Sulphate tests

The evaluation of heat treatments or the effectiveness of stabilisation by limiting carbon content of these stainless steels can be determined by subjecting specimens to the ASTM standardised acid copper sulphate test or boiling nitric acid test (ASTM A262 1986 see also Sections 9.5 and 1.3). 

Acid copper sulphate test t 16 wt.% H2SO4 -1-100 g/l CuSO, (-1- metallic copper) 72 h exposure to boiling solution 1. Appearance of sample upon bending 2. Electrical resistivity change 3. Change in tensile properties -1- 0-30 to -1- 0-58 Chromium-depleted area... 

Ammonium tetrathiocyanatomercurate(II)-copper sulphate test. The faintly acid (sulphuric acid or acetic acid) solution is treated with 0-1 ml 0 25m copper sulphate solution, followed by 2 ml ammonium tetrathiocyanatomercurate(II) reagent. A violet precipitate is obtained. The test is rendered still more sensitive by boiling the mixture for 1 minute, cooling and shaking with a little amyl alcohol the violet precipitate collects at the interface. Iron salts produce a red colouration this disappears when a little alkali fluoride is added. 

Ammonium tetrathiocyanatomercurate(II)-cobalt sulphate test This test is similar to that described under reaction 8, except that a minute amount of a dilute solution of a cobalt salt (nitrate, sulphate or acetate) is added. Coprecipitation of the cobalt tetrathiocyanatomercurate(II) yields a blue precipitate composed of mixed crystals of Zn[Hg(SCN)4] + Co[Hg(SCN)4], Iron(II) salts give a red colouration but this can be eliminated by the addition of a little alkali fluoride (colourless [FeF6]3- ions are formed). Copper salts should be absent. 

Sodium nitroprusside-zinc sulphate test Sodium nitroprusside solution reacts with a solution of a zinc salt to yield a salmon-coloured precipitate of zinc nitroprusside Zn[Fe(CN)5NO], The latter reacts with moist sulphur dioxide to give a red compound of unknown composition the test is rendered more sensitive when the reaction product is held over ammonia vapour which decolourizes the unused zinc nitroprusside. 

Aniline sulphate test, (C6H5.NH2)2H2S04 A small quantity of the solid chlorate (say, 0 05 g) (DANGER) is mixed with 1 ml concentrated sulphuric acid, and 2-3 ml aqueous aniline sulphate solution added a deep-blue colour is obtained (distinction from nitrate). 

Manganese (II) sulphate test If a bromate solution is treated with a little of a 1 1 mixture of saturated manganese(II) sulphate solution and m sulphuric acid, a transient red colouration (due to manganese(III) ions) is observed. Upon concentrating the solution rapidly, brown, hydrated manganese dioxide separates. The latter is insoluble in dilute sulphuric acid, but dissolves in a mixture of dilute sulphuric and oxalic acids (difference from chlorates and iodates, which neither give the colouration nor yield the brown precipitate). 

Lead sulphate test Hydrogen peroxide converts black lead sulphide into white lead sulphate ... 

Sulphate test To 2 ml of the soda extract add dilute hydrochloric acid until acid (test with litmus paper) and then add 1-2 ml in excess. Boil for 1-2 minutes to expel carbon dioxide completely, and then add about 1 ml barium chloride solution. A white precipitate indicates sulphate. Confirm by the charcoal test (Section IV.24, reaction 1). 

Alternatively, the Diencuprato(II)-sulphate test, Section III.8, reaction 8, may be applied to the neutral or slightly ammoniacal solution. 

Ferrocyanide test on stomach contents, 5 Ferrous iron, test on stomach contents, 5 Ferrous Sulphate (test), 133 Fertodur, 500... 

Loffler H, Becker D, Brasch J, et al. Simultaneous sodium lauryl sulphate testing improves the diagnostic validity of allergic patch tests. BrJDermatol 2005 152(4) 709 19. 

Ammonium tetrathiocyanatomercurate(II)-copper sulphate test Acidify the solution faintly with a few drops of m sulphuric or 2m acetic acid. Add... 

Lead sulphate test white lead sulphate ... 

Sodium Sulphate. See salt cake. Sodium Sulphate Test. A test claimed to indicate the resistance of a clay building material to frost action. The test-piece is soaked in a saturated solution of sodium sulphate and is then drained and dried the cycle is repeated and the test-piece is examined for cracks after each drying. The principle underlying the test is that the stresses caused by the expansion of sodium sulphate as it crystallizes are, to some extent, similar to the stresses caused by water as it freezes. The test... 

Chemical analysis on acidified sample. If gas evolves during acidification Moisten lead aeetate paper and place over cell. A brown color is a positive test for H2S (a sign of sulphate-reducing bacteria). Negative test suggests gas is probably CO2 from CaCOs. When possible run iron, alumina, barium sulphate tests. 

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