Copper sulfate-sulfuric acid tests

Intergranular Corrosion Resistance AL 29-4C contains a deliberate titanium addition to stabilize the carbon and nitrogen. AL 29-4C is resistant to intergranular corrosion as determined by the copper-copper sulfate-sulfuric acid tests detailed in ASTM Specification A 763, Practices Y and Z. 

To test the validity of the above equations, Popov et al. [7, 11, 13, 14] carried out experiments on diffusion-controlled metal electrodeposition on a well-defined, triangularly shaped surface profile, through a diffusion layer of well-defined thickness 5 hp. A phonograph disk negative was used as the substrate upon which a layer of an agar-containing copper sulfate-sulfuric acid solution was placed and left to solidify, as illustrated in Fig. 2.3a. 

The electrolyte composition was 0.24 M copper sulfate for the second part of the experiments, we added sulfuric acid. Tests were performed with 0.5-1.5 M of sulfuric acid obtaining the same type of morphology. The solutions were deaerated with bubbling nitrogen before experiments. The depositions were performed at ambient temperature without stirring. The rest of the procedure was similar to that used for Zn electrodeposition, with the necessary modifications. 

The accelerated Strauss test, ASTM A 262 Practice E (copper-copper sulfate-16 % sulfuric acid test), is also a popular quality control test because it is brief (typically 24 h) and includes an acceptance criterion. After exposure, specimens are bent to expose intergranular attack. Material with attack fails, while unattacked material passes. Experience is important in specimen evaluation to separate cracks" due to attacked grain boundaries from mechanical cracks that may have occurred in bending. Different laboratories have obtained varying results upon examination of the same set of sjjecimens [/2]. 

Qualitative Analysis. Nitric acid may be detected by the classical brown-ring test, the copper-turnings test, the reduction of nitrate to ammonia by active metal or alloy, or the nitrogen precipitation test. Nitrous acid or nitrites interfere with most of these tests, but such interference may be eliminated by acidifying with sulfuric acid, adding ammonium sulfate crystals, and evaporating to alow volume. 

KJELDAHL TEST. An analytical method for determination of nitrogen in certain organic compounds. It involves addition of a small amount of anhydrous potassium sulfate to the test compound, followed by healing the mixture with concentrated sulfuric acid, often with a catalyst such ns copper sulfate. As a result ammonia is formed. Alter alkaly/ing the mixture with sodium hydroxide, the ammonia is separated by distillation, collected in standard acid, and the nitrogen determined by back-iilruiion. 

Sulfuric acid, concentrated and dilute Silver nitrate Copper sulfate-pyridine test Cyanates, OCN Vigorous effervescence, due largely to evolution of carbon dioxide, with concentrated acid producing a more dramatic effect Curdy white precipitate of silver cyanate Lilac-blue precipitate (interference by thiocyanates) reagent is prepared by adding 2 or 3 drops of pyridine to 0.25 M CuS04 solution... 

Proteins respond to the following color tests (a) biuret, pink to purple with an excess of alkali and a small amount of copper sulfate (b) ninhydrin. a blue color when boiled with ninhydrin (triketohydrindene hydrate), which is intensified by the presence of pyridine (c) Millon s test for tyrosine, a brick-F color or precipitate when boiled with mercuric nitrate in an excess of nitric acid (d) Hopkins-Cole test for tryptophan, a violet zone with a salt of glyoxylic acid and stratified over sulfuric acid and (e) xanthoproteic test, a brilliant orange zone when a solution in concentrated nitric acid is stratified under ammonia. Almost all so-called alka-loidal reagents will precipitate proteins in slightly acid solution. 

Z Copper Sulfate 16% Sulfuric Acid with metaUic copper boiling 24 h 17-18% Cr Check for fissures in bend test... 

Eliminate the Two Copper Sulfate Tests with 6 % Sulfuric Acid, Practice E in A 262 and Practice Z in ASTM A 763 (Tables 5 and 6) Similar results can be obtained with the 50 % sulfuric acid-copper sulfate tests, Practice F in ASTM A 262 and Practice Y in ASTM A 763. 

A drop of 2 iV sulfuric acid is placed on the surface to be tested, and allowed to react for about a minute. The drop is then taken up on filter paper impregnated with 0.1 % copper sulfate. The fleck on the paper is spotted with a drop of ammonium-mercury thiocyanate solution (see page 498). Zinc is revealed by a violet color. The color is due to the formation of a compound containing Zn[Hg(CNS)4] and Cu[Hg(CNS)4] which, however, does not have the color of a mechanical mixture of these components (see page 219). 

Moneypenny-Strauss test Corrosion testing in a copper sulfate solution containing sulfuric acid used to detect the susceptibility of stainless steel to intergranular corrosion. 

Describe any similarities and differences you observe when looking at a test tube of dilute sulfuric acid and a test tube of 0.05 mol dm" copper(ll) sulfate solution. 

Once they have reached higher pH, reducing conditions of the intestinal tract (Davis et al, 1992), sulhdes should be more stable, and may actually precipitate if reduced sulfur is present. Other solids, such as hydroxides or hydroxy-sulfates of aluminum, and possibly iron, may also precipitate. The increased pH should also lead to the increased sorption onto particulates of various metals and metalloids such as lead and copper (Smith, 1999). However, in vitro tests (Ruby et al, 1993) indicate that the increased complexing with unprotonated organic acids and enzymes helps offset the pH-driven precipitation and sorption of the base metals that were dominantly chloride-complexed in the stomach fluids. Arsenic and other oxyanionic species are likely to be sorbed as the stomach acids are neutralized, but may be partially desorbed once higher pH values are reached in the intestine (Ruby et al, 1996). 

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