Pressure Swing Adsorption ( Psa ) : Application Of Interfacial Phenomenon

Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a semi-permeable(selectively permeable) membrane is osmosis. Semi-permeable means that some molecules can move through the membrane while others can not. Diffusion and Osmosis are passive forms of transport requiring no energy. Active Transport utilizes energy in the form of ATP. Water is a solvent that can dissolve a number of substances more than any other substance. Wherever water goes, through the ground or a body, it takes along valuable molecules. Water’s chemical composition causes it to be attracted to many different molecules and be attracted so strongly it disrupts the forces and dissolves it. Water can pass through the semipermeable membrane without any help but can change the solution, on the other side of the cell membrane, depending on how much it diffuses in and out.

Whenever a monolayer is attached to a metal surface, the wetting properties and behavior can be significantly affected (Yuan & Lee, 15). In practice, densely-packed self-assembled monolayers (SAMs) can be used to modify the macroscopic properties of a solid surface (Dilimon et al. 202). Changes in wetting properties occur due to changes in the angle made by a liquid droplet whenever it is in contact with the surface. This phenomenon is significant in several contexts for example, in industrial contexts: this property is used to evaluate the cleanliness of semiconductor wafers. In such contexts, contact angles measurements are widely used. Control of this property is also useful during penetration of insecticides or pesticides into plants, and waterproofing of materials (Yuan & Lee, 25). While the former focuses on maximization of wetting, the latter case seeks to minimize liquid-induced wetting (Yuan & Lee, 28).

Attractions between water and other molecules, which is adhesion, is also possible because of the polarity as well. In relation to hydrogen bonds, water’s high specific heat is changed when hydrogen bonds are made or broken. When a hydrogen bond breaks, heat is absorbed whereas when a hydrogen bond forms, heat is released. In addition to HSH, ice is able to float in liquid water because hydrogen bonds in ice is more structured than in water, making the ice less dense. Also, water is a versatile solvent because of its polarity, which helps it form hydrogen bonds (mentioned above). The structure of water molecules also affects the dissociation of water, where H2O breaks into H+ and OH- due to the polarity of the

Adsorption chromatography occurs when “one substance form[s] some sort of bonds to the surface of another one”, creating intermolecular forces between the two substances (Chemguide). For thin layer chromatography, the components of the mixture are adsorbed onto the stationary phase that covers the plate (Chemguide). The more polar a substance is, the more strongly adsorbed it is (Chemguide) and the strong intermolecular forces then result in a slower rate of migration with respect to the moving phase. As the solvent touches the TLC plate, the solute (mixture) is allowed to move up the TLC plate

Surface Tension: The measure of how difficult it is to stretch or break the surface of a liquid.

When an object falls onto the surface, it has to push the water molecules apart. If the effect of the weight of the object is insufficient to match the attractive forces between molecules in the surface layer, the object will not enter the surface.

The more molecules that are able to escape into the vapor, the greater the decrease in temperature due to evaporative cooling. Thus, a larger negative ΔT corresponds to a substance in which the IMFs are weak.

Diffusion, the spontaneous movement of molecule from an area of higher concentration to an area of lower concentration, and

Data from previous studies suggest that the inactive sHSP takes on the oligomer conformation Upon stress, these oligomers assemble into active dimeric species, exposing previously inaccessible hydrophobic surfaces that can then interact with nonpolar patches on the misfolded substrate, capturing them in large complexes. The sHSP-substrate complexes maintain the substrate in a folding-competent state for extended periods of time. Biologically this is of utmost importance since it is

(Click Slide) Due to adhesion, capillary action occurs in plants. Water absorbed from the roots sticks to the walls of xylem vessels in plants, and cause an upward motion. Sometimes, you may see that when you wet a paper towel, the water quick travels up the towel. Capillary action occurs when adhesive forces are stronger than cohesive forces.

osmosis- a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane

represents a type of potential energy that accounts for the both concentration and the membrane

Many reactions that exist in nature involve a double displacement between ions and reactants with solvents. A bimolecular nucleophilic substitution, or SN2 reaction, involves a nucleophilic attack on a substrate and the departure of a leaving group. A nucleophile is a compound or ion that donates electrons to promote bond formation (Caldwell, 1984). In order for a leaving group in a compound to leave, it must possess the characteristics of a weak base and be able to occupy electrons. Several factors affect the rate and favorability of such reaction, such as (Bateman, 1940). In addition, the substrate that is attacked by the nucleophile is commonly an unhindered primary substrate to allow the reaction to occur quicker. An SN2 reaction follows the second-order rate law.

Note 1: These are intermolecular forces of attraction so they occur OUTSIDE of the molecules!

Diffusion is the passage of solute molecules from an area of high concentration to an area of low concentration (Campbell & Reece, 2005). An example is ammonia diffusing throughout a room. A solute is one of two components in a chemical solution. The solute is the substance dissolved in the solution. The solvent, the other component, is any liquid in which the solute can be dissolved (Anderson, 2002). Diffusion requires little or no energy because molecules are always randomly moving; this is due to their kinetic energy. Diffusion occurs only when there is an imbalance in the areas of