All questions of Adsorption for Chemistry Exam

Here during adsorption. Gas is absorbed on the surface of metal... So entropy is decrease here. And during adsorption the heat is liberated. Which is call heat of adsorption. So due to heat is liberated the process is exothermic and dH will be negative too. And dST will be also negative because dS is negative and T never be negative so dST will be negative too.

°C. Calculate the amount of acetic acid adsorbed by 1 kg of charcoal at the same conditions.

To calculate the amount of acetic acid adsorbed by 1 kg of charcoal, we need to convert the given values to the same units.

1 kg of charcoal is equal to 1000 g.

The surface area of 1 g of charcoal is given as 100 m2 per gram.

Therefore, the surface area of 1000 g (1 kg) of charcoal is 1000 * 100 = 100,000 m2.

The amount of acetic acid adsorbed by 1 g of charcoal is given as 60 mg.

To find the amount of acetic acid adsorbed by 1 kg of charcoal, we multiply the amount adsorbed by 1 g by the mass of charcoal:

60 mg/g * 1000 g = 60,000 mg

To convert mg to grams, we divide by 1000:

60,000 mg / 1000 = 60 g

Therefore, 1 kg of charcoal at the same conditions will adsorb 60 g of acetic acid.

Langmuir isotherm is a model that explains the adsorption phenomenon on a solid surface. It is named after Irving Langmuir, who proposed this model in 1916. The true statements about Langmuir isotherm are:

Valid for Monolayer Coverage:
Langmuir isotherm is valid for monolayer coverage, which means that it assumes that only one layer of gas molecules is adsorbed on the surface of the solid. This assumption is valid when the surface of the solid is homogeneous and the adsorption sites are equivalent.

All Adsorption Sites are Equivalent:
Langmuir isotherm assumes that all the adsorption sites on the surface of the solid are equivalent. It means that the probability of adsorption of gas molecules on any adsorption site is the same.

There is Dynamic Equilibrium between Free Gas and Adsorbed Gas:
Langmuir isotherm assumes that there is a dynamic equilibrium between the free gas molecules and the adsorbed gas molecules on the surface of the solid. At equilibrium, the rate of adsorption is equal to the rate of desorption.

Adsorption Probability is Independent of Occupancy at the Neighboring Sites:
Langmuir isotherm assumes that the probability of adsorption of gas molecules on a particular site is independent of the occupancy of the neighboring sites. It means that the adsorption probability is not affected by the presence or absence of adsorbed gas molecules on the neighboring sites.

In conclusion, Langmuir isotherm is a useful model to understand the adsorption phenomenon on a solid surface. It assumes that the adsorption sites are equivalent, there is a dynamic equilibrium between the free gas and the adsorbed gas, the probability of adsorption is independent of the neighboring sites, and it is valid for monolayer coverage.

The adsorption of gases on charcoal is influenced by several factors, including the nature of the gas molecules and the properties of the charcoal surface. In this case, we are given four gases: CO2, SO2, CH4, and H2, and we need to determine which gas shows the least adsorption on a definite amount of charcoal.

To predict the gas with the least adsorption, we can consider the following factors:

1. Molecular Size: The size of the gas molecules can affect their adsorption on the charcoal surface. Smaller molecules can penetrate the pores of the charcoal more easily, leading to stronger adsorption. Larger molecules may have difficulty accessing the charcoal surface and thus show weaker adsorption.

2. Polarity: The polarity of the gas molecules can also affect their adsorption. Polar molecules have dipole moments, which can interact with polar sites on the charcoal surface through dipole-dipole interactions. Nonpolar molecules, on the other hand, do not have dipole moments and may have weaker interactions with the charcoal surface.

Based on these factors, we can analyze the given gases:

a) CO2: Carbon dioxide is a relatively small molecule (linear with a molecular weight of 44 g/mol). It is also a polar molecule due to its linear geometry and the presence of polar carbon-oxygen bonds. CO2 can undergo dipole-dipole interactions with the charcoal surface, leading to moderate adsorption.

b) SO2: Sulfur dioxide is a larger molecule compared to CO2 (bent shape with a molecular weight of 64 g/mol). It is also a polar molecule due to the presence of polar sulfur-oxygen bonds. SO2 can undergo dipole-dipole interactions with the charcoal surface, similar to CO2. However, the larger size of SO2 may limit its access to the charcoal surface, resulting in weaker adsorption compared to CO2.

c) CH4: Methane is the smallest molecule among the given gases (tetrahedral shape with a molecular weight of 16 g/mol). It is a nonpolar molecule as it consists of only carbon-hydrogen bonds. Methane does not have a dipole moment and lacks the ability to form strong dipole-dipole interactions with the charcoal surface. Therefore, methane is expected to show weaker adsorption compared to CO2 and SO2.

d) H2: Hydrogen gas is the smallest molecule among the given gases (diatomic with a molecular weight of 2 g/mol). It is also a nonpolar molecule as it consists of two hydrogen atoms bonded together. Similar to methane, hydrogen gas lacks a dipole moment and strong dipole-dipole interactions with the charcoal surface. Therefore, hydrogen gas is expected to show weaker adsorption compared to CO2 and SO2.

