Ignition residue

Commercial Hquid sodium alumiaates are normally analyzed for total alumiaa and for sodium oxide by titration with ethylene diaminetetraacetic acid [60-00-4] (EDTA) or hydrochloric acid. Further analysis iacludes the determiaation of soluble alumiaa, soluble siHca, total iasoluble material, sodium oxide content, and carbon dioxide. Aluminum and sodium can also be determiaed by emission spectroscopy. The total iasoluble material is determiaed by weighing the ignited residue after extraction of the soluble material with sodium hydroxide. The sodium oxide content is determiaed ia a flame photometer by comparison to proper standards. Carbon dioxide is usually determiaed by the amount evolved, as ia the Underwood method. 

In all the above methods the element is weighed as the oxide, BeO, which is somewhat hygroscopic [compare aluminium(III) oxide]. The ignited residue, contained in a covered crucible, must be cooled in a desiccator containing concentrated sulphuric acid or phosphorus(V) pentoxide, and weighed immediately it has acquired the laboratory temperature. 

Use of a rusty iron tool on an aluminium compressor piston caused incendive sparks which ignited residual propene-air mixture in the cylinder. 

Cool the crucible in a desiccator and weigh. Add to the ignited residue 5 ml coned hydrofluoric acid one drop coned sulfuric acid. Evaporate the acid, ignite the residue, cool in a desiccator and weigh. The difference in wt before and after adding HF is due to the loss of silica... 

In this method, the herbage is first dried at 50 °C for 48 hours and milled to pass though a 0.5 mm screen. Ground material (1 g) is combined with magnesium nitrate solution, which acts as an ashing acid, and the mixture is ignited at 200 °C for 30 minutes and then at 450 °C for 5 -15 hours. The ignited residue is treated with potassium iodide and then dissolved in concentrated hydrochloric... 

Residue on ignition. When dipyridamole is tested according to General Method (281), it contains not more than 0.1% of non-ignitable residue. 

Filtrate contains Fe, Ni, and traces of Au and Rh. Evaporate to dryness with HNOs. Ignite. Wash out Fe and Ni with HCl. Ignite residue of Au and Rh, and... 

This dilemma can be resolved partly by treating the minerals with hydrochloric acid. Carbonates dissolve, whereas silica and combustible matter do not. But the presence of bitumen and even vegetal matter interferes more or less with the reaction with hydrochloric acid, so the cleanest way to carry out acid treatment is on ignition residues. The ratio of acid solubles to ignition loss will then be below 56 44 in proportion to the amount of combustibles present. But because some common minerals dissolve in hydrochloric acid whereas other do not, the conventional method of mineral analysis is approximate at best. 

I.2.2. Soluble salts Add 150 mL of water to 10.0 g of magnesium silicate, heat on a water bath for 60 min with occasional shaking, then cool, dilute with water to 150 mL, and centrifuge. Dilute 75 mL of the resultant transparent liquid with water to 100 mL, and use this solution as the sample solution. Evaporate 25 mL of the sample solution using a water bath to dryness, and ignite the residue at 700 °C for 2 h the mass of the ignited residue is not more than 0.02 g. 

Copper chromite (Lazier catalyst). Supplier Harshaw (CU-0202P 556-002). For preparation of the catalysC an aqueous solution of barium nitrate and cupric nitrate trihydrate is stirred during addition of a solution of ammonium chromate, prepared from ammonium dichromate and aqueous ammonia. The reddish brown precipitate of copper barium ammonium chromate is washed and dried and decomposed by heating in a muffle furnace at 350-450 . The ignition residue is pulverized, washed with 10% acetic acid, dried, and ground to a fine black powder. 

A solution of ammonium chromate is prepared by dissolving 126 g. (0.5 mole) of c.p. ammonium dichromate in 600 cc. of distilled water and adding 150 cc. of 28 per cent aqueous ammonia (sp. gr. 0.9) (Note 3). The warm solution of the nitrates is stirred (hand stirring is adequate) while the ammonium chromate solution is poured into it in a thin stream. The stirring is continued for a few minutes, after which the reddish brown precipitate of copper barium ammonium chromate is collected (Note 4) and pressed in a i6-cm. Buchner funnel, and dried at 110°. This dry precipitate is placed in a loosely covered nickel pan (Note 5), or one or two small porcelain casseroles covered with watch glasses, and heated in a muffle furnace for one hour at 350-450° (Note 6). At this point the yield of chromite should be about 160 g. The ignition residue is pulverized in a mortar to break up any hard lumps that may be present (Note 7) and... 

Example PS N 2000 with 10 mass % Printex XE-2 Amount weighed out 3.3494 g Pyrolysis residue 0.4154 g or 12.40% of amount weighed out Ignition residue 0.0063 g or 0.19% of amount weighed out Corrected pyrolysis residue 12.21% Subtracting concentration shows that 2.21% of the amount weighed out was not decomposed... 

Qualitative spectral analysis or qualitative X-ray fluorescence analysis of the ignition residue for the determination of heavy metals... 

After being weighed, the dish with the evaporation residue is heated (ignited) at 30 °C for 1 hour. If the ignited residue has a brown or black coloration (due to organic substances), it should - after cooling - be... 

The difference in weight between the evaporation residue and the ignition residue is the loss on ignition. 

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