Physical Properties of Hydrogen Peroxide

Hydrogen peroxide and water do not form azeotropic mixtures and can be completely separated by distillation. Most workers, however, obtain 100% mjm hydrogen peroxide by fractional crystallization of highly concentrated solutions. Pure 100% m/m hydrogen peroxide is usually only of academic interest, and is not produced on an industrial scale, although some niche uses may 

Generally, strong acids in hydrogen peroxide remain strong. For example, plots of equivalence conductance versus the half-power of concentration yield straight lines which are characteristic of completely dissociated electrolytes. 

The behaviour of the glass electrode has also been examined.42-43 The glass-calomel electrode system yields stable and reproducible potentials which vary in the normal way with changes in hydrogen ion concentration. However, the EMF of the couple shifts several hundred millivolts as the solution composition changes from water to hydrogen peroxide. Table 1.2 summarizes the apparent and true pH of aqueous solutions of hydrogen peroxide. 

Neutron diffraction studies on the molecular structure of solid hydrogen peroxide have also been made44 and some of the structural data are outlined in Table 1.3. 

Concentration of hydrogen peroxide solution (% m/m) Equivalence pointa True pH Correction factor 

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Table 14,11 Some physical properties of hydrogen peroxide ...

The physical properties of hydrogen peroxide indicate that hydrogen peroxide injection has the potential of combining the more favorable aspects of many enhanced oil-recovery processes, namely ... 

Table 1.1 Physical properties of hydrogen peroxide and water...

Table 2. Physical Properties of Aqueous Hydrogen Peroxide...

Because the reaction takes place in the Hquid, the amount of Hquid held in the contacting vessel is important, as are the Hquid physical properties such as viscosity, density, and surface tension. These properties affect gas bubble size and therefore phase boundary area and diffusion properties for rate considerations. Chemically, the oxidation rate is also dependent on the concentration of the anthrahydroquinone, the actual oxygen concentration in the Hquid, and the system temperature (64). The oxidation reaction is also exothermic, releasing the remaining 45% of the heat of formation from the elements. Temperature can be controUed by the various options described under hydrogenation. Added heat release can result from decomposition of hydrogen peroxide or direct reaction of H2O2 and hydroquinone (HQ) at a catalytic site (eq. 19). 

Barium is a member of the aLkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely aUied series in which the chemical and physical properties of the elements and thek compounds vary systematically with increa sing size, the ionic and electropositive nature being greatest for barium (see Calcium AND CALCIUM ALLOYS Calcium compounds Strontium and STRONTIUM compounds). As size increases, hydration tendencies of the crystalline salts increase solubiUties of sulfates, nitrates, chlorides, etc, decrease (except duorides) solubiUties of haUdes in ethanol decrease thermal stabiUties of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

The accumulation of hydrogen peroxidase affects many intracellular processes and results in hemolysis. These include the cross-linking of membrane proteins hemoglobin denaturation (manifest as Heinz body formation), which in turn affects the physical properties of the erythrocyte and lipid peroxidation, which may affect the cell membrane to cause direct hemolysis (Fig. 11-8). The resultant damage leads to a mixture of intravascular hemolysis and extravascu-lar hemolysis (by which hemolysis occurs in the reticuloendothelial system). In acute hemolytic episodes, the clinical picture is of predominantly intravascular hemolysis, while predominantly extravascular hemolysis is seen in patients with chronic hemolysis. 

Some important physical properties of aqueous solutions of hydrogen peroxide are presented in Tab. 6-3. The toxicological properties and occupational health risks related to H2O2 are briefly summarized below (Ulhnann s, 1989) ... 

Some bases, such as sodium hydroxide and tetramethylammonium hydroxide, are used for sample dissolution, as are some reagents that are not acids or bases, like hydrogen peroxide. The chemical literature contains sample dissolution procedures for virtually every type of material known and should be consulted. For elements and inorganic compounds, the CRC Handbook of Chemistry and Physics gives guidelines for dissolution in the tables of physical properties of inorganic compounds. 

Much controversy has centered around the structure and source of arborine 36, 41). The elucidation of structure (2) (Chart 1) by degradation and synthesis was described in part in a previous chapter in this series 169). Chakravarti et al. 36) proposed the benzylquinazolinone structure (2), whereas Chatterjee and Ghosh Majumdar 42) preferred formula (14) because ozonolysis or periodic acid oxidation of arborine yields benzal-dehyde. The yield of benzaldehyde obtained by these methods, or by oxidation with hydrogen peroxide, is extremely low 34) whereas phenyl-acetic acid may be obtained in almost quantitative yield. The controversy was resolved by Chakravarti et al. 37) on the basis of the physical properties of arborine. Ultraviolet absorption studies and a detailed critical study of the infrared absorption spectra of arborine, dihydroarborine and model compounds of unambiguously defined structure including N-methylanthranilamide, 1,2-dimethylquinazolin-4-one, 2,3-dihydro-l,2-di-methylquinazolin-4-one, 2-ethyl-l-methylquinazolin-4-one, 2,3-dihydro-2-ethyl-l-methylquinazolin-4-one strongly supported structure (2) for arborine. 

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