Problems Barium chloride

These rosin-based sizes, whether paste, Hquid, or emulsions, can be used to size all grades of paper that are produced at acid pH. The latter include bleached or unbleached kraft Hnerboard and bag paper, bleached printing and writing grades, and cylinder board. In addition, polyaluminum compounds have been used in place of alum, most notably, polyaluminum chloride (48), which can reduce barium deposits where these have been a problem. The barium chloride by-product is more water-soluble than barium sulfate. Other polyaluminum compounds such as polyhydroxylated forms of alum and polyaluminum siHcosulfate have been evaluated as alum replacements. 

In order to suppress interferences due to the presence of inorganic species and reliably determine the proteinaceous composition of the sample, a clean-up step has often been introduced in the analytical procedure. This step may include the extraction of the proteinaceous matter by an ammonia solution [8], the use of a cation-exchange resin [8,55], a chelating agent [9,41,44], the use of a Cig resin or the use of barium chloride solution to suppress sulfates [10,81,82]. Table 9.1 reports the methods used to overcome such problems. 

Practice Problem 1 0.30 How many moles of barium ions and how many grams of barium chloride would be required to produce 6.11 g of barium sulfate I... 

The melting point of cobalt is 1495°C, and that of barium chloride is 963°C. Rank the four substances in problem 27 from lowest to highest in melting point. 

Two different approaches to the problem of releasing deposited alloy films have been assessed. One is to use a polymeric substrate that can be dissolved in a suitable solvent, while the other is to choose a solid substrate to which the deposited film adheres very poorly so that it is easily lifted off. Yet another procedure is to coat a polymeric film such as Kapton with a water-soluble release agent such as sodium iodide or barium chloride. There are many other such possibilities. 

But here a problem was created. It was reasonable to suppose that when a substance dissolved in, let us say, water it broke up into separate molecules. Sure enough, in the case of non-electrolytes such as sugar, the depression of the freezing point fit that assumption. However, when an electrolyte like common salt (NaCl) was dissolved, the depression of the freezing point was twice as great as it should have been. The number of particles present was twice the number of salt molecules. If barium chloride (BaCl2) was dissolved, the number of particles present was three times as great as the number of molecules. 

A more subtle problem is to maximize the yield of a reaction that could be carried out in any of a number of media. Should a reaction be done in a solvent in which the desired product is most or least soluble, for instance The answer is not immediately clear. In fact one must say, It depends. If the reaction is between ions of two soluble salts, the product will precipitate out of solution if it is insoluble. For example, a reaction mixture containing barium, silver, chloride, and nitrate ions will precipitate insoluble silver chloride if the solvent is water, but in liquid ammonia the precipitate is barium chloride. Another example, from organic chemistry, described by Collard et al. (2001) as an experiment suitable for an undergraduate laboratory, is the dehydra-tive condensation of benzaldehyde with pentaerythritol in aqueous acid to yield the cyclic acetal, 5,5-bis(hydroxymethyl)-2-phenyl-l,3-dioxane, 1 ... 

Let s take the example of the mixing of 50 ml of a 3 x 10 mol/L barium chloride solution with 100 ml of a 4.5 x 10 mol/L sodium sulfate solution. The problem is to determine the fraction of barium precipitated. Let s call P the number of moles of precipitated barium sulfate per liter of solution. The mass balance relations on Ba +, 504 together with the solubility-product expression provide a system of three equations in three unknowns [Ba +], [804 ], and P ... 

For example, let s consider a solution containing 10 mol/L of barium chloride and 10 mol/L of strontium chloride. A saturated solution of sodium sulfate is added to it. The problem is to calculate the concentration of the remaining ion (the most insoluble) when the second begins to precipitate. The solubility products are /fs(BaS04) = 1.1 X 10 ° and /fs(SrS04) = 2.8 x 10 . An examination of the solubility products shows that barium ions precipitate first. Just at the beginning of the strontium precipitation, both solubility products are satisfied simultaneously and [Sr +l = 10 mol/L. Therefore, we can write... 

If a patient experiencing digestive problems needs a series of gastrointestinal X rays taken, they frequently must drink what is called a "barium cocktail." It consists of a thick suspension of barium sulfate in water, which is used because barium sulfate is opaque to X rays, and the thick suspension coats the walls of the digestive tract and makes them more visible on the X rays. Barium sulfate may be prepared in the laboratory by mixing a solution of barium chloride with a solution of sodium sulfate, which produces solid barium sulfate suspended in a solution of sodium chloride. Write the unbalanced chemical equation for this process. 

Spectral interferences from the overlap of molecular bands and lines (e g. the calcium hydroxide absorption band on barium at 553.55 nm) cannot be so easily dismissed. Lead seems to be particularly prone to such non-specific absorption problems at the 217.0 nm line (e g. sodium chloride appears to give strong molecular absorption at this wavelength). This type of problem is encountered in practical situations, but can sometimes be removed by the technique of background correction (see Section 2.2.5.2). 

Calcium phosphate has become a common problem with the increase in treatment of municipal waste-water for reuse. Surface waters can also contain phosphate. Calcium phosphate compounds can contain hydroxyl, chloride, fluoride, aluminum, and/ or iron. Several calcium phosphate compounds have low solubility, as shown in Table 7.2. Solubility for calcium carbonate and barium sulfate are also shown by comparison. The potential for scaling RO membranes with the calcium phosphate compounds listed in Table 7.2 is high and will occur when the ion product exceeds the solubility constant. This can occur at orthophosphate concentrations as low as 0.5 ppm. Sodium softening or antisealants together with low pH help to control phosphate-based scaling. 

These substances react, so we have a limiting-quantities problem. We use the net ionic eqnation, and we recognize that the number of millimoles of barium ion and the number of millimoles of chloride ion will not change. 

Violent reaction with benzoyl chloride combined with KOH, Bt2, barium carbonate, CS2, Cr(OCl)2, Cu, Pb, HNO3, BaCOs, H2SO4, hot water, (CH3)2S04, dibromomalononitrile, sulfuric acid. Incompatible with acids, ammonium chloride + trichloroacetonitrile, phosgene, cyanuric chloride, 2,5-dinitro-3-methylbenzoic acid + oleum, trifiuroroacryloyl chloride. Reacts with heavy metals (e.g., brass, copper, lead) to form dangerously explosive heavy metal azides, a particular problem in laboratory equipment and drain traps. When heated to decomposition it emits very toxic fumes of NOx and Na20. See also AZIDES. 

Silver chloride is an example of a soft crystal and is therefore not susceptible to the problems seen when precipitating hard crystals such as barium sulfate and calcium oxalate. This, however, does not mean that the opalescence obtained in a test or standard solution is independent of the operational parameters of the precipitation procedure. But it can be considered a more reproducible and rugged determination compared to hard crystal precipitations, and the steps in the procedure contributing to loss of reproducibility are more easily standardized. The most obvious difference is that a fairly reproducible test procedure can be obtained without the use of a seeded standard, as is the case in 6.3. Calcium and 6.12. Sulfates. 

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