Oxo-Acids of Halogens and their Salts.pptx

Acids are a class of chemical substances that, when dissolved in water, typically produce hydrogen ions (H⁺). Oxo acids, also known as oxy acids, are a type of acid that contain oxygen atoms, along with hydrogen and another element (often a nonmetal). The general structure of an oxo acid is HnXOm, where "X" where represents the halogen atom and n represents the number of oxygen atoms bonded to the halogen, "n" is the number of hydrogen atoms, and "m" is the number of oxygen atoms. The strength of an oxo acid depends on factors such as the number of oxygen atoms and the electronegativity of the central atom.
oxo acids are versatile compounds with widespread applications in various fields, ranging from industry and agriculture to biology and medicine. Understanding their properties and reactions is crucial for advancing scientific knowledge and technology.

1.   OXO-ACIDS OF HALOGENS &   THEIR SALTS MOHAMMED FARHAN V Dep. of Chemistry, PONDICHERRY UNIVERSITY CHEM-211

2. OXO-ACIDS OF HALOGENS 2  Hypohalous Acids  HOX   Halous Acids  HXO 2  Halic Acids    HXO 3   Perhalic Acids    HXO 4 All these structures are based on a tetrahedron. The sp3 hybrid orbitals used for bonding form only weak σ bonds, because the s and p levels differ appreciably in energy. The ions are stabilized by strong pπ – dπ bonding between full 2p orbitals on oxygen with empty d orbitals on the halogen atoms

3. 3 Hypofluorous Acid Why HOF is unstable?         Fluorine has very small size, high electronegativity and no   d  orbitals thus cannot form   p π- d π bonds. For a long time it was thought that F could not form any oxoacids, it is now known that HOF can be made under special conditions. Therefore it forms only one oxoacid HOF   is a colorless unstable gas  It is a strong oxidizing agent and oxidizes H 2 O to H 2 O 2  quite readily HOF is explosive at room temperature, forming HF and O 2   2 HOF  →   2 HF + O 2 -40 °C F 2 + H 2 O                HOF + HF It was isolated in the pure form by passing F 2   gas over ice at −40 °C Oxo-acids of Fluorine  

4. Hypochlorous Acid 4 Chlorous Acid They are week acid, but they are good oxidizing agents especially in acidic solutions In Organic chemistry,  HOCl coverts Alkenes to Chlorohydrins Sodium hypochlorite ( NaClO ) and Calcium hypochlorite ( Ca( ClO ) 2 ) are ingredients in many commercial bleaches, deodorants, disinfectants and sterilizing agent  HClO 2   is made by treating berium  chlorite with sulfuric acid, and filtering off the BaSO 4 They can be prepared by shaking the halogen with freshly precipitated   HgO   in water                 2 HgO + H2O + 2 Cl2 →   HgO  ∙ HgCl2 + 2 HOCl Ba(ClO 2 ) 2 + H 2 SO 4   →   2 HClO 2 + BaSO 4 HClO 2 is a powerful oxidizing agent, although its tendency to disproportionation counteracts its oxidizing potential. It is a weak acid, but stronger than HOCl Salts of HClO 2 are called chlorites, and are made either from ClO 2 and sodium hydroxide, or  ClO 2 and sodium peroxide 2 ClO 2  + 2 NaOH     →     NaClO 2 + NaClO 3 + H 2 O                                 2 ClO 2 + Na 2 O 2 → 2 NaClO 2 + O 2                                          Chlorite    Chlorate Chlorites are used as bleaches Oxo-acids of Chlorine  

5. Chloric   Acid 5 It can be prepared by the reaction of sulfuric acid with barium chlorate, the insoluble barium sulfate being removed by precipitation Chlorates are much more soluble than bromates and iodates Solid chlo rates, bromates and iodates should be handled with care Ba ( ClO 3 ) 2  + H 2 SO 4   → 2 HClO 3  + BaSO 4 Another method is the heating of hypochlorous acid, producing chloric acid and HCl 3 HClO → HClO 3  + 2 HCl Chlorates may be made in two ways Passing Cl2 into a hot solution of NaOH Electrolysing  hot chloride solutions that are vigorously stirred Chloric acid is a powerful oxidizing agent. Most organics and flammables will deflagrate on contact 6 NaOH + 3 Cl 2           NaClO 3 + 5 NaCl + 3 H 2 O   2 C l - + 2 H 2 O                 Cl 2 + H 2 + 2 OH -   6 NaOH + 3 Cl 2           NaClO 3 + 5 NaCl + 3 H 2 O 80  °C electrolyze Uses, Chlorates  are used to make fireworks and matches. Sodium chlorate is widely used as a powerful weedkiller. Solid sodium chlorate has been used by terrorists in making bombs