Based on the analysis above, we can conclude that SO2 shows the least adsorption on a definite amount of charcoal among the given gases (CO2, SO2, CH4, and H2).

According to langmuir Adsorption isotherm the amount of gas adsorbed at very high pressures reaches a constant limiting volume.

The molecular formula of stearate ion is C17H35COO-.

B)CO2
c)NaCl
d)C6H12O6

The correct answer is c) NaCl (sodium chloride)

The order of adsorption of gases NH3, CO2 and H2 by 1 g charcoal at 300 K and 1 atm pressure is given by option 'B', i.e., NH3, CO2, H2.

Explanation:
Adsorption is the process of accumulation of molecules of a substance on the surface of another substance. In this case, the gases NH3, CO2, and H2 are adsorbed by 1 g charcoal at 300 K and 1 atm pressure. The order of adsorption is determined by the force of attraction between the gas molecules and the charcoal surface.

NH3 has the highest order of adsorption because it has the highest dipole moment among the three gases. The dipole moment of NH3 allows it to form hydrogen bonds with the polar surface of charcoal, which results in a stronger force of attraction between NH3 and charcoal.

CO2 has the second-highest order of adsorption because it is a polar molecule and can form weak van der Waals forces with the surface of charcoal.

H2 has the lowest order of adsorption because it is non-polar and cannot form any significant interaction with the surface of charcoal.

Therefore, the order of adsorption of gases NH3, CO2, and H2 by 1 g charcoal at 300 K and 1 atm pressure is NH3 > CO2 > H2, which is given by option 'B'.

B hoga

Admin is contradicting his/her own answer. In option a (II) is Chemisorption , now in option C (II) is Physisorption .How is this possible ?? a,d option should be correct.

Micelle Formation

Micelle formation is a process in which molecules with both hydrophilic (water-loving) and hydrophobic (water-hating) parts arrange themselves in a specific manner to form a spherical structure. The hydrophilic part of the molecule is directed towards the aqueous environment, whereas the hydrophobic part is directed towards the center of the micelle.

Incorrect Statement

The incorrect statement from the given options is "In the micelle formation, the water-soluble heads are directed towards the center."

Explanation

The correct statement is "In the micelle formation, the water-soluble heads are on the surface in contact with the water." In micelle formation, the hydrophilic part of the molecule, which is the water-soluble head, is directed towards the surface of the micelle, which is in contact with the aqueous environment. This arrangement of the molecules allows the hydrophobic part, which is the water-insoluble tail, to be shielded from the aqueous environment and directed towards the center of the micelle.

Conclusion

In conclusion, the formation of micelles is an important process that allows molecules with both hydrophilic and hydrophobic parts to arrange themselves in a specific manner. The water-soluble heads of the molecule are directed towards the surface of the micelle, whereas the water-insoluble tails are directed towards the center of the micelle.

**Collodion:**
Collodion is a liquid preparation that is mainly used in medicine and photography. It is a solution of nitrocellulose in a mixture of alcohol and ether. When applied to the skin, collodion forms a flexible film that can be used for wound dressings or as a protective covering.

**Composition:**
Collodion is composed of a 4% solution of a specific substance in an alcohol-ether mixture. The correct answer is option D, nitrocellulose. Nitrocellulose is a highly flammable compound that is produced by nitrating cellulose with a mixture of nitric acid and sulfuric acid. It is commonly used in the production of explosives, lacquers, and films.

**Explanation:**
Nitrocellulose is the correct answer because it is the main ingredient in collodion. When nitrocellulose is dissolved in an alcohol-ether mixture, it forms a solution that can be easily applied to the skin. The alcohol and ether in the mixture help to dissolve the nitrocellulose and create a liquid solution.

When the collodion is applied to the skin, the alcohol and ether quickly evaporate, leaving behind a thin film of nitrocellulose. This film provides a protective barrier and helps to seal wounds. It can also be used as a base for applying medications or other substances to the skin.

**Other Options:**
The other options, nitroglycerin, cellulose acetate, and glycol dinitrate, are not correct answers because they are not commonly used in the preparation of collodion.

