in the chemical manufacturing industry. It is used to make phosphoric acid, hydrochloric acid, nitric acid, sulphate salts, synthetic detergents, dyes and pigments, explosives, medicines, and ammonium sulphate.

4. It is used for oil processing.

5.It functions as a catalyst in the reaction to convert cyclohexanone oxime to caprolactam. This reaction is used in the production of nylon.

6. It is used to make batteries. In lead-acid batteries, Sulphuric Acid functions as an electrolyte. It can be used in storage batteries. Since it is present in a car battery, it is also known as car battery acid. 

7. In the industry: 

Up to 50% of this produced liquid is used in the production of phosphoric acid, which is used in the production of phosphoric acid fertilizers. It is also used in the manufacture of Pigment, paints, plastics etc, manufacture of metals such as copper and zinc, 5% of the acid produced is used in the production of fibres, the manufacture of explosives and drugs, in leather and petroleum industry etc. It is used in most industries. 

8. At Home: 

It is a very dangerous chemical and should be handled with a lot of care. It is used in acid drain cleaners.  Due to its high drainage, it can be used to remove the tissue paper.  

9. Catalyst: 

It is used as a catalyst in the nylon manufacturing process. Used in the Mannheim process in the manufacture of HCl. 

10. Drugs and Ointment 

It is used to damage the  DNA of cancer cells in the manufacture of chemotherapeutic agents. It is also used in ointments to treat various skin infections. 

Physical Properties of Sulphuric Acid 

1. Pure sulfuric acid is a colourless, odourless, high density, oily liquid with a specific gravity of 1.84 at 288 K. 

2. It is highly soluble in water at all concentrations.

3. It contains 97.3% of acid and boils at 611 K. Therefore, aqueous sulfuric acid cannot be concentrated above 97.3% by boiling. 

4. It will fume in the humid air.  

5. If sulphuric acid touches the skin, it can cause severe burns.

Solved Examples

Question 1. Show the Reaction Between Sulphuric Acid and potassium.

Answer:

Acids react with active metals to form metal salts and hydrogen gas. Potassium reacts with Sulphuric Acid to form potassium sulphate and hydrogen gas. 

H2SO4 + 2K————> K2SO4 + H2

Tartaric acid is an organic di-carboxylic compound. Its molecular formula is C4H4O6. It is also known as racemic acid. It contains two stereocentres. Its IUPAC name is 2,3-dihydroxybutanedioic acid. It is acidic in nature. Tartaric acid found in many fruits like grapes, tamarinds, banana, and citrus fruits. Tartaric acid is present in many sour vegetables like a tomato.

Structure And Uses of Tartaric Acid

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The tartaric acid molecule exists in three forms: 

• Neutral bi-acid form

• Monotartrate form

• Bitartrate form

Tartaric acid is a chiral molecule with two carboxylic groups. It naturally occurs in Dextro or Levo form.

(Image to be added soon) Dextro form

(Image to be added soon) Levo form

Properties of Tartaric Acid

• It exists in a white granular to crystalline form.

• It is an odourless compound.

• It has pleasant acidulous taste.

• Its melting point is 173.625 degrees celsius.

• Its flash point is 210 degrees celsius.

• It is soluble in water.

• Its molecular mass is 150.087 g/mol.

• Its density is 1.79 g/mol.

• Tartaric acid is reactive in nature. Example of tartaric acid as a reactive molecule is given below:

HO2CCH(OH)CH(OH)CO2H + H2O2 → HO2CC(OH)C(OH)CO2H + 2H2O 

Tartaric Acid Uses

• It is used in food additives.

• It is used in many drugs.

• It is used as a flavouring agent.

• It is used as a dusting powder on gloves.

• It is used in the manufacturing of candies.

• Its salt is used in removing sulphur dioxide from the waste.

• It is used in making silver mirrors.

• It is generally mixed with baking soda and used in baking. As it evolves carbon dioxide this helps in the baking process.

Did You Know?

• Tartaric acid can be absorbed into the body by inhalation.

• Tartaric acid can cause a burning sensation and shortness in breathing.

• Exposure of tartaric acid on the skin can cause redness and skin irritation.

• It can cause severe redness and pain in the eyes.

