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Citric acid is a useful component of a buffer mixture because it has three pK a values, separated by less than two. The buffer range can be extended by adding other buffering agents. The following mixtures (McIlvaine's buffer solutions) have a buffer range of pH 3 to 8. [7]
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.
This mixture consists of 0.0286 M citric acid, 0.0286 M monopotassium phosphate, 0.0286 M boric acid, 0.0286 M veronal and 0.0286 M hydrochloric acid titrated with 0.2 M sodium hydroxide. The buffer was invented in 1931 by the English chemist Hubert Thomas Stanley "Kevin" Britton (1892–1960) and the New Zealand chemist Robert Anthony Robinson ...
Acid-citrate-dextrose or acid-citrate-dextrose solution, also known as anticoagulant-citrate-dextrose or anticoagulant-citrate-dextrose solution (and often styled without the hyphens between the coordinate terms, thus acid citrate dextrose or ACD) is any solution of citric acid, sodium citrate, and dextrose in water.
Outside the transition range the concentration of acid or conjugate base is less than 10 % and the colour of the major species dominates. Species concentrations calculated with the program HySS for a 10 mM solution of citric acid. pK a1 = 3.13, pK a2 = 4.76, pK a3 = 6.40. A weak acid may be defined as an acid with pK a greater than
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 ...
For this reason, organic acids are used at high temperatures or when long contact times between acid and pipe are needed. [citation needed] The conjugate bases of organic acids such as citrate and lactate are often used in biologically compatible buffer solutions. Citric and oxalic acids are used as rust removal.