Sulfuric acid diffusion

Free and total sulfite in wines were determined using the induced oxidation of manganese(ll) and FIA system [1]. Sulfur dioxide as a product of the reaction of the examined sample with sulfuric acid diffused through a PTFE membrane to a solution of Mn(ll) in acetate buffer of pH 5.5. The oxidized Mn formed reacted with iodide to form iodine that was detected at 352 nm. The DL of 1 mg f was reported. 

Second Example Sulfuric Acid Diffusion In the Same Conditions... 

The ESR spectrum of the pyridazine radical anion, generated by the action of sodium or potassium, has been reported, and oxidation of 6-hydroxypyridazin-3(2//)-one with cerium(IV) sulfate in sulfuric acid results in an intense ESR spectrum (79TL2821). The self-diffusion coefficient and activation energy, the half-wave potential (-2.16 eV) magnetic susceptibility and room temperature fluorescence in-solution (Amax = 23 800cm life time 2.6 X 10 s) are reported. 

Silicon used for diffusion treatment of carbon steels enhances corrosion resistance to sulfuric acid. Such a treatment has the surface durability of iron/silicon alloys without their marked brittleness. 

Sometimes the term normal hydrogen electrode (and respectively normal potential instead of standard potential) has been used referring to a hydrogen electrode with a platinized platinum electrode immersed in 1 M sulfuric acid irrespectively of the actual proton activity in this solution. With the latter electrode poorly defined diffusion (liquid junction) potentials will be caused, thus data obtained with this electrode are not included. The term normal hydrogen electrode should not be used either, because it implies a reference to the concentration unit normal which is not to be used anymore, see also below. 

Figure 28, Modification of the Conway technique using rotated bottles in pkwe of the Conway diffusion dish, 1, bottle with a rubber stopper and glass plug containing an edged end which has been dipped in sulfuric acid 2, roughed end of the glass plug 3, rotator with clips holding the bottles in place.

FIG. 25 Typical DPSC data for the oxidation of 10 mM bromide to bromine (forward step upper solid curve) and the collection of electrogenerated Br2 (reverse step lower solid curve) at a 25 pm diameter disk UME in aqueous 0.5 M sulfuric acid, at a distance of 2.8 pm from the interface with DCE. The period of the initial (generation) potential step was 10 ms. The upper dashed line is the theoretical response for the forward step at the defined tip-interface separation, with a diffusion coefficient for Br of 1.8 x 10 cm s . The remaining dashed lines are the reverse transients for irreversible transfer of Br2 (diffusion coefficient 9.4 x 10 cm s ) with various interfacial first-order rate constants, k, marked on the plot. (Reprinted from Ref. 34. Copyright 1997 American Chemical Society.)... 

M sulfuric acid to air [34]. As discussed above, for the aqueous-DCE interface, the rate of this irreversible transfer process (with the air phase acting as a sink) was limited only by diffusion of Bt2 in the aqueous phase. A lower limit for the interfacial transfer rate constant of 0.5 cm s was found [34]. 

A bottle of the complex exploded in storage. No cause was established, but diffusive ingress of moisture to form sulfuric acid, and subsequent hydrolysis of the solvent with formation of carbon monoxide appear to be possible contributory factors. 

In a fixed-bed catalytic reactor for a fluid-solid reaction, the solid catalyst is present as a bed of relatively small individual particles, randomly oriented and fixed in position. The fluid moves by convective flow through the spaces between the particles. There may also be diffusive flow or transport within the particles, as described in Chapter 8. The relevant kinetics of such reactions are treated in Section 8.5. The fluid may be either a gas or liquid, but we concentrate primarily on catalyzed gas-phase reactions, more common in this situation. We also focus on steady-state operation, thus ignoring any implications of catalyst deactivation with time (Section 8.6). The importance of fixed-bed catalytic reactors can be appreciated from their use in the manufacture of such large-tonnage products as sulfuric acid, ammonia, and methanol (see Figures 1.4,11.5, and 11.6, respectively). 

Long chain alkylmercaptans and disulfides readily self-assemble on gold surfaces to form compact organized monolayers in which the sulfur is chemisorbed to the gold and the hydrocarbon tail is extended away from the surface (1.-5). The mercaptan monolayers strongly inhibit gold oxidation in dilute sulfuric acid and also block diffusion of aqueous ions (e.g. Fe 2 3, Fe(CN) 63, ... 

Colorless gas characteristic odor of rotten eggs odor threshold Ippm sweetish taste fumes in air flammable gas, bums with a pale blue flame refractive index at 589.3nm, 1.000644 at 0°C and 1 atm density 1.539 g/L at 0°C critical temperature 100.4°C critical pressure 88.9 atm liquefies at -60.7°C solidifies at -85.5°C velocity of sound 289 m/sec in H2S gas slightly soluble in water (0.4% at 20° C) pH of a saturated aqueous solution 4.5 slightly acidic diffusivity in water at 16°C, 1.77x10 cm /sec soluble in carbon disulfide, methanol, acetone very soluble in N-methylpyrrolidinone and alka-nolamines (salt formation occurs salt dissociates on heating) liquid H2S dissolves sulfur and SO2. 

Hanson, D. R and A. R. Ravishankara, Uptake of HCI and HOCI onto Sulfuric Acid Solubilities, Diffusivities, and Reaction, J. Phys. Chem., 97, 12309-12319 (1993b). 

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