TEL stands for tetraethyl lead (also known as tetraethyl lead) and is an organolead compound with the formula (CH3CH2)4Pb, where the lead formula is Pb. It’s a petro-fuel additive that was first mixed with gasoline in the 1920s as a patented octane rating booster that enabled engines to run at higher compression levels. As a result, vehicle efficiency and fuel economy improved. TEL’s antiknock efficacy was discovered in 1921 by the General Motors research laboratory, which had spent many years trying to find an additive that was both highly efficient and inexpensive.

Later, concerns about the toxic effects of lead, especially on children, were raised. Catalytic converters are also poisoned by lead, which is also a major cause of spark plug fouling. Many countries started phasing out and ultimately banning TEL in automotive fuel as early as the 1970s. According to an UN-backed report from 2011, the elimination of TEL resulted in $2.4 trillion in annual benefits and 1.2 million fewer premature deaths.

This article will study tetraethyl lead anti-knocking agent and tetraethyl lead uses in detail.

The Reaction For the Formation of Tetraethyl Lead

Chloroethane is combined with sodium–lead alloy to create TEL.

4 NaPb + 4 CH 3CH2Cl → (CH3CH2)4Pb + 4 NaCl + 3 Pb

Steam distillation is used to recover the product, leaving a sludge of lead and sodium chloride. TEL is a colourless, viscous liquid. TEL is strongly lipophilic and soluble in petrol since it is charge neutral and contains an exterior of alkyl groups (gasoline).

Tetraethyl Lead Uses

Tetraethyl lead is used as:

1. Beginning in the 1920s, TEL was widely used as a gasoline additive, where it acted as an effective antiknock agent and prevented exhaust valve and valve seat wear. Concerns about the potential health effects of fine lead particles in the atmosphere were posed almost immediately in authoritative journals.

2. Tetraethyllead acts as a barrier between the hot exhaust valves and their seats, preventing micro welds from developing. When these valves reopen, the micro welds separate, leaving a rough surface on the valves that abrade the seats, causing valve recession. As lead was phased out of motor fuel, automakers started specifying reinforced valve seats and improved exhaust valve materials to avoid valve recession in the absence of lead.

3. Tetraethyl lead anti knocking agent: To prevent uncontrolled combustion, known as engine knocking, a gasoline-fueled reciprocating engine needs fuel with a high octane level (knock or ping). Tetraethyl lead anti knocking agents allow higher compression ratios to be used, resulting in increased efficiency and peak power. Adding varying quantities of additives to gasoline, such as low percentage TEL or high percentage ethanol, allowing for simple and inexpensive octane control. TEL had the added benefit of being commercially viable because its application for this purpose could be patented. TEL, which was used in WWII, achieved 150 octanes, allowing supercharged engines like the Rolls-Royce Merlin and Griffon to achieve high horsepower ratings at a low cost.

4. Because of concerns about air and soil lead levels, as well as the accumulative neurotoxicity of lead, most developed countries phased out TEL from road vehicle fuels by the early 2000s. The use of catalytic converters, which were required in the United States for 1975 and newer model-year cars to comply with stricter emissions regulations, began the gradual phase-out of leaded gasoline in the United States.

5. Several advancements in automotive engineering and petroleum chemistry have reduced the need for TEL. Other antiknock additives of varying toxicity, such as metallic compounds such as methylcyclopentadienyl manganese tricarbonyl (MMT) and oxygenates such as methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and ethyl tert-butyl ether (ETBE), as well as other antiknock additives of varying toxicity, such as methyl (ETBE).

Lead Tetraacetate

The chemical compound Pb(C2H3O2)4 is also known as lead(IV) acetate or lead tetraacetate. It’s a colourless solid that’s soluble in nonpolar organic solvents, but it’s not salt. Moisture degrades it, so it’s normally stored with more acetic acid. The compound is used in the synthesis of organic compounds.

Did You Know?

Antiknock agents are divided into two categories: high-percentage additives like alcohol and low-percentage additives like heavy metals. Since the key issue with TEL is its lead content, a variety of alternative additives containing less toxic metals have been investigated. For a time, methylcyclopentadienyl manganese tricarbonyl (MMT), a manganese-carrying additive, was used as an antiknock agent, but its protection has been questioned, and it has been the subject of bans and lawsuits. Ferrocene, an organometallic iron compound, is also used as an antiknock agent, though it has a number of disadvantages.