Equilibrium insoluble solid

Composition Uiagrants In its elemental form, a leaching system consists of three components inert, insoluble solids a single non-adsorbed solute, which may be liqmd or solid and a single solvent. Thus, it is a ternaiy system, albeit an unusual one, as already mentioned, by virtue of the total mutual Mnsolubility of two of the phases and the simple nature of equilibrium. 

For the agitator and thickener 1, the underflow, of composition x, will contain insoluble solid mixed with solution of the same concentration as that in the overflow yi, on the assumption that equilibrium conditions are reached in the thickener. All such mixtures of solution and insoluble solid are represented by compositions on the fine Oyi. As this stream is an underflow, its composition must also be given by a point on the line EF. Thus xi is given by the point of intersection of EF and Oyi. The composition y2 of the overflow stream from thickener 2 must lie on the hypotenuse of the triangle and also on the line through points A and xi. The composition y2 is therefore determined. In this manner it is possible to find the compositions of all the streams in the system. The procedure is repeated until the amount of solute in the underflow has been reduced to a... 

The moisture content of a material is usually expressed in terms of its water content as a percentage of the mass of the dry material, though moisture content is sometimes expressed on a wet basis, as in Example 16.3. If a material is exposed to air at a given temperature and humidity, the material will either lose or gain water until an equilibrium condition is established. This equilibrium moisture content varies widely with the moisture content and the temperature of the air, as shown in Figure 16.1. A non-porous insoluble solid, such as sand or china clay, has an equilibrium moisture content approaching zero... 

Wetting Parameters in the Detergency Equation. The detergency system has three interfaces which have three interfacial tensions at equilibrium with all three phases Ksw> Yfs and Yfw When only two phases are in equilibrium, three other surface tensions are possible Ysw> Yfs> Yfw (however, when the fiber is an insoluble solid, Ysw Y w> Ysw will be... 

If there is introduced into the solution from some other source an ion that is in common with an ion of the insoluble solid, the chemical equilibrium is shifted to the left, and the solubility of that solid will be greatly decreased from what it is in pure water. This is called the 11 common-ion effect." This effect is important in gravimetric analysis, where one wishes to precipitate essentially all of the ion being analyzed for, by adding an excess of the "common-ion" precipitating reagent. There is a practical limit to the excess, however, which involves such factors as purity of precipitate and possibility of complex formation. You can calculate the solubility under a variety of conditions, as illustrated in the following problem. 

Phase Equilibrium between Mutually Insoluble Solids.—In the... 

Zn2+ + 4NH3 -> Zn(NH3)42+ or Zn2+ + NH3 + 2HzO - Zn(OH)2 + NH4+. There are two possible outcomes here. One is the formation of a complex ion and the other is the formation of insoluble zinc hydroxide. Either would be given credit. On this problem, remember the ammonia and water solution is in equilibrium and can be written as NH3 + H20, or NH4+ + OH. Either is considered correct. The implications on the reaction are when the ammonia is in the NH3 state, the formation of the complex is favored. The other, NH4+ state, frees the hydroxide ions to form the insoluble solid. 

In solution, an equilibrium in which the very soluble cis isomer is favored is established between the two isomers. However, the small solubility of the trans isomer causes its precipitation as evaporation proceeds. If evaporation proceeds too far, the precipitate of the trans isomer is contaminated by increasing amounts of the cis isomer. To test for the purity of the trans isomer, a few drops of dilute aqueous ammonia are added to a few milligrams of the product on a filter paper. If the trans isomer is pure, a light-brown, insoluble solid forms. If the cis isomer is present, a deep-green solution forms and spreads on the paper. 

Inorganic phosphate ligands are important with respect to the behavior of actinides in the environment and as potential waste forms. There have been a number of experimental studies to determine the equilibrium constants in the actinide-phosphoric acid system, but they have been complicated by the formation of relatively insoluble solid phases and the formation of ternary actinide complexes in solution. 

The equilibrium of the enzyme acylation reaction can be shifted towards the synthesis of the amide by precipitation of the acylated product formed (Fig. 6). The racemic ethyl 3-amino-5-(trimethylsilyl)-4-pentynoate 3 is an insoluble liquid, whereas the (R)-phenylacetamide 10 is an insoluble solid. The racemic ethyl 3-amino-5-(trimethylsilyl)-4-pentynoate 3 was added to dilute hydrochloric acid. The pH of the reaction medium was then adjusted to 6. Phenylacetic acid (2 equiv.) was added and the pH of the medium was readjusted to 6. Soluble PGA (50 units/100 mg of racemic amine) was added, and the reaction was stirred at room temperature. After completion of the reaction, the pH of the reaction mixture was adjusted to 4. Filtration of the reaction mixture gave (R)-amide 10 in quantitative yield. Chiral HPLC analysis of this isolated amide showed the absence of (S)-amide. The pH of the filtrate was raised to 8, and the filtrate was extracted with ethyl acetate to obtain (S)-amine 11 (yield 90%) (Fig. 6). The chiral HPLC analysis indicated an R S ratio of 2 98. 

