A type of electrophilic aromatic substitution reaction to introduce an acyl group (R-C=O) in the aromatic ring resulting in aryl ketones. The reacting species are usually but not always -benzene (substituted or unsubstituted), an acyl halide and a Lewis Acid catalyst. In short, it can be stated as the acylation of the aromatic rings by the Friedel-Craft reaction method.
The activation energy (Ea) is the minimum amount of the extra energy absorbed by the reactant molecules from an energy source such as heat, light, etc., to attain the threshold value for effective collisions to occur and thereby to form an intermediate complex (active state) that finally results in product formation.
It can also be expressed as the difference between the threshold energy and the average kinetic energy possessed by the reactant molecules at the start of a chemical reaction.
Activation Energy = Threshold Energy – Average Kinetic Energy of the reactant molecules
The random collisions of the colloidal particles (dispersed phase) with molecules of the dispersion medium (colloidal sol) that results in a zig-zag movement of the colloidal particles, when observed under an ultramicroscope, is known as the Brownian Motion.
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Collision Frequency in chemical kinetics is defined as the number of collisions that take place per second per unit volume of the reaction mixture between two reactant molecules considered as hard spheres. It is represented as Z.
Collision theory is applicable only to bimolecular reactions mostly gases where the reactant molecules are considered as hard spheres that must collide with sufficient threshold energy and must be correctly oriented for the collision to be effective that results in the product formation.
The rate of the reaction, therefore, depends on the collision frequency, threshold energy, and the orientation (steric/probability) factor.
P- Steric Factor
ZAB - Collision Frequency
Ea - Activation energy
R - Gas Constant
T - Temperature
The compounds in which the central metal atom is linked to ligands (anions or neutral molecules) that donate its pair of electrons to form coordinate covalent bonds with the metal atom.
Dialysis is a process of diffusion of the colloidal particles through a parchment or an animal membrane to remove excess of an electrolyte or any soluble impurities (crystalloids).
Effective collisions are those that result in product formation due to an increase in the rate of a chemical reaction that occurs when the two reactant molecules are correctly oriented and have attained the threshold value (or the activation energy) at the time of the collision.
Depending on the nature of the charge (positive or negative) on the colloidal particles, its movement towards the electrode (cathode or anode) under the influence of an applied electric field is known as electrophoresis.
Electrophoresis proves the existence of charge on the colloidal particles and is used as a separation technique.
Few substances like gum, starch, gelatin, rubber have an inherent or a natural tendency to form colloidal sol on direct mixing with a suitable dispersion medium and are called intrinsic colloids. As they are solvent loving, they are also known as lyophilic colloids.