A Java applet that calculates the amount of acetic acid and sodium acetate necessary to achieve a buffer at a given pH and strength.
How to use
Type the desired pH into the first cell, and type the intended buffer strength (in millimoles per liter) in the second cell. Change the molecular weights if the values for your salts differ from those given.
Press the calculate button, and the approximate masses of anhydrous acetic acid and sodium acetate dihydrate for one liter of solution will be displayed. For example, a pH of about 4.0 with a buffer strength of 10 mM is obtained using 1.3 g acetic acid monohydrate and 1.1g sodium acetate dihydrate. The molar ratios of acetic acid and sodium acetate are given in the Java control panel.
The pK's used for acetate buffer is 4.75. It's best to buffer at a pH close to the pK, so use acetate buffers only in the pH range 3-6.
What buffer strength to use? Too low will give a weak, drifting buffer, while too much may negatively affect other desired properties, such as taste. A 10 mM buffer is in general a good starting point.
Version 1.1, November 19, 2000. Scott
Version 1.0, September 8, 1997. Jeffrey Clymer
The source code
Index of other pages by Jeffrey Clymer