Curdy precipitate

Experiment 2. When equal volumes of 1.5 M Ba(SCN)2 and 1.5 M MgS04 are mixed, a curdy precipitate immediately forms. Individual particles of BaS04 can be seen as points under magnification at 1500X. 

To 1 1. of boiling water in a 3-I. beaker or large evaporating dish (Note 1) is added 150 g. of mercuric chloride to this mixture is then added, with good stirring, 116 g. of sodium />-toluene-sulfinate (Vol. II, p. 89). A thick, white, curdy precipitate forms at once (Note 2), and in a short time sulfur dioxide is evolved copiously. The heating and stirring are continued until no more sulfur dioxide is evolved, which requires about two hours. 

If a white curdy precipitate, or an opaline tinge or tur- sometimes seen on the lips, chin, or face, will, wheo ... 

Chloride of Silver—Ag Cl—is best obtained by adding a solution of ohloride of sodium in excess to a slightly aoidulated solution of nitrate of silver. The curdy precipitate of chloride of silver requires Very careful washing. 

Lead Vanadite, PbV205 or PbO VOg, is obtained as a brown, curdy precipitate by the action of lead acetate on potassium vanadite.3... 

Manganese dioxide + sulfuric acid Silver nitrate Reddish-brown bromine vapors evolve upon mild heating Pale yellow, curdy, precipitate of silver bromide slightly soluble in ammonia solution insoluble in nitric acid... 

Silver nitrate lodates, 103- White, curdy precipitate of silver iodate soluble in dilute ammonia solution... 

Silver Cobalti-cyanide, Ag3Co(CN)6, is a white curdy precipitate, insoluble in dilute acids, but readily soluble in ammonia. Potassium hydroxide converts it mainly into silver oxide. The ammoniacal solution yields, on concentration, the monammoniate,1... 

B. Add a few drops of Millon s Reagent to a 1 100 aqueous solution. A white, curdy precipitate forms. 

Solutions of chlorides yield with silver nitrate TS a white, curdy precipitate that is insoluble in nitric acid but soluble in a slight excess of 6 A ammonia. 

Silver nitrate solution white, curdy precipitate of silver cyanate, AgOCN, soluble in ammonia solution and in dilute nitric acid. The precipitate appears instantaneously, without complex formation (difference from cyanide) ... 

Silver nitrate solution yellow, curdy precipitate of silver iodide Agl, readily soluble in potassium cyanide and in sodium thiosulphate solutions, very slightly soluble in concentrated ammonia solution, and insoluble in dilute nitric acid. 

Silver nitrate solution white, curdy precipitate of silver citrate, Ag3. C6H507, from neutral solutions. The precipitate is soluble in dilute ammonia solution, and this solution undergoes only very slight reduction to silver on boiling (distinction from tartrate). 

Silver carbonyl ferrocyanide, Ag3[Fe(CN)5CO], is obtained as a white curdy precipitate on addition of the potassium salt to silver nitrate solution in the presence of acetic acid.4 It rapidly darkens even when protected from the light. Insoluble in boiling acetic acid, it is slightly soluble in dilute mineral acids evolving hydrogen cyanide. Potassium hydroxide liberates silver oxide, potassium carbonyl ferrocyanide being simultaneously produced. 

IV. Every acid has properties peculiar to itself. To a solution of silver nitrate add a few drops of nitric acid and then a little of the hydrochloric acid made in A. A white, curdy precipitate, called silver chloride is formed. Expose a little of this precipitate to the sunlight. Determine its solubility by adding separate srnall portions to cold water, hot water, and warm ammonium hydroxide. Tabulate the properties of silver chloride. This whole experiment (IV.), solubility included, constitutes the test for hydrochloric acid. The same test answers for chlorides. Try it. (Compare Exp. 29 p)i)... 

Precipitation reactions with ordinary reagents are not very characteristic. A neutral solution of molybdate gives with silver nitrate a white, curdy precipitate soluble in ammonia or nitric acid, and with barium chloride a white precipitate soluble in hydrochloric acid. Disodium hydrogen phosphate added to a solution of ammonium molybdate gives a yellow precipitate of ammonium 12-molybdophospliate (see p. 164) insoluble in nitric acid, soluble in ammonia. 

According to Gutbier, the addition of a uranyl salt to a solution of potassium tellurate yields a yellow curdy precipitate of uranyl tellurate. 

The presence of carbon dioxide can easily be determined by allowing the gas to pass through a solution of lime water. When carbon dioxide passes through such a solution a white, curdy precipitate is produced which forms in clouds. This precipitate is calcium carbonate. A very simple experiment which will illustrate... 

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