Table of Contents
Adsorption’s Function in Surface Chemistry
Surface Chemistry – Adsorption: Adsorption is the process of molecules or atoms attaching themselves to the surface of a solid. In surface chemistry, adsorption is often used to refer to the attachment of molecules to the surface of a solid electrode. Adsorption can occur when a solid is placed in contact with a liquid or gas. In some cases, the adsorbed molecules can be removed from the surface by washing with a solvent.
What is Adsorption?
Adsorption is the process of attaching a molecule to a surface. The molecule can be a gas, liquid, or solid.
Mechanism of Adsorption
- Adsorption is the process by which molecules of one substance are attracted to the surface of a solid or liquid. The attraction between the adsorbate and the surface is called adhesion. The adsorbent is the substance that provides the surface.
- There are several mechanisms by which adsorption can occur. The most common are physical adsorption, chemical adsorption, and ion exchange.
- Physical adsorption occurs when the adsorbate molecules are attracted to the surface of the adsorbent by van der Waals forces. These forces are weak intermolecular forces that arise from the overlap of electron orbitals on adjacent molecules.
- Chemical adsorption occurs when the adsorbate molecules are attracted to the surface of the adsorbent by chemical bonds. The most common type of chemical adsorption is called covalent bonding. In covalent bonding, the adsorbate molecules share electrons in such a way that they form a chemical bond with the adsorbent.
- Ion exchange occurs when the adsorbate molecules are attracted to the surface of the adsorbent by ionic bonds. In ionic bonding, the adsorbate molecules exchange electrons with the adsorbent so that each molecule has a net positive or negative charge.
Difference between Absorption and Adsorption
Absorption is the process of taking in something, such as a liquid, gas, or solid, into a body or container.
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.
Types of Adsorption
There are three main types of adsorption: physisorption, chemisorption, and electrostatic adsorption.
- Physisorption is the most common type of adsorption, and occurs when atoms or molecules attach to a surface by physical interactions, such as van der Waals forces.
- Chemisorption is the second most common type of adsorption, and occurs when atoms or molecules attach to a surface by chemical interactions.
- Electrostatic adsorption is the third most common type of adsorption, and occurs when atoms or molecules attach to a surface due to electrostatic forces.
Uses of Adsorption
There are many uses of adsorption. Some of them are:
- Adsorption used to remove impurities from gases and liquids.
- It used to separate mixtures of substances.
- Adsorption used to remove moisture from air.
- It used to remove pollutants from water.
Adsorption Isotherm
The adsorption isotherm is a graphical representation of the relationship between the amount of a gas or vapor adsorbed by a solid and the pressure of the gas or vapor.
Catalysis
The Catalysis Club at Georgia Tech is a student-run organization that promotes and advances the field of catalysis through monthly meetings, workshops, and also outreach activities.
What is Catalysis?
Catalysis is a process that speeds up a chemical reaction without being used up in the reaction.
Types of Catalysis
There are many types of catalysis, but some of the most common are:
- Enzyme catalysis: This occurs when enzymes catalyze the conversion of one molecule into another.
- Acid-base catalysis: This involves the transfer of protons between molecules to speed up a reaction.
- Metal-catalyzed reactions: In these reactions, a metal catalyst helps to speed up the reaction by providing a place for the reactants to bind.
- Photocatalysis: In this type of catalysis, light is used to speed up a reaction.
What is Homogeneous Catalysis and Catalyst?
- A catalyst is a substance that speeds up a chemical reaction without being consumed by the reaction.
- A homogeneous catalyst is one that is dissolved in the same phase as the reactants.
What is Heterogeneous Catalysis and Catalysts?
Heterogeneous catalysis is the process of using a catalyst to speed up a chemical reaction. Catalysts are substances that are not consumed in the reaction and can be used over and over again.
What is Adsorption Theory of Heterogeneous Catalysis?
Adsorption theory of heterogeneous catalysis is a theory that explains how a catalyst works. The theory states that a catalyst works by adsorbing molecules of the reactants to its surface. This causes a change in the energy of the system, which makes it easier for the reactants to react and form the product.
What is Shape Selective Catalysis by Zeolites?
Shape selective catalysis is the ability of a zeolite to catalyze a specific reaction based on the shape of the zeolite’s pores. This ability is due to the fact that zeolites have a high surface area and a large number of small pores that can selectively adsorb certain molecules.
What is Enzyme Catalysis?
Enzyme catalysis is the speeding up of a chemical reaction by the presence of a special molecule called an enzyme. Therefore enzymes are proteins and they are found in all living cells.
Characteristics of Enzyme Catalysis
The following are some of the characteristics of enzyme catalysis:
1. Enzymes are proteins that catalyze biochemical reactions.
2. They are very specific in their catalytic activity.
3. Enzymes are very efficient in their catalytic activity.
4. not consumed in the catalytic reaction.
5. Enzymes can catalyze both biochemical reactions that occur in the cell and reactions that occur outside of the cell.
What are Colloids?
A colloid is a substance that is made up of tiny particles that are too small to see with the naked eye. These particles suspended in a liquid or gas.
Examples of Colloids
Some common examples of colloids include milk, blood, and fog.
Properties of Colloids
A colloid is a mixture in which one substance dispersed evenly throughout another substance. The dispersed substance called the dispersed phase, and the substance in which dispersed known as the dispersion medium.
Colloids typically distinguished from solutions by their greater size. A colloid has a dispersed phase that is larger than the size of the individual molecules in the dispersion medium. In a solution, the dispersed phase is smaller than the size of the individual molecules in the dispersion medium.
