Solids dissolving rate

Dissolved Solids Boiling Pt/Freezing Point For Liquids/Solid Mixtures Bulk Density Total Solids Content Solids Size Distribution Suspended Solids Content Suspended Solids Settling Rate Dissolved Solids Content Free Water Content Oil and Grease Content Viscosity For Gases Density... 

The dissolution rate of a solid may be defined as dm/dt, where m is the mass of solid dissolved at time t. In a batch dissolution method, the analyzed concentration, cb, in the solution (if well stirred) is representative of the entire volume, V, of the dissolution medium, so that... 

The simplest solid-liquid reaction is the dissolution of a solid in a liquid. The rate at which a solid dissolves in a liquid depends on the particular crystallographic plane (face) exposed. The effect of crystallographic planes on dissolution is clear from the observation that spherical single crystals acquire polyhedral shapes while dissolving. In... 

A saturated solution of calcium fluoride in contact with solid CaF2 contains constant equilibrium concentrations of Ca2+ aq) and F (aq) because at equilibrium the ions crystallize at the same rate as the solid dissolves. 

The zero-order release rate of the elementary osmotic pump from t — 0 to time tx, when all the solids dissolve and the solute concentration begins to fall below saturation, can be defined as follows... 

The finer particles of the solid dissolve first as the solution becomes more concentrated the rate of solution grows slower, and it takes a very long time to dissolve the remaining coarser particles. Hence when a limited amount of solvent or reagent is used, as for example when copper is to be dissolved in a minimum amount of nitric acid, it is best to hold in reserve perhaps one-tenth of the reagent when the nine-tenths are almost exhausted and the reaction with the coarser particles has almost stopped, pour off the solution already obtained, and treat the small residue with the fresh acid held in reserve. 

Extraction Rates. The design of large-scale solvent extraction vessels must accommodate the rate at which equilibrium is attained between the free miscella flowing past the solid particles and the miscella absorbed within the solids. Attainment of equilibrium may be quite slow, particularly as the oil content of the solid material drops to low levels. Investigations show that the rate at which equilibrium is approached (in effect, the extraction rate) is influenced by many factors, including the intrinsic capacity for diffusion of solvent and oil, which is determined primarily by the viscosities of the two the size, the shape, and the internal structure of the solid particles and, at low oil levels in the solids, the rate at which the solvent dissolves nontriglyceride substances that are soluble but dissolve less readily than the triglycerides. 

D) Action of Alcoholic Alkali. Use alcoholic potassium hydroxide solution containing 30 g of the solid dissolved in 90 ml of 90 per cent methyl or ethyl alcohol. Place 3 ml of the alkali solution in each of three tubes. Add to seperate respective tubes 1 ml of n-amyl bromide, amyl bromide, and benzyl chloride. Shake gently for a minute, cork, label each tube, and set aside for the next laboratory period. If it is desired to observe the rate at which the halides react, examine after 30 minutes the extent of the reaction as judged by the amount of potassium halide formed. After 24 hours add 3 ml of water, shake, and allow to separate. Note the odor. With a clean dropper or pipette withdraw two drops from each and test with bromine water and dilute permanganate. n -Amyl bromide yields a considerable amoimt of ether, but little olefin. Benzyl chloride yields entirely carbinol. Put the contents of the three tubes into bottles provided by the instructor. 

Many compounds and salts are sensitive to the presence of water vapour or moisture. When compounds interact with moisture, they retain the water by either bulk or surface adsorption, capillary condensation, chemical reaction and, in extreme cases, a solution (deliquescence). Deliquescence is where a solid dissolves and saturates a thin film of water on its surface. It has been shown that when moisture is absorbed to the extent that deliquescence takes place at a certain critical relative humidity, the liquid film surrounding the solid is saturated. This process is dictated by vapour diffusion and heat transport rates (Kontny et al. 1987). 

Figure 7.2 summarizes the relative weathering rates of major minerals in igneous and metamorphic rocks. Actual weathering rates depend also on soil temperature and moisture, particle size, and planes of physical weakness (cleavage) in the crystal. The effect of moisture includes both the flow rate of soil solution past mineral surfaces and the composition of the solution. Solids dissolve more slowly if the solution already contains their constituent ions. High electrolyte concentrations, on the other hand, can maintain higher ion concentrations at equilibrium because of lower activity coefficients and because of complex-ion and ion-pair formation. 

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