Sulphur dioxide, determination

Determination of resistance to humid atmospheres containing sulphur dioxide Determination of resistance to humidity (continuous condensation)... 

Sulphur dioxide (free and total) Wines Pervaporation UV—Vis 1.2 gg mL 1 (both analytes) Flow injection system p-rosaniline plus formaldehyde solution as the acceptor stream sample alkalinisation prior to injection for total sulphur dioxide determination [551]... 

Quality control procedures that are unique for dried fruit products include moisture content determination, sulphur dioxide determination (pre- and post-drying), physical characteristics of dried fruit and drying ratio (Woodroof and Luh 1975). 

Sulphur dioxide Directional dust gauges Sampling equipment for determination of gaseous sulphur Thorin spectrophotometry... 

Various methods can be used to determine the concentration of sulphur dioxide in the vicinity of steel test specimens. They all provide suitable information on the relationship between sulphur dioxide and corrosion. However, the actual amount of sulphur dioxide in contact with the steel surface is more important than the concentration, as shown in the work reported by Walton et al. ... 

Industrial atmospheres usually accelerate the corrosion of zinc. When heavy mists and dews occur in these areas, they are contaminated with considerable amounts of acid substances such as sulphur dioxide, and the film of moisture covering the metal can be quite acid and can have a pH as low as 3. Under these conditions the zinc is dissolved but, as the corrosion proceeds, the pH rises, and when it has reached a sufficiently high level basic salts are once more formed and provide further protection for the metal. These are usually the basic carbonate but may sometimes be a basic sulphate. As soon as the pH of the moisture film falls again, owing to the solution of acid gases, the protective film dissolves and renewed attack on the metal occurs. Hudson and Stanners conducted tests at various locations in order to determine the effect of atmospheric pollution on the rate of corrosion of steel and zinc. Their figures for zinc are given in Table 4.34 and clearly show the effect which industrial contamination has on the corrosion rate. 

Rubber vulcanised-determination of adhesion to, and corrosion of, metals Corrosion of metals and alloys determination of dezincification resistance of brass Sulphur dioxide test with general condensation of moisture... 

Nickel-based alloys-Determination of resis-ance to intergranular corrosion Corrosion tests in artificial amospheres at very low concentrations of polluting gas(es) Test /. .-sulphur dioxide test for contacts and connectors... 

Organic sulphur is converted to sulphur trioxide and sulphur dioxide by the combustion, absorbed in hydrogen peroxide, and the sulphur determined as sulphate. 

Discussion. This gravimetric determination depends upon the separation and weighing as elementary selenium or tellurium (or as tellurium dioxide). Alkali selenites and selenious acid are reduced in hydrochloric acid solution with sulphur dioxide, hydroxylammonium chloride, hydrazinium sulphate or hydrazine hydrate. Alkali selenates and selenic acid are not reduced by sulphur dioxide alone, but are readily reduced by a saturated solution of sulphur dioxide in concentrated hydrochloric acid. In working with selenium it must be remembered that appreciable amounts of the element may be lost on warming strong hydrochloric acid solutions of its compounds if dilute acid solutions (concentration <6M) are heated at temperatures below 100 °C the loss is negligible. 

B. Determination of tellurium Procedure. The solution should contain not more than 0.2 g tellurium in 50 mL of 3M hydrochloric acid (ca 25 per cent by volume of hydrochloric acid). Heat to boiling, add 15 mL of a freshly prepared, saturated solution of sulphur dioxide, then 10 mL of a 15 per cent aqueous solution of hydrazinium chloride, and finally 25 mL more of the saturated solution of sulphur dioxide. Boil until the precipitate settles in an easily filterable form this should require not more than 5 minutes. Allow to settle, filter through a weighed filtering crucible (sintered-glass, or porcelain), and immediately wash with hot water until free from chloride. Finally wash with ethanol (to remove all water and prevent oxidation), and dry to constant weight at 105 °C. Weigh as Te. 

C. Determination of mixtures of selenium and tellurium Procedure. Dissolve the mixed oxides (not exceeding 0.25 g of each) in 100 mL of concentrated hydrochloric acid, and add with constant stirring 50 mL cool concentrated hydrochloric acid which has been saturated with sulphur dioxide at the ordinary temperature. Allow the solution to stand until the red selenium has settled, filter through a weighed filtering crucible (sintered-glass or porcelain) and complete... 

Determination of thallium as chromate Discussion. The thallium must be present in the thallium(I) state. If present as a thallium(III) salt, reduction must be effected (before precipitation) with sulphur dioxide the excess of sulphur dioxide is boiled off. 

Determination of chlorate as silver chloride Discussion. The chlorate is reduced to chloride, and the latter is determined as silver chloride, AgCl. The reduction may be performed with iron(II) sulphate solution, sulphur dioxide, or by zinc powder and acetic (ethanoic) acid. Alkali chlorates may be quantitatively converted into chlorides by three evaporations with concentrated hydrochloric acid, or by evaporation with three times the weight of ammonium chloride. 

Note. Hypochlorites and chlorites may be reduced to chlorides with sulphur dioxide, and determined in the same way. 

Determination as copper (I) thiocyanate, CuSCN. The solution (100 mL) should be neutral or slightly acid (hydrochloric or sulphuric acid), and contain not more than 0.1 g SCN . It is saturated with sulphur dioxide in the cold (or 50 mL of freshly prepared saturated sulphurous acid solution added), and then treated dropwise and with constant stirring with about 60 mL of 0.1M copper sulphate solution. The mixture is again saturated with sulphur dioxide (or 10 mL of... 

For the determination of small amounts of water, Karl Fischer (1935) proposed a reagent prepared by the action of sulphur dioxide upon a solution of iodine in a mixture of anhydrous pyridine and anhydrous methanol. Water reacts with this reagent in a two-stage process in which one molecule of iodine disappears for each molecule of water present ... 

Pt 7 - Determination of mass concentration of sulphur dioxide in ambient air. Thorin spectrophotometric method. 

A plethora of chemical compounds for the determination of small amounts of water present in organic solids, pharmaceutical substances and organic solvents have been devised over a length of time. But unquestionably the most important of these is the one proposed by Karl Fischer (1935), which is considered to be relatively specific for water. It essentially makes use of the Karl Fischer reagent which is composed of iodine, sulphur dioxide, pyridine and methanol. 

Determination Test, Weight loss test, Eschke test, Salt spray test and Sulphur dioxide test at 50°C. Mechanism of inhibition of corrosion and surface study of mild steel was also studied by Metallurgical Resesarch Microscopy and Scanning electron Microscopy. 

To obtain a sample solution, gaseous samples are usually passed at a controlled flow-rate through a suitable absorption solution. For example, when determining the concentration of sulphur dioxide in the atmosphere, the air is passed through a tetrachloromercurate solution and sulphur dioxide is trapped as a result of the reaction... 

A rehable flash distillation unit as described above has many apphcations for AAI methodology, and it can also he used coupled to AAII technology. For the determination of sulphur dioxide in wine and soft drinks it has many advantages over the commercial methods based on a gas membrane. 

Olah has determined the pnmr and cnmr spectra of a number of protonated carbonyl compounds in fluorosulphuric acid-antimony pentafluoride-sulphur dioxide solution (Olah and White, 1968 Olah et al. 1972). The carbon-13 data are given in Tables 9 and 10. The proton data are not included in Table 9, since the anisotropy of the oxygen function obscures any interpretation. A correlation of some... 

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