Energy barrier of proton transfer at ice surfaces
... reversibility predicts a relationship, kf = 4kb共=k兲, for the overall reaction. This relationship holds independent of the H/D exchange mechanism and the hydrogen bonding structure of the system. As a first-order approximation, we assume that H/D exchange reaction is solely responsible for the change ...
... reversibility predicts a relationship, kf = 4kb共=k兲, for the overall reaction. This relationship holds independent of the H/D exchange mechanism and the hydrogen bonding structure of the system. As a first-order approximation, we assume that H/D exchange reaction is solely responsible for the change ...
Gases - HCC Learning Web
... take these deviations from ideal behavior into account. • The corrected ideal-gas equation is known as the van der Waals equation. • The pressure adjustment is due to the fact that molecules attract and repel each other. • The volume adjustment is due to the fact that molecules occupy some space on ...
... take these deviations from ideal behavior into account. • The corrected ideal-gas equation is known as the van der Waals equation. • The pressure adjustment is due to the fact that molecules attract and repel each other. • The volume adjustment is due to the fact that molecules occupy some space on ...
Indian Journal of Chemistry
... Novel CrF3 supported palladium catalysts have been prepared through two different precursors i.e. dichlorobistriphenyl-phosphine palladium (DCTPPP) and PdCl2 for the hydrodechlorination of CFC-12. These catalysts exhibited improved catalytic activities in hydrodechlorination of CFC-12 as compared wi ...
... Novel CrF3 supported palladium catalysts have been prepared through two different precursors i.e. dichlorobistriphenyl-phosphine palladium (DCTPPP) and PdCl2 for the hydrodechlorination of CFC-12. These catalysts exhibited improved catalytic activities in hydrodechlorination of CFC-12 as compared wi ...
Equilibrium Chemistry
... chemicals and solid surfaces and are important in both natural (air, soil, surface- and groundwater) and engineered (water and wastewater treatment) systems. Adsorption is defined as the physicochemical process in which a substance accumulates at a solid-liquid interface. Adsorption is a physical ph ...
... chemicals and solid surfaces and are important in both natural (air, soil, surface- and groundwater) and engineered (water and wastewater treatment) systems. Adsorption is defined as the physicochemical process in which a substance accumulates at a solid-liquid interface. Adsorption is a physical ph ...
Folie 1
... perfect gases is the sum of the partial pressures of the gases. The partial pressure of a gas is the pressure that it would exert if it occupied the container alone. If the partial pressure of a gas A is pA, that of a perfect gas B is pB, and so on, then the partial pressure when all the gases occup ...
... perfect gases is the sum of the partial pressures of the gases. The partial pressure of a gas is the pressure that it would exert if it occupied the container alone. If the partial pressure of a gas A is pA, that of a perfect gas B is pB, and so on, then the partial pressure when all the gases occup ...
Manual Physical Chemistry III
... is much higher. On the other hand, these cohesive forces are not strong enough to result into the fixed position of molecules that can be seen in solid matter. Liquids do not keep a fixed shape, but adapt the shape of a container. Attractive cohesive forces are short range forces which are based on ...
... is much higher. On the other hand, these cohesive forces are not strong enough to result into the fixed position of molecules that can be seen in solid matter. Liquids do not keep a fixed shape, but adapt the shape of a container. Attractive cohesive forces are short range forces which are based on ...
Reaction of tungsten anion clusters with molecular and atomic
... which dissociation of nitrogen is thermodynamically more favored with respect to the molecular chemisorption.18,19 Our experimental observations that molecular nitrogen is more stable than atomic nitrogen on W⫺ n with n⫽6 – 8 can be rationalized by an electronic model, in which metal to adsorbate ch ...
... which dissociation of nitrogen is thermodynamically more favored with respect to the molecular chemisorption.18,19 Our experimental observations that molecular nitrogen is more stable than atomic nitrogen on W⫺ n with n⫽6 – 8 can be rationalized by an electronic model, in which metal to adsorbate ch ...
THE KINETICS OF CHEMICAL REACTIONS: SINGLE
... any cooperativity among molecules would disappear as the number of molecules per unit volume becomes smaller and smaller and, consequently, the average distance between the molecules increases. Since Eq. 2 is known to be satisfied even for very dilute solutions of molecules, the hypothesis that the ...
... any cooperativity among molecules would disappear as the number of molecules per unit volume becomes smaller and smaller and, consequently, the average distance between the molecules increases. Since Eq. 2 is known to be satisfied even for very dilute solutions of molecules, the hypothesis that the ...
Synthesis gas purification.
