Density, sulfuric acid

Alkenes are good nucleophiles by virtue of their ji electron density. Sulfuric acid is a strong acid, and fully ionised (pK = -9). 

The freezing points of different density sulfuric acid solutions are different even at the same temperature, as shown in Table 5.6 [7]. 

Small amounts of propionitrile and bis(cyanoethyl) ether are formed as by-products. The hydrogen ions are formed from water at the anode and pass to the cathode through a membrane. The catholyte that is continuously recirculated in the cell consists of a mixture of acrylonitrile, water, and a tetraalkylammonium salt the anolyte is recirculated aqueous sulfuric acid. A quantity of catholyte is continuously removed for recovery of adiponitrile and unreacted acrylonitrile the latter is fed back to the catholyte with fresh acrylonitrile. Oxygen that is produced at the anodes is vented and water is added to the circulating anolyte to replace the water that is lost through electrolysis. The operating temperature of the cell is ca 50—60°C. Current densities are 0.25-1.5 A/cm (see Electrochemical processing). 

In Germany and France the Baumii scale is calculated using 144.3 as the constant. The Baumii scale only includes the sulfuric acid concentration range of 0—93.19% H2SO. Higher concentrations are not included in the Baumh scale because density is not a unique function of concentration between 93% and 100% acid. The density of sulfuric acid versus temperature and concentration is shown in Figure 4 (50). 

Fig. 4. Density of sulfuric acid, where the numbers represent the wt % of H2SO4 in H2O (50).

An electrorefining plant may operate with either an acid or an alkaline bath. The acid bath contains stannous sulfate, cresolsulfonic or phenolsulfonic acids (to retard the oxidation of the stannous tin in the solution), and free sulfuric acid with P-naphthol and glue as addition agents to prevent tree-like deposits on the cathode which may short-circuit the cells. The concentration of these addition agents must be carefliUy controlled. The acid electrolyte operates at room temperature with a current density of ca 86—108 A/m, cell voltage of 0.3 V, and an efficiency of 85%. Anodes (95 wt % tin) have a life of 21 d, whereas the cathode sheets have a life of 7 d. Anode slimes may be a problem if the lead content of the anodes is high the anodes are removed at frequent intervals and scmbbed with revolving bmshes to remove the slime (7). 

Titanium Sulfides. The titanium sulfur system has been summarized (4). Titanium subsulftde [1203-08-6] Ti2S, forms as a gray soHd of density 4600 kg/m when titanium monosulftde [12039-07-5], TiS, is heated at 1000°C with titanium ia a sealed tube. It can also be formed by heating a mixture of the two elements at 800—1000°C. The sulfide, although soluble ia concentrated hydrochloric and sulfuric acids, is iasoluble ia alkaUes. 

Titanium trisulfide [12423-80-2], TiS, a black crystalline soHd having a monoclinic stmcture and a theoretical density of 3230 kg/m, can be prepared by reaction between titanium tetrachloride vapor and H2S at 480—540°C. The reaction product is then mixed with sulfur and heated to 600°C ia a sealed tube to remove residual chlorine. Sublimatioa may be used to separate the trisulfide (390°C) from the disulfide (500°C). Titanium trisulfide, iasoluble ia hydrochloric acid but soluble ia both hot and cold sulfuric acid, reacts with concentrated nitric acid to form titanium dioxide. 

Paste Mixing. The active materials for both positive and negative plates are made from the identical base materials. Lead oxide, fibers, water, and a dilute solution of sulfuric acid are combined in an agitated batch mixer or reactor to form a pastelike mixture of lead sulfates, the normal, tribasic, and tetrabasic sulfates, plus PbO, water, and free lead. The positive and negative pastes differ only in additives to the base mixture. Organic expanders, barium sulfate [7727-43-7] BaSO carbon, and occasionally mineral oil are added to the negative paste. Red lead [1314-41 -6] or minium, Pb O, is sometimes added to the positive mix. The paste for both electrodes is characterized by cube weight or density, penetration, and raw plate density. 

Thermal Fixation Properties of Disperse Dyes on Polyester—Gotton. This method assesses the fixation properties of disperse dyes as a function of the time, temperature, dyestuff concentration, or presence and amount of auxiUary agents. The polyester—cotton fabric is padded and dried, the cotton dissolved in sulfuric acid and washed out of the blend, and the amount of dye on the polyester component assessed by either reflectance or measuring the optical density of a solution of dye obtained by extracting the dye with boiling chloroben2ene solvent. 