6. Perchloric  Acid 6 Treating sodium perchlorate solution with hydrochloric acid (HCl) produces perchloric acid by precipitating solid sodium chloride. It can also be prepared in laboratories by treating barium perchlorate (Ba(ClO 4 ) 2 ) with sulphuric acid (H 2 SO 4 ) which precipitates barium sulphate (BaSO 4 ) and leaves perchloric acid NaClO 4  + HCl → NaCl + HClO 4 Ba(ClO 4 ) 2  + H 2 SO 4  →  2 HClO 4  + BaSO 4 Uses , NH 4 ClO 4 is a white solid and was formerly used as a blasting compound in mining. It is now used in the booster rockets in the Challenger Space Shuttle to oxidize the fuel (Al powder). NH 4 ClO 4 will absorb sufficient ammonia to liquefy itself. KClO 4 is used in fireworks and flares. MgClO4 is used as the electrolyte in so-called ‘dry batteries’. It is very hygroscopic, and is a very effective desiccant called ‘ anhydrone ’. HClO 4   is a colorless compound and stronger acid than  sulfuric acid, nitric acid and hydrochloric acid It is a powerful oxidizer

7. Oxo-acids of Bromine 7 Bromic Acid   Perbromic Acid It is weak and unstable acid, They also called " Bromanol " or " H ydroxidobromine " HOBr is used as a bleach, an oxidizer, a deodorant, and a disinfectant, due to its ability to kill the cells of many pathogens. hypobromite salts are unstable and undergo a slow disproportionation reaction to yield the respective bromate and bromide salts. Its chemical and physical properties are similar to those of other hypohalites It is only exist in aqueous solution, It is a colorless solution that turns yellow at room temperature as it decomposes to bromine Bromic acid and bromates are powerful oxidizing agents Ba(BrO 3 ) 2  + H 2 SO 4  → 2 HBrO 3  + BaSO 4 Perbromic acid is unstable and cannot be formed by displacement of chlorine from perchloric acid, as periodic acid is prepared; it can only be made by protonation of the  perbromate  ion. It decomposes rapidly on standing to bromic acid and oxygen. It reacts with bases to form perbromate salts. Hypobromous  Acid

8. Oxo-acids of Iodine 8 Hypoiodous  acid is a greenish yellow solution with chemical formula HOI. Iodine reacts with cold and dilute sodium hydroxide solution sodium hypoiodite is formed which undergoes hydrolysis to give hypoiodous acid HIO 3 is soluble in water and also exists in a pure state. Iodic acid can be obtained by oxidizing iodine with strong oxidizers like nitric acid, hydrogen peroxide, chloric acid and chlorine. Hypoiodous Acid Iodic Acid Uses , Used as a strong oxidizing agent Used in rocket fuels and as an insulator Used to eliminate chloramines from swimming pool water to avoid the build-up of eye irritants 2 NaOH + I 2   → NaIO + NaI + H 2 O                                                Another ;     NaOH + I 2   → HOI + NaI NaIO + H 2 O → NaOH + HOI Uses , It is used in the salt industry to synthesize sodium and potassium iodate to increase the iodine content in the salt In analytical chemistry, it is used as a strong acid It may be used to standardize solutions of both weak and strong bases, using methyl red or methyl orange as the indicator.

9. Hydration of HIO 4  gives H 5 IO 6  and dehydration of H 5 IO 6  gives HIO 4 . 9  Periodic acid     It can exist in two forms orthoperiodic acid ( H 5 IO 6 ) metaperiodic acid ( HIO 4 ) Orthoperiodic acid Metaperiodic  acid Periodic acid is a strong oxidizing agent, commonly used to oxidize glycols. HIO 4  is the highest oxoacid of iodine Periodic acid was discovered by eminent scientists Heinrich Gustav Magnus and C. F.  Ammermüller  in the year 1833 Conjugate base is Periodate. It is used to separate ammonia (NH 3 ) from hydroxy amino acids and produce acetaldehyde and higher aldehydes.

10. STRENGHT OF THE OXO-ACID 10 HClO 4 is an extremely strong acid, whilst HOCl is a very weak acid Note that the acidic nature of oxoacids is due to the highly polar nature of the bond between hydrogen and oxygen HClO 4  >HBrO 4   >HIO 4 As the electronegativity of halogen decreases from F to I the polarity of the H—O bond also decreases as oxygen can attract electron density from both H and halogen resulting the decrease in ionization.   Therefore higher the electronegativity of the halogen atom is higher acid strength. Acidic strengh of Perhalic acids Acidic strenght of Oxo-acids of Halogen with same oxidation number decreases as we move down the group Acidic strenght of Hypohalous Acids                                                      HOF   > HOCl   > HOBr   > HOI But in the case of halic acids of different halogens the acidic character should increase in the order;

11. Thermal Stability 11 Thermal stability of both oxo-acid and their aions depend upon the Oxidation state, when   the oxidation state increases with increasing thermal stability HClO   <  HClO 2   <  HClO 3   <  HClO 4   Cl—O – > ClO 2 − > ClO 3 − > ClO 4 −   Oxidizing Power As the stability of the anion increased from ClO – to ClO 4 − the oxidizing power would decrease from ClO – to ClO 4 − .When the Oxidation state increases with decreases the Oxidation power.

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