Halic acid

Many salt-like halides can be prepared by the action of the hydro-halic acid. HX, on the metal or its oxide, hydroxide or carbonate. The halides prepared by this method are often hydrated, particularly when a less electropositive metal is involved, for example zinc, iron. 

Halic acids HOClOi H0Br02 HOIO2 Halates... 

The halic acids may not be industrially important, but their salts certainly are. Sodium chlorate is produced in enormous quantities and used in processes in which its oxidizing strength makes it a versatile bleach. One such use is in making paper, and potassium chlorate is used as the oxidizing agent in matches. The decomposition of potassium chlorate was discussed in Chapter 13 in connection with the laboratory preparation of oxygen. 

The halic acids are strong, as would be expected on the basis of the formula (HO)aXOf, with b = 2, but they are not stable as pure compounds. The anions are isoelectronic with S() /, and they have the C3t, structure... 

Related work has been reported in amide solvents with halide or hydro-halic acid promoters (196). Ethanol and acetaldehyde as well as methanol are observed. Enhanced yields of acetaldehyde appear to be obtainable by operating such a system at reduced temperatures, although overall rates of CO reduction suffer. 

Hence, the concentrations of free halogen, halic acid, and hypohalite vary greatly with the acidity. For example, at pH 1, the total chlorine present... 

The compounds I(OH)6(ONa), OI(OH)3,02I(0Ag)3, and OjI(OAg) are known, corresponding to the theoretical perhalic acids. Those corresponding to the halic acids are 02Br(0H) bromic acid, and I(OH) and 02I(0H), iodic acids. Br(ONa) and I(ONa), named respectively hypo-bromite and hypoiodite of sodium, are also known. 

Other procedures for the simultaneous determination of chlorides, bromides and iodides were suggested by Russel [576], He analysed 2-haloethanols produced by the reaction of ethylene oxide with HC1, HBr and HI. A sample of halides was converted into halic acids with the aid of a strongly acidic ion exchanger. Ethylene oxide was allowed to pass through 10 ml of the acids cooled to 4°C for 15 min. In another procedure, 1 ml of liquid ethylene oxide was added to the acids. After 1 h, the sample was diluted to 15 ml and 1 fi was analysed using 12% of EGS at 100°C. The method was illustrated on the... 

The pnre halic acids are prodnced by adding sulfuric acid to an aqneons solntion of the appropriate barium salt and precipitating insolnble barium sulfate (equation 118). 

All the halogens form halic acids in aqueous solution, which can be concentrated to about 40-50% when evaporated by heating carefully under reduced pressure. At higher concentrations, these disproportionate into perchloric acid, whereas the bromate decomposes to bromine and oxygen. Both chloric and bromic are strong acids in aqneons solntion (p/fa < 0), whereas iodic acid is slightly weaker (p/fa = 0.804). 

In practical terms, hydrochloric acid is the most important of the hydro-halic acids, the aqueous solutions of the hydrogen halides. About 3 million tons of hydrochloric acid are produced annually for use in cleaning steel before galvanizing and in the manufacture of many other chemicals. 

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