- Nitroglycerin: Nitroglycerin is a highly explosive compound that is used in the production of dynamite and as a medication for heart conditions. It is not commonly used in the preparation of collodion.

- Cellulose acetate: Cellulose acetate is a derivative of cellulose that is used in the production of films, fibers, and coatings. While it is similar to nitrocellulose, it is not commonly used in the preparation of collodion.

- Glycol dinitrate: Glycol dinitrate is an explosive compound that is used as a stabilizer in the production of dynamite. It is not commonly used in the preparation of collodion.

Therefore, the correct answer is option D, nitrocellulose.

The gas molecules are attracted to the solid surface.
b) The gas molecules are repelled by the solid surface.
c) The gas molecules do not interact with the solid surface.
d) The gas molecules pass through the solid surface.

A) Inversion temperature

Explanation:

Na3PO4 as the Best Coagulant:
- Na3PO4, also known as sodium phosphate, is the best coagulant for the precipitation of Fe(OH)3sol.
- When Na3PO4 is added to the Fe(OH)3sol solution, it reacts with iron ions to form insoluble FePO4, which precipitates out of the solution.
- The formation of FePO4 helps in the coagulation of the Fe(OH)3sol particles, leading to their precipitation.
- Na3PO4 is an effective coagulant due to its ability to form insoluble compounds with iron ions, facilitating the removal of Fe(OH)3sol from the solution.

Comparison with Other Options:
- Na2HPO3, NaNO3, and Na2SO4 are not as effective as Na3PO4 in precipitating Fe(OH)3sol.
- Na2HPO3 (sodium hypophosphite), NaNO3 (sodium nitrate), and Na2SO4 (sodium sulfate) do not form insoluble compounds with iron ions, making them less suitable for coagulation purposes in this context.

Conclusion:
- In conclusion, Na3PO4 is the best coagulant for the precipitation of Fe(OH)3sol due to its ability to form insoluble FePO4, which helps in the efficient removal of Fe(OH)3sol particles from the solution.

Hydrophilic nature of Stearate ion:

Stearate ion is a negatively charged ion and is derived from stearic acid. It has a long hydrocarbon chain with a carboxylate group (-COO-) at the end. The hydrocarbon chain is nonpolar and hydrophobic in nature, whereas the carboxylate group is polar and hydrophilic in nature.

The hydrophilic nature of the stearate ion is due to the carboxylate group, which is made up of a carbonyl group (-C=O) and a hydroxyl group (-OH), both of which are polar in nature. The carbonyl group is electron-withdrawing, which causes the oxygen atom to become slightly negative, and the carbon atom to become slightly positive. Similarly, the hydroxyl group is electron-donating, which causes the oxygen atom to become slightly negative, and the hydrogen atom to become slightly positive.

The polar nature of the carboxylate group makes it attracted to water molecules, and thus, hydrophilic in nature. This allows the stearate ion to dissolve in water and form a stable solution.

Conclusion:

In conclusion, the head of the stearate ion, which is the carboxylate group, is hydrophilic in nature due to its polar nature.

Protective Power of Lyophilic Colloidal Sol

The protective power of lyophilic colloidal sol refers to its ability to protect colloidal particles from coagulation or aggregation. When a colloidal sol is formed, the particles are dispersed and stabilized in a medium. However, these particles have a tendency to aggregate due to attractive forces between them. The protective power of a lyophilic colloidal sol helps to prevent or minimize this aggregation, thus maintaining the stability of the sol.

Gold Number

The protective power of lyophilic colloidal sol is quantitatively expressed in terms of the Gold Number. The Gold Number is a measure of the amount of an electrolyte required to cause coagulation or aggregation of a given volume of a lyophilic colloidal sol. It is named after Thomas Thomson Gold, who first introduced this concept.

Principle of Gold Number

The principle behind the Gold Number is based on the fact that the addition of an electrolyte to a colloidal sol neutralizes the charge on the colloidal particles. When the charge is neutralized, the repulsive forces between the particles decrease, leading to their aggregation. The Gold Number represents the minimum amount of electrolyte required to cause coagulation under specific conditions.

Determination of Gold Number

To determine the Gold Number, a series of solutions with different concentrations of an electrolyte are prepared. A fixed volume of the colloidal sol is added to each solution, and the mixture is observed for coagulation. The Gold Number is the minimum concentration of the electrolyte that causes coagulation.

Significance of Gold Number

The Gold Number provides a quantitative measure of the protective power of a lyophilic colloidal sol. Higher Gold Numbers indicate greater protective power, as a larger amount of electrolyte is required to cause coagulation. Therefore, a higher Gold Number implies greater stability of the colloidal sol.

