Class 12 Chemistry Chapter 5 Surface Chemistry Notes PDF

Stuck with Surface Chemistry Class 12 Notes that just feel too much? Don’t worry, this chapter is easier than it looks. It’s all about what happens at the surface - between solids, gases, and liquids. Simple, right!

From adsorption and catalysis to colloids, these concepts show up in real life and exams. So if you want no-fluff, straight-to-the-point chemistry class 12 surface chemistry notes, you're in the right place.

Surface Chemistry Class 12 Notes

If you're searching for the kind of chemistry class 12 surface chemistry notes that actually make sense, you're in the right place. No long-winded textbook stuff - just clear concepts, sorted sections, and a format that’s made for last-minute revisions.

Whether it’s surface chemistry short notes, key terms from ch 5 chemistry class 12 notes, or just a fresh way to understand adsorption, catalysis, and colloids - we’ve covered it all right here.

What is Surface Chemistry?

Surface chemistry is the part of chemistry that deals with everything happening at the surface or boundary of two substances - like a solid touching a gas, or a liquid touching air. It doesn’t focus on the entire material, just the outer layer where two phases meet.

You’ll come across terms like solid-gas interface, solid-liquid interface, and more. Real-life examples? Think of rust forming on iron, charcoal absorbing gases, or how catalysts work in industries. It all begins at the surface.

This chapter helps you understand how those surface reactions happen, why they matter, and where we use them in daily life and industries.

Adsorption – Key Concept in Surface Chemistry Class 12

Adsorption is one of the most important topics in surface chemistry class 12 notes. It’s the process where molecules from a gas or liquid gather on the surface of a solid or liquid. Unlike absorption, where particles go into the material, adsorption only happens on the surface.

Types of Adsorption

There are two main types of adsorption you need to remember clearly:

1. Physisorption (Physical Adsorption)

This is the simpler one. In physisorption, particles are held on the surface by weak forces (like van der Waals forces). There’s no actual chemical bonding here. It’s reversible and usually happens at lower temperatures. Also, it can form multiple layers of particles on the surface.

2. Chemisorption (Chemical Adsorption)

This one’s stronger. In chemisorption, the particles form a real chemical bond with the surface. It usually happens at higher temperatures, forms only one layer (monolayer), and is not easily reversible. It’s also very specific - the adsorbate and the surface have to be a good match.

Factors like temperature, pressure, and surface area affect how much adsorption occurs. Powdered substances, for example, adsorb more because they offer more surface area.

You’ll also study two major isotherms in this part of chemistry class 12 surface chemistry:

Adsorption Isotherms

This part of your notes of surface chemistry includes two important graphs to explain how adsorption works:

• Freundlich Isotherm

An experimental equation showing that adsorption increases with pressure:
xm=kP1/n\frac{x}{m} = kP^{1/n}mx​=kP1/n
(x = mass adsorbed, m = mass of adsorbent, P = pressure, k & n = constants)

• Langmuir Isotherm

A theoretical model assuming monolayer adsorption. It shows that after a certain pressure, adsorption becomes constant (saturation point).

From air filters and water purifiers to industrial separations, this section of your surface chemistry short notes plays a major role in both daily life and board exams.

Catalysis – Part of Chemistry Surface Chemistry Notes

Catalysis is a scoring and important part of your surface chemistry class 12 notes. It explains how the rate of a chemical reaction can be increased using a catalyst, without the catalyst getting consumed in the process.

What is Catalysis?

Catalysis is the process in which the speed of a chemical reaction is increased by adding a substance called a catalyst, which remains unchanged at the end of the reaction.

Types of Catalysis

There are two main types of catalysis in this chapter:

1. Homogeneous Catalysis

• Catalyst and reactants are in the same phase (all gas or all liquid)
• Example: In the lead chamber process, SO₂ and O₂ react in the presence of NO gas (all gases)

2. Heterogeneous Catalysis

• Catalyst and reactants are in different phases
• Usually: solid catalyst + gaseous reactants
• Example: In the Haber process, iron (solid) acts as a catalyst for nitrogen and hydrogen gases

Adsorption Theory of Heterogeneous Catalysis

This theory explains how solid catalysts work:

• Reactants first get adsorbed on the surface of the solid catalyst
• A chemical reaction happens on the surface
• Products are formed and then desorbed (leave the surface)
• The catalyst surface is now free for more reactants

This is why finely powdered catalysts work better - more surface area = more reactions.

Some Extra Terms (Class 12 Must-Know)

• Promoters: Substances that increase catalyst efficiency
  Example: Molybdenum (Mo) promotes iron in the Haber process
  
  
• Catalyst Poisons: Substances that reduce or stop catalyst activity
  Example: Arsenic (As) poisons platinum catalysts

Colloids and Emulsions in Surface Chemistry Class 12

This part of your surface chemistry class 12 notes covers colloidal solutions - mixtures where particles are bigger than in true solutions, but too small to settle down.

What is a Colloid?

A colloid is a system in which the size of the dispersed particles is between 1 nm and 1000 nm. These particles are evenly spread in another substance (called the dispersion medium), and they do not settle on standing.

