Grade 12
  1. Solid state  1.1. Classification of solids  1.2. Crystal Lattice and Unit Cell  1.3. Packing Efficiency  1.4. Density of unit cell  1.5. Imperfections in solids (point and line defects)  1.6. Electrical Properties of Solids (Conductors, Insulators and Semiconductors)  1.7. Magnetic Properties of Solids (Diamagnetic, Paramagnetic and Ferromagnetic Materials)
  2. Solution  2.1. Types of Solutions (Homogeneous and Heterogeneous)  2.2. Expressing concentration of solutions (mass %, volume %, molarity, molality, normality, mole fraction)  2.3. Solubility of solids and gases in liquids (Henry's law)  2.4. Raoult's Law and Ideal and Non-Ideal Solutions  2.5. Syndrome properties  2.6. Abnormal molar mass and Van't Hoff factor
  3. Electrochemistry  3.1. Electrochemical cells (galvanic and electrolytic cells)  3.2. Galvanic cell and EMF of the cell  3.3. Standard electrode potential and electrochemical series  3.4. Nernst equation and its applications  3.5. Conductivity and electrolytic cells (specific, molar and equivalent conductivity)  3.6. Kohlrausch's law and its applications  3.7. Batteries (primary and secondary cells)  3.8. Corrosion and its prevention
  4. Chemical kinetics  4.1. Rate of chemical reaction  4.2. Factors affecting the reaction rate (concentration, temperature, catalyst, surface area)  4.3. Order and molecularity of the reaction  4.4. Integrated Rate Equations (Zero, First and Second Order)  4.5. Half-life of a reaction  4.6. Collision theory and activation energy  4.7. Arrhenius equation and its applications
  5. Surface chemistry  5.1. Adsorption and its types (Physicosorption and Chemisorption)  5.2. Catalysis and its types (homogeneous and heterogeneous)  5.3. Colloids and their properties (Tyndall effect, Brownian motion, coagulation)  5.4. Emulsions and gels  5.5. Applications of Colloids
  6. General principles and processes of separation of elements  6.1. Presence of metals and minerals  6.2. Concentration of ores (gravity separation, froth flotation, magnetic separation)  6.3. Extraction of raw metals (roasting, calcination, reduction)  6.4. Thermodynamic and electrochemical principles of metallurgy  6.5. Refining of metals
  7. P-block elements  7.1. Group 15 elements (nitrogen and phosphorus)  7.2. Group 16 Elements (Oxygen, Sulphur and their Compounds)  7.3. Group 17 Elements (Halogens and their Compounds)  7.4. Group 18 Elements  7.5. Properties and Trends in p-Block Elements  7.6. Important compounds of p-block elements (ammonia, phosphine, sulphuric acid, hydrochloric acid)  7.7. Interhalogen compounds and their applications
  8. d-block and f-block elements  8.1. General Properties of Transition Metals  8.2. Properties of Inner Transition Metals (Lanthanoids and Actinoids)  8.3. Lanthanoid and actinoid contractions  8.4. Coordination Chemistry of d-Block Elements
  9. Coordination compounds  9.1. Werner's theory and modern concepts  9.2. Coordination number and type of ligand  9.3. Nomenclature of Coordination Compounds  9.4. Isomerism (geometrical and optical) in coordination compounds  9.5. Bonding in Coordination Compounds (Valence Bond Theory and Crystal Field Theory)  9.6. Stability and applications of coordination compounds in medicine and industry
  10. Haloalkanes and haloarenes  10.1. Classification and nomenclature of haloalkanes and haloarenes  10.2. Physical and Chemical Properties of Haloalkanes and Haloarenes  10.3. Mechanism of Nucleophilic Substitution Reactions (SN1 and SN2)  10.4. Uses and environmental effects (ozone depletion, CFCs)
  11. Alcohol, phenol and ether  11.1. Structure and classification of alcohols, phenols and ethers  11.2. Preparation and properties of alcohols  11.3. Preparation and properties of phenol  11.4. Preparation and properties of ethers  11.5. Chemical Reactions and Uses
  12. Aldehydes, ketones and carboxylic acids  12.1. Structure and nomenclature in aldehydes, ketones and carboxylic acids  12.2. Preparation and properties of aldehydes and ketones  12.3. Chemical reactions in aldehydes, ketones and carboxylic acids (nucleophilic addition, oxidation and reduction)  12.4. Preparation and Properties of Carboxylic Acids  12.5. Chemical Reactions and Uses of Carboxylic Acids
  13. Nitrogen-containing organic compounds  13.1. Amines (classification, structure, basicity)  13.2. Preparation and properties of amines  13.3. Reactions of Amines (Diazotization, Carbylamine Reaction)  13.4. Diazonium salts and their applications in paint industry
  14.1. Carbohydrates (classification and properties)  14.2. Proteins (Structure and Function)  14.3. Enzymes (Mechanism and Function)  14.4. Nucleic acids (DNA and RNA)  14.5. Vitamins and hormones
  15. Polymer  15.1. Classification of Polymers (Addition, Condensation, Copolymers)  15.2. Types of polymerization (free radical, ionic, condensation)  15.3. Important Polymers and Their Uses  15.4. Biodegradable and non-biodegradable polymers
  16. Chemistry in Everyday Life  16.1. Drugs and their classification (analgesics, antipyretics, antibiotics, antacids)  16.2. Chemicals in food and cosmetics (preservatives, artificial sweeteners, antioxidants)  16.3. Cleaning agents and detergents (soaps, synthetic detergents, surfactants)  16.4. Environmental Chemistry (Pollution, Green Chemistry, Sustainable Chemistry)

