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Citric acid is a triprotic acid, with pK a values, extrapolated to zero ionic strength, of 3.128, 4.761, and 6.396 at 25 °C. [21] The pK a of the hydroxyl group has been found, by means of 13 C NMR spectroscopy, to be 14.4. [22] The speciation diagram shows that solutions of citric acid are buffer solutions between about pH 2 and pH 8. In ...
McIlvaine buffer is a buffer solution composed of citric acid and disodium hydrogen phosphate, also known as citrate-phosphate buffer.It was introduced in 1921 by the United States agronomist Theodore Clinton McIlvaine (1875–1959) from West Virginia University, and it can be prepared in pH 2.2 to 8 by mixing two stock solutions.
In the case of citric acid, the overlap is extensive and solutions of citric acid are buffered over the whole range of pH 2.5 to 7.5. Calculation of the pH with a polyprotic acid requires a speciation calculation to be performed. In the case of citric acid, this entails the solution of the two equations of mass balance:
Silver cleaning is a specialty since silver is noble but tends to tarnish via formation of black silver sulfide, which is removable via silver-specific complexants such as thiourea. Stainless steel, nickel, and chromium cleaners contain lactic, citric, or phosphoric acid. A solvent (mineral spirits) may be added.
Rain water contains dissolved carbon dioxide taken from the atmosphere. Some of the dissolved carbon dioxide reacts with the water to form carbonic acid, which remains in solution. Minerals containing calcium and magnesium form soluble bicarbonates when exposed to carbonic acid. Water containing these minerals is known as "hard water".
The speed of the descaling action depends on the concentration and acidity or pH of the solution provided. Hydrochloric acid is much stronger than acetic acid, for example, and therefore tends to remove scale faster. Weak acids such as acetic or citric acids may be preferred, however, where damage to the substrate is to be minimised. [citation ...
A simple buffer solution consists of a solution of an acid and a salt of the conjugate base of the acid. For example, the acid may be acetic acid and the salt may be sodium acetate . The Henderson–Hasselbalch equation relates the pH of a solution containing a mixture of the two components to the acid dissociation constant , K a of the acid ...
The software aqion is shipped with a set of example solutions (input waters) and a tutorial how to attack typical water-related problems (online-manual with about 40 examples). More examples and exercises for testing and re-run can be found in classical textbooks of hydrochemistry. [6] [7] [8]