Insoluble substance forms and separates from

Precipitation A process in which an insoluble substance forms and separates from a solution. 

Potential energy energy due to position or composition. (6.1) Precipitation reaction a reaction in which an insoluble substance forms and separates from the solution. (4.5)... 

When two solutions are mixed, an insoluble substance sometimes forms that is, a solid forms and separates from the solution. Such a reaction is called a precipitation reaction and the solid that forms is called a precipitate. For example, a precipitation reaction occurs when an aqueous solution of potassium chromate, K2Cr04(aq), which is yellow, is mixed with a colorless aqueous solution containing barium nitrate, Ba(N03)2(aq). As shown in Fig. 4.12, when these solutions are mixed, a yellow solid forms. What is the equation that describes this chemical change To write the equation we must know the identities of the reactants and products. The reactants have already been described K2Cr04(aq) and Ba(N03)2(tf<7). Is there some way we can predict the identities of the products In particular, what is the yellow solid ... 

When two solutions are mixed, an insoluble substance sometimes forms that is, a solid forms and separates from the solution. Such a reaction is called a precipitation reaction, and the solid that forms is called a precipitate. For example, a precipitation reaction occurs when an aqueous solution of potassium chromate, K2Cr04(a ), which is yellow, is added to a colorless aqueous solution containing barium nitrate. 

Table 1 indicates the solids or substances that can be effectively separated by the adsorptive bubble separation process. In general, the light-weight suspended solids, such as fibers, activated sludge, free oil, chemical floes, and fats, can be readily separated by the process in accordance with the physical-chemical bubble attachment mechanism shown in Fig. 1. The colloidal solids, soluble organics, soluble inorganics, and surface-active substances can be separated from the bulk liquid by the bubble separation process after they are converted from colloidal or soluble form into insoluble form (i.e., suspended solids), which can then be floated by gas bubbles. 

In a 500 ml. flask, fitted with a reflux condenser, place 53 g. of 1-chloro-methylnaphthalene (Section IV.23), 84 g, of hexamethylenetetramine and 250 ml. of 1 1 acetic acid [CAUTION 1-Chloromethylnaphtha-lene and, to a lesser degree, a-naphthaldehyde have lachrymatory and vesicant properties adequate precautions should therefore be taken to avoid contact with these substances.] Heat the mixture under reflux for 2 hours it becomes homogeneous after about 15 minutes and then an oil commences to separate. Add 100 ml. of concentrated hydrochloric acid and reflux for a further 15 minutes this will hydrolyse any SchifiF s bases which may be formed from amine and aldehyde present and will also convert any amines into the ether-insoluble hydrochlorides. Cool, and extract the mixture with 150 ml. of ether. Wash the ether layer with three 50 ml. portions of water, then cautiously with 50 ml. of 10 per cent, sodium carbonate solution, followed by 50 ml. of water. Dry the ethereal solution with anhydrous magnesium sulphate, remove the ether by distillation on a steam bath, and distil the residue under reduced pressure. Collect the a-naphthaldehyde at 160-162718 mm. the yield is 38 g. 

When a substance made up of ions is dissolved in water, the dissolved ions behave independently. That is, they undergo their own characteristic reactions regardless of what other ions may be present. For example, barium ions in solution, Ba2, always react with sulfate ions in solution, S04 , to form an insoluble ionic compound, BaS04(s), no matter what other ions are present in the barium solution. If a solution of barium chloride, BaCK, and a solution of sodium sulfate, Na S04, arc mixed, a white solid, barium sulfate, is produced. The solid can be separated from the solution by filtration, and the resulting solution contains sodium chloride, just as it would if solid NaCl were added to water. In other words, when the two solutions are mixed, the following reaction occurs ... 

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