The primary process variables affecting the economics of sulfuric acid alkylation are the reaction temperature, isobutane recycle rate, reactor space velocity, and spent acid strength. To control fresh acid makeup, spent acid could be monitored by continuously measuring its density, the flow rate, and its temperature. This can reduce the acid usage in alkyla-tion units. 

When 1, 3, 3-triethoxypropene was hydrolyzed with IN sulfuric acid, a solution of malonaldehyde whose optical density was perfectly stable at 350 m/x for at least one week was obtained. If the solution was made alkaline, the optical density at the same wavelength increased by a small value and then remained virtually constant for at least one week (56). It was also observed that in these solutions the extinction coefficient at 350 m/x was very low (observed 8.3, 61.5 and 69, for solutions of pH 0.4, 7.15 and 9.4 respectively) compared with previously reported values which varied from 200 ( 40) to 1000 ( 48). On the other hand, the absorption of solutions having a pH of 3 to 5, increased considerably with time (at pH 4.75, the extinction coefficient of malonaldehyde at 350 m/x was initially about 40 after four weeks a value of about 930 was recorded and the optical density of the solution was still increasing). This increase in absorption was accompanied by a marked decrease in the malonaldehyde content of the solution, as measured by the thiobarbituric acid method. As a corollary, it was found that aqueous solutions of malonaldehyde, prepared by autocatalyzed hydrolysis (33) of the same acetal and which had a pH of about 3.5, showed, at the completion of the hydrolysis, considerably higher extinction coefficient values at 350 m/x than did those malonaldehyde solutions which were prepared by hydrolysis with IN acid and subsequently adjusted to pH 4. It appears, therefore, that at pH values at which most of the periodate oxidations are carried out, malonaldehyde is unstable and undergoes a chemical reaction, the nature of which is not, as yet, known. 

Nitroaniline (13.8 g., 0.10 mole) (Note 2) is dissolved in a hot solution of 75 ml. of 96% sulfuric acid, 100 ml. of phosphoric acid (density 1.7), and 50 ml. of water in a 1-1. beaker. A stirrer and a thermometer are introduced into the mixture, and the beaker is immersed in an ice bath. A solution of 8.3 g. (0.12 mole) of sodium nitrite in 25 ml. of water is added dropwise to the well-stirred solution at such a rate that the temperature is maintained at 10-15°. Excess nitrite is destroyed by adding sulfamic acid in small portions (Note 3). The mixture is cooled to —10° in an ice-salt bath, and about 50 ml. of liquid sulfur dioxide... 

Paste mixing means the addition of sulfuric acid and water. The result is a fairly stiff paste with a density between 1.1 and 1.4gcm 3 containing 8-12wt% of lead sulfate. The water content of thus mix determines the porosity of the active material achievable later (cf. "curing" below). In the paste, a mixture of lead sulfate and basic lead sulfate is formed (cf. Table 1). In the usual mixing process between room temperature and 50 °C, tribasic lead sulfate is formed. The generation of the tetrabasic... 

Satisfactory 40% peracetic acid is obtainable from Buffalo Electrochemical Corp., Food Machinery and Chemical Corp., Buffalo, New York. The specifications given by the manufacturer for its composition are peracetic acid, 40% hydrogen peroxide, 5% acetic acid, 39% sulfuric acid, 1% water, 15%. Its density is 1.15 g. per ml. 

Satisfactory 40% peracetic acid is obtainable from Buffalo Electrochemical Corporation, Food Machinery and Chemical Corporation, Buffalo, New York. The specifications given by the manufacturer for its composition are peracetic acid, 40% hydrogen peroxide, 5% acetic acid, 39% sulfuric acid, 1% water, 15%. Its density is 1.15 g./ml. The peracetic acid concentration should be determined by titration. A method for the analysis of peracid solutions is based on the use of ceric sulfate as a titrant for the hydrogen peroxide present, followed by an iodometric determination of the peracid present.3 The checkers found that peracetic acid of a lower concentration (27.5%) may also be used without a decrease in yield. The product was found to be sufficiently pure, after only one recrystallization from 60 ml. of petroleum ether (b.p. 40-60°) and cooling overnight to —18°, to be used in the next step. 

Aluminum has a low density it is a strong metal and an excellent electrical conductor. Although it is strongly reducing and therefore easily oxidized, aluminum is resistant to corrosion because its surface is passivated in air by a stable oxide film. The thickness of the oxide layer can be increased by making aluminum the anode of an electrolytic cell the result is called anodized aluminum. Dyes may be added to the dilute sulfuric acid electrolyte used in the anodizing process to produce surface layers with different colors. 

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