Components of a Colloidal System

• Dispersed phase – The particles being distributed
• Dispersion medium – The substance in which they are dispersed

Example: In milk, fat is the dispersed phase and water is the dispersion medium.

Types of Colloids (Based on Physical State)

Here’s a quick table to revise the types:

‍

Emulsions (Liquid-Liquid Colloids)

Emulsions are a special type of colloid where both the dispersed phase and the medium are liquids.

Two main types:

• Oil-in-water: Oil is dispersed in water (like milk)
• Water-in-oil: Water is dispersed in oil (like butter)

Since they’re not very stable, emulsifying agents like soaps or detergents are used to keep them mixed properly.

Properties of Colloids (Important for Boards)

• Tyndall effect – Light scatters when passed through a colloid
• Brownian motion – Random zig-zag movement of particles
• Charge on particles – Colloidal particles carry either +ve or -ve charge
• Coagulation – The process of settling down of particles (by adding electrolytes)

Applications of Colloids

• Fog removal in industries
• Blood clotting
• Formation of delta
• Medicines and antiseptics
• Cleaning with soaps and detergents

Important Diagrams for Surface Chemistry Class 12

These are the diagrams commonly asked in CBSE exams or needed to understand concepts better. Add them to your surface chemistry short notes for quick revision.

1. Adsorption Isotherms

• Freundlich Isotherm: A curve showing that adsorption increases with pressure, but not linearly.

Formula: xm = kP1/n\frac{x}{m} = kP^{1/n}mx = kP1/n
x = amount adsorbed, m = mass of adsorbent, P = pressure

• Langmuir Isotherm: A graph that shows adsorption rises with pressure but reaches a constant value (monolayer formation).

2. Classification of Colloids (Based on Physical State)

A table/chart format showing combinations of dispersed phase and dispersion medium.
Example:

• Solid in liquid = Sol (e.g., paint)
• Liquid in liquid = Emulsion (e.g., milk)

3. Charge on Colloids (Optional Diagram)

A simple labeled diagram of a positively or negatively charged colloid surrounded by counter ions - often used to explain electrophoresis or coagulation.

These diagrams are small but important scoring tools in your surface chemistry class 12 notes - don’t skip practicing them with labels.

Applications of Surface Chemistry Class 12 Chapter

This part of your surface chemistry class 12 notes covers the real-life and industrial use of key concepts like adsorption, catalysis, and colloids. These are not just theory - they’re common board exam topics too.

1. Applications of Adsorption

• Gas masks: Activated charcoal adsorbs harmful gases in polluted environments.
• Water purification: Charcoal is used to remove organic impurities from drinking water.
• Adsorption indicators: Used in volumetric analysis to show the end point of a reaction.
• Drug action: Medicines are adsorbed on body tissues to target the required area more effectively.

2. Applications of Catalysis

• Haber process: Iron (Fe) catalyst is used for manufacturing ammonia.
• Contact process: V2O5​​ catalyst is used in the production of sulphuric acid.
• Hydrogenation of oils: Nickel (Ni) acts as a catalyst to convert vegetable oil into solid fat (vanaspati).
• Catalytic converters: Used in vehicles to convert harmful exhaust gases into safer compounds.

3. Applications of Colloids

• Medicines: Many drugs are colloidal in nature, which helps in easy absorption.
• Cleansing agents: Soaps form colloidal micelles to remove dirt and grease.
• Food products: Items like milk, butter, and ice cream are colloidal systems.
• Industrial uses: Colloids are used in the preparation of inks, paints, and photographic plates.

These applications are a frequently asked topic in exams - revise the names, examples, and the process involved to score full marks from this section of your chemistry surface chemistry notes.

Conclusion 

And that’s a wrap on Surface Chemistry - one of the shortest but sneakiest chapters in Class 12 Chemistry. Not too scary now, right! From all that “adsorption vs absorption” drama to real uses of catalysts and colloids - you’ve made it through the chaos, and now it actually makes sense. 

If this blog helped even a little, that’s a win. One more chapter down, and you're officially ahead of the panic crowd.

FAQs

Q1. What is surface chemistry in simple words?
Ans. It’s the study of chemical reactions that happen only at the surface of solids or liquids - like how gases stick or react at those surfaces.

Q2. What is an adsorption isotherm?
Ans. It’s a graph that shows how much gas sticks to a solid surface at a constant temperature as pressure changes. The two key types are:

• Freundlich isotherm (empirical curve)
• Langmuir isotherm (monolayer theoretical model) 

Q3. What is the Tyndall effect?
Ans. It’s the scattering of light by particles in a colloid, which makes the light beam visible when shined through it.

Q4. Why is chemisorption called activated adsorption?
Ans. Because it involves forming chemical bonds at the surface and requires extra energy (activation energy) to happen.

Q5. What are the types of emulsions?
Ans. Two types:

• Oil-in-water (O/W) – oil droplets in water (e.g., milk)
• Water-in-oil (W/O) – water droplets in oil (e.g., butter)