Sulfur dioxide, hydrogen peroxide determination

Sulfur dioxide, hydrogen peroxide determination, 637 Sulfur peroxides, 1002-39 Sunflower oil... 

The temperature and density structure of the troposphere, along with the concentrations of major constituents, are well documented and altitude profiles have been measured over a wide range of seasons and latitudes for the minor species water, carbon dioxide, and ozone. A few profiles are available for carbon monoxide, nitrous oxide, methane, and molecular hydrogen, while only surface or low-altitude measurements have been made for nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, hydrogen sulfide, and nonmethane hydrocarbons. No direct measurements of nitric acid and formaldehyde are available, though indirect information does exist. The concentrations of a number of other important species, such as peroxides and oxy and peroxy radicals, have never been determined. Therefore, while considerable information concerning trace constituent concentrations is available, the picture is far from complete. 

Analytical Methods. The official NIOSH recommended method for determining sulfur dioxide in air consists of drawing a known prefiltered volume of air through a bubbler containing hydrogen peroxide, thus oxidising the sulfur dioxide to sulfuric acid. Isopropyl alcohol is then added to the contents in the bubbler and the pH of the sample is adjusted with dilute perchloric acid. The resultant solution is then titrated for sulfate with 0.005 M. barium perchlorate, and Thorin is used as the indicator. 

Sulfur Dioxide EPA Method 6 is the reference method for determining emissions of sulfur dioxide (SO9) from stationary sources. As the gas goes through the sampling apparatus (see Fig. 25-33), the sulfuric acid mist and sulfur trioxide are removed, the SO9 is removed by a chemical reaction with a hydrogen peroxide solution, and, finally, the sample gas volume is measured. Upon completion of the rim, the sulfuric acid mist and sulfur trioxide are discarded, and the collected material containing the SO9 is recovered for analysis at the laboratory. The concentration of SO9 in the sample is determined by a titration method. 

When lcad(II) sulfide is treated with hydrogen peroxide, the possible products are either lead(II) sulfate or lead(IV) oxide and sulfur dioxide, (a) Write balanced equations for the two reactions, (b) Using data available in Appendix 2A, determine which possibility is more likely. 

This is one source of acid rain, a serious environmental problem. The sulfur dioxide content of an air sample can be determined. A sample of air is bubbled through an aqueous solution of hydrogen peroxide to convert all of the SO2 to H2 SO4. H2 O2 + SO2 H2 SO4 Titration of the resulting solution completes the analysis (both H atoms of H2 SO4 are titrated). In one such case, the analysis of 1.55 X 10 Lof Los Angeles air gave a solution that required 5.70 mL of 5.96 X 10 M NaOH to complete the titration. Determine the number of grams of SO2 present in the air sample. 

Dasgupta, P. K., S. Dong, H. Hwang, H.-C. Yang, and Z. Genfa, Continuous Liquid-Phase Fluorometry Coupled to a Diffusion Scrubber for the Real-Time Determination of Atmospheric Formaldehyde, Hydrogen Peroxide, and Sulfur Dioxide, Atmos. Environ., 22, 949-964 (1988). 

The Reich test is used to estimate sulfur dioxide content of a gas by measuring the volume of gas required to decolorize a standard iodine solution (274). Equipment has been developed commercially for continuous monitoring of stack gas by measuring the near-ultraviolet absorption bands of sulfur dioxide (275—277). The determination of sulfur dioxide in food is conducted by distilling the sulfur dioxide from the acidulated sample into a solution of hydrogen peroxide, followed by acidimetric titration of the sulfuric acid thus produced (278). Analytical methods for sulfur dioxide have been reviewed (279). 

Sulfur in organic and biological materials is conveniently determined by burning the sample in a stream of oxygen. The sulfur dioxide (as well as the sulfur trioxide) formed during the oxidation is collected by distillation into a dilute solution of hydrogen peroxide ... 

Determination of Combined Sulfur. The sample was decomposed by ignition in an oxygen-filled flask containing 25 ml neutral hydrogen peroxide. The combustion gases were completely absorbed by setting the flask aside for 2 hr. The solution was then boiled to expel carbon dioxide, and the resultant sulfate was determined by alkalimetry. 

When organic compounds containing sulfur are burned, sulfur dioxide is produced. The amount of SO2 formed can be determined by reaction with hydrogen peroxide ... 

A high-temperature combustion method for the determination of sulfur in solid fuels has also been adopted in many laboratories and is advantageous insofar as chlorine can be determined simultaneously. The method requires that the coal sample be heated to 1250°C-1350°C (2280 F-2460°F) in the presence of excess kaolin, ferric phosphate, or aluminum oxide to enhance the ranoval of the sulfur (as sulfate) from the ash. Oxygen is also included to produce oxides of sulfur which are absorbed in hydrogen peroxide (whereby sulfur dioxide is converted to sulfur trioxide). The solution is then titrated with standard alkali solution which gives the total acidity (due to the hydrochloric and sulfuric acids that are formed). 

A long-established procedure for the determination of sulfur dioxide is the Monier-Williams method in which sulfur dioxide is distilled from an acidified solution and the vapor passes through U-tubes containing hydrogen peroxide which oxidizes it to sulfuric acid. The acidity produced is then titrated with dilute standard alkali. This procedure is preferred to an iodimetric titration when volatile sulfur compounds are present as in mustard, onion, and horseradish. Sulfur dioxide may also be... 

Other gases are absorbed and determined by volumetric methods only in special cases. A solution of palladium(II) chloride or colloidal palladium and picric acid absorbs hydrogen, a solution of potassium dichromate is used for sulfur dioxide, and a solution of cadmium acetate or alkaline solution of hydrogen peroxide for hydrogen sulfide. 

To determine sulfur in amounts down to 500 ppm in polyolefins the sample is wrapped in filter paper and burnt in a closed conical flask filled with oxygen at atmospheric pressure. The sulfur dioxide produced in the reaction reacts with dilute hydrogen peroxide solution contained in the reaction flask to produce an equivalent amount of sulfuric acid ... 

A 50.00-mL sample of aqueous Ca(OH)2 requires 34.66 mL of a 0.944-A/ nitric acid for neutralization. Calculate the concentration (molarity) of the original solution of calcium hydroxide. When organic compounds containing sulfur are burned, sulfur dioxide is produced. The amount of SO2 formed can be determined by the reaction with hydrogen peroxide ... 

More methods are available for chlorine. As free chlorine, the element may be analyzed by reduction to chloride using iodide, arsenite, alkaline hydrogen peroxide, sulfur dioxide, or sodium thiosulfate (Na2S203), or determined colorimetrically by treatment with ort/to-toluidine in hydrochloric acid. Chloride ion may be precipitated as silver chloride or titrated with silver nitrate in the presence of potassium chromate (K2Cr04). 

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