Conclusion

In conclusion, the protective power of lyophilic colloidal sol is expressed in terms of the Gold Number. The Gold Number represents the minimum concentration of an electrolyte required to cause coagulation of a given volume of the colloidal sol. It serves as a quantitative measure of the stability of the colloidal sol, with higher Gold Numbers indicating greater protective power.

Nature of gas:
The adsorption of gas on a solid surface depends on the nature of the gas molecules. Different gases have different properties such as size, polarity, and reactivity, which affect their interaction with the solid surface. For example, polar gases are more likely to adsorb on polar surfaces due to the formation of intermolecular forces.

Surface area of adsorbent:
The surface area of the adsorbent plays a crucial role in gas adsorption. A larger surface area provides more sites for gas molecules to interact with, leading to increased adsorption. This is why materials with porous structures or high surface areas, such as activated carbon, are commonly used as adsorbents.

Temperature and pressure:
Temperature and pressure also have a significant impact on gas adsorption. Higher temperatures usually decrease adsorption as the kinetic energy of gas molecules increases, leading to desorption. On the other hand, higher pressures can enhance adsorption by increasing the concentration of gas molecules at the solid surface.

Conclusion:
In conclusion, the adsorption of gas on a solid surface is influenced by the nature of the gas, the surface area of the adsorbent, and the temperature and pressure conditions. Understanding these factors is essential for designing effective adsorption processes in various applications such as gas separation, purification, and catalysis.

B

Understanding Physical Adsorption Isotherms
Physical adsorption, also known as physisorption, involves the weak van der Waals forces between adsorbate molecules and adsorbent surfaces. The isotherm models describe how these molecules interact with the surface at varying pressures and temperatures.
Isotherm Types:
- Langmuir Isotherm: This model assumes monolayer adsorption on a surface with a finite number of identical sites. It is more applicable to chemisorption than physisorption.
- BET Isotherm: The Brunauer-Emmett-Teller (BET) model extends the Langmuir theory to multilayer adsorption. It is primarily used for physical adsorption but is more complex than necessary for simple cases.
- Freundlich Isotherm: This is an empirical model that describes adsorption on heterogeneous surfaces. It is applicable to physical adsorption as it accounts for diverse adsorption sites and interactions among adsorbate molecules.
- Kisluik Isotherm: This is less commonly used and is not specifically tailored for either physisorption or chemisorption.
Why Freundlich is Correct:
- Heterogeneous Surfaces: The Freundlich isotherm accommodates the varied energy of adsorption sites, typical in physical adsorption scenarios.
- Empirical Nature: Its empirical approach allows it to fit experimental data without strict assumptions about the adsorbent surface.
- Multilayer Formation: It can represent multilayer adsorption, a common phenomenon in physical adsorption processes.
Conclusion:
Given these characteristics, the Freundlich isotherm is indeed the most suitable model for describing physical adsorption processes among the options provided.

THE ANSWER GIVEN IN THE ANSWER KEY IS NOT 17 BUT .17 KINDLY RECHECK FIRST . Acc to Freundlich adsorption isotherm, x/m = k.c^1/n x/500 = 0.16 (0.65)^1/2.35 On solving, *x = 66.6g* Initially, we had 3L of 0.65 M ethanol solution i.e. 0.65 × 3 mol = 1.95 mol = 1.95 ×46 g = 89.7 g of ethanol Therefore, after adsorption, mass of ethanol in solution = 89.7 g - 66.6 g = 23.1 g = 23.1/46 mol = 0.502 mol of ethanol Molarity of left ethanol solution. = 0.502 mol/ 3L = 0.167 mol/L Hope it helps :)

Understanding Adsorbents
Adsorbents are materials that can attract and hold particles on their surface. Common examples include carbon, polymers, resins, and clay. Each of these materials has unique properties that enable them to adsorb various substances.
Why "Dry Sponge" is Not an Adsorbent
- A dry sponge primarily functions through absorption, not adsorption.
- Absorption involves soaking up liquids into the material, whereas adsorption is the accumulation of molecules on the surface.
- A dry sponge lacks the specific surface interactions needed for effective adsorption.
Characteristics of Actual Adsorbents
- Carbon: Highly porous, providing a large surface area for adsorption of gases and organic compounds.
- Polymers and Resins: Engineered materials that can selectively adsorb specific ions or molecules based on chemical properties.
- Clay: Naturally occurring minerals with layered structures that can adsorb both organic and inorganic substances due to their high surface area and charge properties.
Conclusion
In summary, while carbon, polymers, resins, and clay are effective adsorbents, a dry sponge operates on the principle of absorption. This distinction clarifies why option 'D' is not classified as an adsorbent. Understanding these differences is crucial in applications involving separation and purification in chemistry.