Download now kerala plus two chemistry important questions. Thus, an increase in the ionic strength is results in a smaller debye length, more compacted double layer and a smaller barrier to aggregation. This rule describes an interesting situation of the aggregation of charged colloidal particles in the presence of the multivalent coions. Cleansing action of detergents involves the formation of micelles. Out of bacl2 and kcl, which one is more effective in. Adsorption the accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed adsorption. It states that greater the valency of the occulating ion of the electrolyte, the faster is the coagulation. Aggregation behavior of aqueous cellulose nanocrystals. Download kerala board plus two chemistry important question pdf. Surface chemistry dav centenary public school, paschim enclave, new delhi 87. How many octahedral voids are present in fcc crystal. Karnataka 2nd puc syllabus 2020 2021 12th class exam.
According to the hardy schulze rule, the greater the valency of a flocculating ion, the greater will its coagulating power. The greater is the valence of the oppositely charged ion of the electrolyte added to a colloidal solution, the faster is the coagulation of the colloidal solution. Greater is the valency of the coagulating or the flocculating ion. The schulze hardy rule can be derived from dlvo theory as well. Calculate the mass of a nonvolatile solute molar mass40 gmol which should. Macroions with increased surface charge density follow the schulze hardy rule with an increased exponent. Other mechanisms of colloid stabilization are equally possible, particularly, involving polymers. Hardy schulze law states that the greater the valence of the flocculating ion added, the greater is its power to cause precipitation. What modification can you suggest in the hardyschulze law.
The coagulating power of an ion depend on both magnitude and sign of the charge of the ion. Hardy schulze rule this rule states that the precipitating effect of an ion on the dispersed phase of opposite charge increases with the valency of the ion. The required amount of electrolyte for the coagulation of a definite quantity of colloidal solution is dependent on the valency of the coagulating ion which is the. These are formed when the concentration of detergents becomes equal to cmc.
Derivation of the inverse schulzehardy rule arxiv vanity. This law takes into consideration only the charge carried by an ion, not its size. The schulze hardy sh rule is an empirical rule, stating that the coagulation concentration c cr of hydrophobic sols decreases very strongly with the valency z of the counterion. Hello students, in this video i explain coagulation, flocculation, precipitation, hardy schulze rule, protective colloid. Schulze hardy rule this rule is valid only for system in which there is no interaction between electrolyte and ion of double layer of particle surface. According to the schulzehardy rule, known since about. Detergents with low cmc are more economical to use. Coagulationflocculationprecipitation hardy schulze. Coagulation is a process which involves coming together of colloidal particles so as to change into large sized particles which ultimately settle as a precipitate or. Coagulation, hardy schulze rule, stability of colloids and origin of charge on colloids, electrokinetic potential, adsorption, various types of adsorption isotherms, catalysis, enzyme catalysis michelismenten equation. What is hardy schulze rule homework help mycbseguide. Rediscovering the schulzehardy rule in competitive. The inverse schulze hardy rule was recently proposed based on experimental observations. The coagulation capacity of different electrolytes is different.
Hardy schultz rule the coagulation of a colloidal solution by an electrolyte does not take place until the added electrolyte has certain minimum concentration in the solution. Influence of valency of ion on aggregation of lyophobic particle can be correlated to zeta potential and sedimentation volume hofmeister of lyotropic rule apply to hydrophilic. Expanding the schulzehardy rule and the hofmeister series to. Thus, hardy schulze law can be modified in terms of the polarising power of the flocculating ion. An expansion of schulze hardy rule and hofmeister series to nanometer. It means that coagulation power of an electrolyte is directly proportional to the fourth power of the valency of the effective ion i. The commonly presented derivation of this rule assumes symmetric electrolytes and highly charged particles.
The smaller the size of an ion, the more will be its polarising power. It states that greater the value of the flocculating ion added, the greater is its power to cause precipitation. The effective ions of the electrolyte in bringing about coagulation are those which carry charge opposite to that of the. Chemistry handbooksurface chemistry handbook pdf iit. Request pdf expanding the schulzehardy rule and the hofmeister series to nanometerscaled hydrophilic macroions the.