In our spreadsheet exercise we will consider a textbook example, the solubility of HgS as a function of pH, in a solution in equilibrium with solid HgS that contains no other sources of mercury and sulfur. HgS is quite insoluble, with a reported solubility product of 5 X 10 54 M2. The case is complicated by the fact that the two participant ions, Hg2+and S2 , are both involved in acid-base equilibria. For Hg2+these are the successive formation of three hydroxy complexes HgOH+, Hg(OH)2, and Hg(OH)3 , for S2 the consecutive... 

Generally, the solids are not structurally homogeneous, but the solid and liquid nevertheless will be called phases and leaching will be treated as a two-phase, mass transfer process- The solid consists of a matrix of insoluble solids, the mare, and the occluded solution. It may also contain undissolved solute and a nonextractable secondary phase, for example, coffee oil in water-soaked coffee grounds. This secondary phase is treated as part of the mate. Dimensionless parameters that can affect solnta transfer include the solute equilibrium distribution coefficients, m and M tha Pick number, v the strippirg factor, a the Biot number, Bi and the Peclet number, Be. These parameters are defined more precisely in the Notation section. 

D13. Batch leaching will be similar to a batch extraction, and the equations developed in Section 13.6 can be adapted when the solution is dilute or there is an insoluble solid matrix. We have 12.5 liters of pure water that we will use to leach 10.0 liter of wet sugar cane solids. Equilibrium data... 

D14. Barium sulfide is produced by reacting barium sulfate ore with coal. The result is barium black ash, which is BaS plus insoluble solids. Since BaS is soluble in water, it can be leached out with water. In thickeners the insoluble solids in the underflow typically carry with them 1.5 kg liquid per kg insoluble solids. At equilibrium the overflow and underflow liquids have the same BaS concentrations fTreybal. 19801. We want to process 350 kg/h of insoluble solids plus its associated underflow liquid containing 0.20 mass fraction BaS. Use a countercurrent system with 2075 kg/h of water as solvent. The entering water is pure. We desire the outlet underflow liquid to be 0.00001 mass fraction BaS. Find ... 

An insoluble solid acts only at its points of contact with a solution, to a less extent by the amount dissolved increasing the solid has little effect (I, iv). Gay-Lussac recognised that the amount of solid has no influence on the solubility. Berthollet (I, iv, S, 7 x) was clear that it is the quantities in the equilibrium state, not the initial quantities, which determine the extent of action. 

The Dissolution of Mg(OH)2 by Acid animation (eChapter 17.5) shows how the relatively insoluble solid, Mg(OH)2, can be made more soluble in water by the addition of acid, (a) Write the net ionic equation for the process by which magnesium hydroxide dissolves in neutral water, (b) Write the net ionic equation for the combination of two hydronium ions with two hydroxide ions, (c) Show foat foe net ionic equations in parts (a) and (b) add to give foe overall net ionic equation shown in the animation, (d) Calculate the equilibrium constant for the process represented by the overall net ionic equation (i.e., dissolution of magnesium hydroxide in aqueous acid), (e) Determine the solubility of magnesium hydroxide in 0.010 M HCl. 

Leached sMis kg oil/kg insoluble solid — 0.00S/0.99S = 0.00S03. By interpolation in the equilibrium data, — 1.718 kg solid/kg soln. 

The usual situation, true for the first three cases, is that in which the reactant and product solids are mutually insoluble. Langmuir [146] pointed out that such reactions undoubtedly occur at the linear interface between the two solid phases. The rate of reaction will thus be small when either solid phase is practically absent. Moreover, since both forward and reverse rates will depend on the amount of this common solid-solid interface, its extent cancels out at equilibrium, in harmony with the thermodynamic conclusion that for the reactions such as Eqs. VII-24 to VII-27 the equilibrium constant is given simply by the gas pressure and does not involve the amounts of the two solid phases. 

In the phase equilibrium between a pure solid (or a liquid) and its vapour, the addition of other gases, as long as they are insoluble in the solid or liquid, has negligible effect on the partial pressure of the vapour. 

Precipitation involves the alteration of the ionic equilibrium to produce insoluble precipitates. To remove the sediment, chemical precipitation is allied with solids separation processes such as filtration. Undesirable metal ions and anions are commonly removed from waste streams by converting them to an insoluble form. The process is sometimes preceded by chemical reduction of the metal ions to a form that can be precipitated more easily. Chemical equilibrium can be affected by a variety of means to change the solubility of certain compounds. For e.xample, precipitation can be induced by alkaline agents, sulfides, sulfates, and carbonates. Precipitation with chemicals is a common waste stream treatment process and is effective and reliable. The treatment of sludges is covered next. 

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