Perchlorate ions chlorate

Taking francium as an example, it was assumed that the minute traces of francium ion Fr could be separated from other ions in solution by co-precipitation with insoluble caesium chlorate (VII) (perchlorate) because francium lies next to caesium in Group lA. This assumption proved to be correct and francium was separated by this method. Similarly, separation of astatine as the astatide ion At was achieved by co-precipitation on silver iodide because silver astatide AgAt was also expected to be insoluble. 

Unexpectedly we find that the bromate(V) ion in acid solution (i.e. effectively bromic(V) acid) is a more powerful oxidising agent than the chlorate(V) ion, CIO3. The halates(V) are thermally unstable and can evolve oxygen as one of the decomposition products. Potassium chlorate(V), when heated, first melts, then resolidifies due to the formation of potassium chlorate(VII) (perchlorate) ... 

The standard potential for the anodic reaction is 1.19 V, close to that of 1.228 V for water oxidation. In order to minimize the oxygen production from water oxidation, the cell is operated at a high potential that requires either platinum-coated or lead dioxide anodes. Various mechanisms have been proposed for the formation of perchlorates at the anode, including the discharge of chlorate ion to chlorate radical (87—89), the formation of active oxygen and subsequent formation of perchlorate (90), and the mass-transfer-controUed reaction of chlorate with adsorbed oxygen at the anode (91—93). Sodium dichromate is added to the electrolyte ia platinum anode cells to inhibit the reduction of perchlorates at the cathode. Sodium fluoride is used in the lead dioxide anode cells to improve current efficiency. 

Perchlorates are also produced electrochemicaUy. The oxidation of chlorate to perchlorate ions occurs at a higher positive potential (above 2.0 V vs. SHE) than chloride ion oxidation. The current yield of perchlorate is lower when chloride ions are present in the solution hence, in perchlorate production concentrated pure chlorate solutions free of chlorides are used. Materials stable in this potential range are used as the anodes primarily, these include smooth platinum, platinum on titanium, and lead dioxide. 

When chlor-alkali electrolysis is conducted in an undivided cell with mild-steel cathode, the chlorine generated anodically will react with the alkali produced cathodically, and a solution of sodium hypochlorite NaClO is formed. Hypochlorite ions are readily oxidized at the anode to chlorate ions this is the basis for electrolytic chlorate production. Perchlorates can also be obtained electrochemically. 

In choice A, KC103 is potassium chlorate, not perchlorate. In choice B, CuO is copper (II) oxide, to distinguish it from copper (I) oxide, Cu20. In choice C, the formula for aluminum sulfate is A12(S04)3. In D, the formula for magnesium phosphate is Mg3(P04)2. If you missed these, review inorganic nomenclature and refer to pages 94 and 95 of this book to become familiar with common ions and their charges. 

In a similar way, hypochlorous acid yields the hypochlorite ion, chlorous acid yields the chlorite ion, chloric acid yields the chlorate ion, and perchloric acid yields the perchlorate ion (Table 2.4). 

Chlorate concentration increases during electrolysis, but exerts no influence upon the process, as its decomposition voltage is much higher than that of chloride. Chlorate ions are oxidized into perchlorate ions not sooner than tho chloride concentration in the electrolyte drops below 5 % of the initial value. Therefore, chlorate can accumulate in the solution up to the saturation. 

Very few binary compounds of this class have been described, but CIO is widely used as a counter ion for the preparation of many of the cationic species of the other neutral ligands, despite the instability that gives some risk of explosion For many years, it was regarded as the standard for non-coordination —especially in aqueous solution—and both the chlorate and perchlorate crystallized from aqueous solution as [Mn(H20)6]X2. However, the anhydrous Mn(C104)2 can be... 

Ans. (a) Per- means more oxygen atoms. For example, the perchlorate ion (C104 ) has more oxygen atoms than does the chlorate ion (C103 ). (b) Hypo- means fewer oxygen atoms. For example, the hypochlorite... 

Write electrode equations for the electrolytic production of (a) ferric ion from ferrous ion (b) magnesium metal frtmi molten magnesium chloride (c) perchlorate ion, CIO4—, from chlorate ion, CIOg, in aqueous solution ... 

F. Winteler has studied the conditions favourable for the production of perchlorates, and found that if the concentration of the chloride exceeds 10 per cent., very little perchlorate will be formed in warm soln. The anode temp, should be kept low by artificial cooling, since the yield falls when the temp, is raised and it is preferable to have a high concentration of chlorate. In the electrolysis of alkali chloride soln., no perchlorate is formed until nearly all the chloride has been converted to chlorate. The yield is reduced in alkaline soln. probably owing to the smaller number of chlorate ions and the increasing number of hydroxyl ions liberated as the alkalinity is increased—hydroxyl ions are more easily discharged than chlorate ions. Increasing the current density counteracts the effect of increasing alkalinity. 

Hydrogen fluoride was identifled by vacuum distillation, formation of NaF.HF, and titration. Hydrogen chloride was identifled through formation of silver chloride. Ammonia was determined quantitatively by Kjeldahl s method. The oxynitrogen acids or oxychlorine acids were identified qualitatively by Lunge s reagent. Anions of the oxychlorine acids—i.e., chlorite, chlorate, or perchlorate— were identified by reduction with zinc to chloride ion. 

This procedure has been applied to the determination of organic peroxides hydroxyl amine chromium(VI) cerium(IV) molybdenum(VI) nitrate, chlorate, and perchlorate ions and numerous other oxidants (see, for example. Problems 20-37 and 20-39). 

At pH 7, [H ] = 10" M and assuming that both perchlorate and chlorate ions are present at unit activity, the reduction potential is... 

In the case of the chlorate ion, C103 , the oxyion with one more oxygen, C104", adds a per- prefix to chlorate, becoming perchlorate ion. The oxyion with one less oxygen than the chlorite, C102 , is the hypochlorite ion, CIO". Chlorine is one of the few elements that can form four different oxyions. 

---