Colloids also typically distinguished from suspensions by their greater stability. A suspension is a mixture in which the dispersed phase not evenly distributed. Therefore the dispersed phase can form clumps or settle to the bottom of the dispersion medium. A colloid is stable, meaning that the dispersed phase remains evenly distributed.
Classification of Colloids and Suspensions
Colloids are suspensions of large particles in a liquid. The particles are too large to pass through the pores of a filter paper. Suspensions are colloids that are unstable and will eventually settle out.
What are Lyophilic Sols?
Lyophilic sols are solids that have dissolved in a solvent to form a solution, and then allowed to recrystallize. The crystals that form are more stable than the individual molecules of the solute and solvent.
What are Lyophobic Sols?
Lyophobic sols are sols that not attracted to other substances and also it will not dissolve in them.
Difference between Lyophilic and Lyophobic Sols
The main difference between lyophilic and lyophobic sols is that lyophilic sols attracted to water, while lyophobic sols repelled by it. Lyophilic sols typically composed of large particles that not soluble in water, while lyophobic sols made up of small particles that soluble in water.
Preparation of Colloids
A colloid is a suspension of small particles in a liquid. The particles in a colloid are too large to pass through the pores of a filter paper.
Colloids usually prepared by slowly adding a small amount of the solid to the liquid while stirring. The solid usually added to a cold liquid. This method prevents the solid from clumping together.
Applications of Colloids
Some common applications of colloids include paints, inks, and cosmetics. In the paint and ink industries, colloids used to create a variety of colors. The small particles in the colloid help to create a more even and consistent finish. Cosmetics also often contain colloidal particles, which help to create a smooth and even application.
Emulsions: What is Emulsion?
An emulsion is a mixture of two or more liquids that are not normally soluble in each other. Emulsions often created when one liquid suspended in another, such as in an oil-in-water emulsion. Emulsions also common in food and beverage products, such as mayonnaise and milk.
What is Emulsification?
Emulsification is the process of breaking down a liquid into droplets and dispersing it in another liquid. This often done with an emulsifier, which is a molecule that helps the two liquids mix together.
Mechanism of Emulsification
Emulsification is a process that breaks up a liquid into small droplets and disperses them in another liquid. This done by using a mechanical device or by shaking the liquids together. Emulsifiers added to the mixture to help keep the droplets from coalescing.
The mechanism of emulsification not fully understood, but it thought that the emulsifier molecules surround the droplets, preventing them from coming together. The emulsifier molecules also help to stabilize the emulsion, preventing it from breaking up.
Properties of Emulsions
An emulsion is a stable mixture of two or more liquids that are normally immiscible (unable to mix). Emulsions created when one liquid dispersed in another liquid in the form of small droplets. The dispersed liquid called the dispersed phase, and the continuous liquid called the continuous phase.
Emulsions have several properties that make them useful:
- They are stable.
- are easy to produce.
- They have a wide range of applications.
- are adaptable to a variety of conditions.
- They are relatively inexpensive to produce.
Types of Emulsions
Oil and water don’t naturally mix together. However, when an emulsifier added, the two can combined to form an emulsion. There are three main types of emulsions:
- Oil-in-Water Emulsion: The oil dispersed in the water. This is the most common type of emulsion.
- Water-in-Oil Emulsion: The water dispersed in the oil. Therefore this type is less common.
- Oil-in-Water-in-Oil Emulsion: This is the most complex type of emulsion. It rarely found in nature and usually created in a laboratory.
Adsorption’s Function in Surface Chemistry
Adsorption is a physical process that occurs when atoms, molecules, or ions from a gas or liquid phase adhere to the surface of a solid. Adsorption’s primary function in surface chemistry is to provide a means of transferring atoms, molecules, or ions from the gas or liquid phase to the surface of a solid.
What is the Definition of Catalysis?
The definition of catalysis is the increase in the rate of a chemical reaction due to the presence of a catalyst. Catalysts not consumed in the reaction and can used over and over again.
Catalysis comes in a variety of forms.
In biochemistry, enzymes are the most common catalysts. Enzymes are proteins that catalyze biochemical reactions. Inorganic catalysts include metal complexes and Lewis acids and bases. However organic catalysts include a variety of enzymes, including oxidoreductases, transferases, hydrolases, lyases, and isomerases.
What Exactly is a Colloid?
A colloid is a suspension of tiny particles in a liquid. In a true suspension, the particles are so small that they cannot seen with the naked eye. The particles in a colloid are large enough to seen, but they are still much smaller than the individual cells in a plant or animal.
Colloids are classified into Several Categories.
Some common categories of colloids are:
- solids dispersed in liquids (e.g. milk, paint, ink)
- liquids dispersed in liquids (e.g. salad dressing, ink)
- gases dispersed in liquids (e.g. carbonated drinks)
- solids dispersed in gases (e.g. snow, fog)
- liquids dispersed in solids (e.g. ice cream, Jello)
Surface Chemistry Emulsions
An emulsion is a dispersion of one liquid in another liquid. Emulsions are usually unstable, and the dispersed phase will eventually separate from the dispersion medium. Emulsions typically created when two liquids with different polarities mixed together. The nonpolar droplets of the first liquid will surround the polar droplets of the second liquid, and a stable emulsion will formed.
Some common emulsions are milk, mayonnaise, and salad dressing. In each of these cases, the oil dispersed in the water. The oil droplets surrounded by the polar water droplets, and the emulsion is stable. These droplets will eventually float to the top of the mixture, and the water will be on the bottom. This called an oil-in-water emulsion.