... NiS þ 4 CO þ H2 () NiðCOÞ4 þ H2 S Equilibrium data were reported by Higman and van der Burgt [3]. From these data, it can be seen that ...
... NiS þ 4 CO þ H2 () NiðCOÞ4 þ H2 S Equilibrium data were reported by Higman and van der Burgt [3]. From these data, it can be seen that ...
Chemical Thermodynamics : Georg Duesberg
... Isothermal atmosphere Mgh is the gravitational potential energy. We will often see properties varying in proportion to exp(-E/RT) = exp(-ε/kBT) where E is a form of molar energy (ε is a molecular energy) because these are examples of "Boltzmann distributions". Chapter 1 : Slide 17 Chemical Thermodyn ...
... Isothermal atmosphere Mgh is the gravitational potential energy. We will often see properties varying in proportion to exp(-E/RT) = exp(-ε/kBT) where E is a form of molar energy (ε is a molecular energy) because these are examples of "Boltzmann distributions". Chapter 1 : Slide 17 Chemical Thermodyn ...
Noi strategii de realizare a unor bio
... To determine a specific type of SAM, formed by adsorption of molecules mixed (mSAM) or a homogenous monolayer molecules, the simple (hSAM), suitable with the electrochemical direct detection of the protein h FABP, the nano structurated gold surfaces were functionalized with a mixture solution of thi ...
... To determine a specific type of SAM, formed by adsorption of molecules mixed (mSAM) or a homogenous monolayer molecules, the simple (hSAM), suitable with the electrochemical direct detection of the protein h FABP, the nano structurated gold surfaces were functionalized with a mixture solution of thi ...
Chemical equilibrium and the kinetic theory of gases
... The partial pressures (in bar) of H2O, CO and CO2 in an equilibrium reached in a reaction vessel at 700 K were: H2O: 0.72; CO: 1.21; CO2: 2.10. Calculate the partial pressure of H2. 2 Esters, used in the food industry as flavourings, are manufactured by reacting carboxylic acids and alcohols. The e ...
... The partial pressures (in bar) of H2O, CO and CO2 in an equilibrium reached in a reaction vessel at 700 K were: H2O: 0.72; CO: 1.21; CO2: 2.10. Calculate the partial pressure of H2. 2 Esters, used in the food industry as flavourings, are manufactured by reacting carboxylic acids and alcohols. The e ...
The impact of ionic strength on the adsorption
... Moreover, a number of studies have arbitrarily assigned electrostatic correction factors for data collected at a single ionic strength (e.g., [8,15]). Other studies have focused on bacterial cell wall components which, although useful, may not be entirely representative of the bacterial surface elec ...
... Moreover, a number of studies have arbitrarily assigned electrostatic correction factors for data collected at a single ionic strength (e.g., [8,15]). Other studies have focused on bacterial cell wall components which, although useful, may not be entirely representative of the bacterial surface elec ...
Adsorption
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) permeates or is dissolved by a liquid or solid (the absorbent). Adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of it. Adsorption is a surface phenomenon.Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.Adsorption is present in many natural, physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increase storage capacity of carbide-derived carbons, and water purification. Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Pharmaceutical industry applications, which use adsorption as a means to prolong neurological exposure to specific drugs or parts thereof, are lesser known.However, it should be remarked that the distinction between adsorption and absorption vanishes as we go from perfectly crystalline macroscopic materials to porous/structured materials, aggregates and composites made out of increasingly smaller grains, viz., micron-sized particles to nanoparticles, sub-nano particles and finally molecules (or atoms). In such nano-composites, the internal surface area of particulate matter is very large. Then the adsorption on internal surfaces simply becomes absorption when viewed from the bulk. Then the distinction between adsorption and absorption vanishes. On the other hand, the distinction is clearest between bulk solids without internal structure, but having only surfaces where only adsorption can occur on the outer surfaces, and nanocomposites or aggregates with internal structure where absorption by the host material is simply adsorption on internal surfaces of the host material. As an example, we may consider a crystalline piece of silicon dioxide (quartz) which can adsorb water molecules on its surface. However, if the quartz is ground into very fine sand, the pile of sand (an aggregate) has a very large internal surface area. A very large amount of water can be adsorbed by the ""internal"" surfaces of the grains in the pile of sand, and this absorption is simply ""internal adsorption. If water is made to flow thorugh such a pile of sand, ions and toxins in the water may be preferentially adsorbed by the surfaces of the grains of sand, providing a simple, well-known water purification application.The word ""adsorption"" was coined in 1881 by German physicist Heinrich Kayser (1853-1940).