Hardy schulze rule,protective colloid, gold number online chemistry tutorial iit, cbse chemistry, icse chemistry, engineering and medical chemistry entrance exams, chemistry viva, chemistry job interviews. Home 12th class 12th class chemistry previous paper setc jammu jkbose pdf 12th class chemistry previous paper setc jammu jkbose pdf jkbose july 19, 2017. The effective ions of the electrolyte in bringing about coagulation are those which carry charge opposite to that of the colloidal particles. Surface chemistry coagulation and hardy schulze law. The schulze hardy rule suggests a strong dependence of the critical coagulation concentration ccc on the ionic valence. A reassessment of the applicability of the dlvo theory as. This rule is addressed theoretically and confronted with recent experimental results.
It stems from the end of the nineteenth century, and its qualitative validity has since been confirmed over and again for a variety of sols and conditions. Explain smelting with chemical equations in the extraction of. Following solutions were prepared by mixing different volumes of naoh and hcl of different concentrations. Hardy schulze rule application of colloids average rate of reaction instantaneous rate of reaction concentration of reactants, temperature, catalyst, nature of reactants, pressure gases, presence of light, surface area of the reactants rate law and specific rate constant order and molecularity zero order reactions first order reactions.
The schulze hardy rule 1 and the low charge dh limit 3 were both derived theoretically. Greater is the valency of coagulating ion added, the greater is its power to cause precipitation. Coagulation or flocculation or precipitation, chemistry. Cations in macroionic solutions follows the classical cationic hofmeister series. The detailed karnataka 12th class syllabus 2020 2021 is listed in this page, verify karnataka puc 2nd year exam pattern to know the total number of questions, marking scheme, exam duration and model of question papers. On the other hand, the inverse schulze hardy rule was only given as an empirical dependence based on experimental observations. Hardy schulze rule,protective colloid, gold number. A reassessment of the applicability of the dlvo theory as an explanation for the schulze hardy rule for colloid aggregation simon berners hall, john ralph duffield, and david raymond williams1 school of chemistry and applied chemistry, university of wales college of cardiff, p. Expanding the schulzehardy rule and the hofmeister series. Specifically, it can be shown that the critical coagulation concentration is inversely proportional to the coion valence. According to hardy schulze rule, greater the valency of the active ion or flocculating ion, greater will be its coagulating powerthus, hardy schulze law state. One of the first surprising generalizations regarding colloid stability 18801900 was that the critical electrolyte concentration required to flocculate cfc a variety of positive and negative colloids decreased as z. Nature volume 190, pages6896901961cite this article. Hofmeister schulze hardy rule coarsegrained model saxs introduction.
According to hardyschulze rule, greater the valency of the active ion or flocculating ion, greater will be its coagulating power. Adsorbed or grafted polymers may form a protective layer around the particles, induce steric repulsive forces. Raman effect, stokes and antistokes lines and their intensity difference. Or differentiate octahedral and tetrahedral voids with examples. How many litres of water must be added to 1 litre of an aqueous solution of hcl with a ph of 1 to create an aqueous solution with ph of 2. Ask questions, doubts, problems and we will help you. It depends upon the valency of the active ion are called flocculating ion, which is the ion carrying charge opposite to the charge on the colloidal particles. Thus, the modified hardy schulze law can be stated as the greater the polarising power of the flocculating ion added, the greater is its power to cause precipitation. Box 912, cardiff cf1 3tb, united kingdom received march 12, 1990. The molecular species or substance, which concentrates or accumulates at the surface is termed adsorbate and the material on the surface of which the adsorption takes place is called adsorbent. The higher the valency of the flocculating ion, the greater is its precipitating power. Notice that for the same concentrations of ions, the ionic strength increases with the square of the ion charge. Coagulation by multivalent counterions and the schulze.
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