Grade 12 ↓


Surface chemistry


Surface chemistry is the study of the chemical phenomena that occur at the interface of two phases, usually between a gas and a solid, a gas and a liquid, a liquid and a solid, or two immiscible fluids such as oil and water. This area of chemistry enables us to understand the processes that occur at the boundaries between different phases and includes the study of adsorption, catalysis, colloids, and surface tension.

The concept of absorption

Adsorption is a key principle in surface chemistry. It refers to the accumulation of particles or molecules on the surface of a substance. This can occur with gases or liquids accumulating on solid surfaces. The substance on whose surface adsorption occurs is called the adsorbent, and the substances that adsorb are called adsorbents.

Types of absorption

There are two main types of adsorption: physical adsorption (physisorption) and chemical adsorption (chemisorption).

Physical absorption (physisorption)

In physisorption, the adsorbate molecules are held on the surface of the adsorbent by weak van der Waals forces. This is a non-specific type of adsorption and can occur with most gases on any solid surface. It is usually reversible. An example of physisorption is O 2 adsorbed on charcoal.

Chemical absorption (chemisorption)

Chemisorption involves the formation of a chemical bond between the adsorbent and the surface of the adsorbent. It is highly specific and is often irreversible due to the high energy involved in forming the chemical bond. An example of chemisorption is the adsorption of hydrogen on nickel during hydrogenation reactions.

Factors affecting absorption

Several factors can affect the amount and rate of absorption, including:

  1. Nature of adsorbent: Porous and finely divided materials generally make better adsorbents because of their large surface area.
  2. Nature of adsorption: The adsorption capacity of a molecule depends upon its chemical structure, size and polarity.
  3. Pressure: Generally, increase in pressure increases the extent of adsorption because it forces more gas molecules onto the surface.
  4. Temperature: Physical adsorption is usually exothermic and decreases as temperature increases, while chemisorption, being endothermic, can increase with temperature.

Absorption isotherm

Adsorption isotherm equations describe how the concentration of the adsorbate on an adsorbent changes with pressure (for gases) or concentration (for solutions) at constant temperature.

Freundlich adsorption isotherm

The Freundlich adsorption isotherm is an empirical relationship that indicates the increase in adsorption with pressure. The formula is:

x/m = kP 1/n

Here x is the mass of the adsorbate, m is the mass of the adsorbent, P is the pressure, and k and n are constants.

Langmuir adsorption isotherm

The Langmuir isotherm is based on the assumption that adsorption sites are equally available, and each site can hold only one molecule. The formula is:

θ = (bP) / (1 + bP)

where θ is the fraction of surface covered, b is a constant related to the affinity between the adsorbent and the adsorbed substance, and P is the pressure.

Role of surface chemistry in catalysis

Catalysis involves the acceleration of chemical reactions by substances called catalysts, which are not themselves consumed in the reaction. Surface chemistry is important in heterogeneous catalysis, where reactions take place on the surface of solid catalysts.

Mechanism of catalysis

This mechanism typically involves the adsorption of reactants on the catalyst surface, where they interact to form products, which are then removed, leaving the catalyst ready to facilitate more reactions. This mechanism highlights the importance of the surface properties of the catalyst.

Example of a catalytic reaction

A classic example of a surface catalytic reaction is the hydrogenation of ethylene using a platinum catalyst. The reaction proceeds as follows:

C 2 H 4 (g) + H 2 (g) ⇌ C 2 H 6 (g)

Applications of surface chemistry

Surface chemistry has many applications in various fields:

  • Environmental science: Adsorption is used to remove pollutants from air and water in pollution control.
  • Medicine: Absorption processes are used in the development of drug delivery systems and diagnostic devices.
  • Industrial processes: Catalytic converters, which rely on surface chemistry, are used to reduce harmful emissions from vehicles.

Understanding surface energy and wettability

Surface energy is the extra energy present at the surface of a substance, compared with its bulk, which can affect how liquids spread across a surface. Wetting is determined by the balance of surface energy between the liquid, the solid, and the surrounding air.

Contact angle

The contact angle is the angle between the tangent at the liquid-solid interface and the solid surface. It is a measure of wetting, with smaller angles indicating better wetting.

θ Solid

Conclusion

Surface chemistry is an essential branch of chemistry that helps us understand the interactions that occur at the interfaces of materials. It has useful applications in technology, industry, and environmental science, helping us solve complex problems related to reactions, material absorption, and the design of advanced materials. Through studying surface chemistry, we gain more insight into the chemical processes that pervade our everyday world.


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Surface chemistry

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