Chapter 16 Reference
16.1 pH measurement
F-52, 53, 54, 55 219
● Using standard solutions
Standard solutions are used to calibrate the scale of the pH meter employed to measure the
unknown pH of a solution. Standard solutions of pH 4, 7, and 9 are used in combination
according to the particular conditions of the solution that is to be inspected
When the approximate pH value is desired (1-point calibration)
Use the pH 7 standard solution or a standard solution that approximates the pH value of the
solution that is to be inspected.
When it is known beforehand whether the test solution is acidic or alka-
line (2-point calibration)
Acidic: Use the pH 4 and 7 standard solution.
Alkaline: Use the pH 7 and 9 standard solution.
When an unknown solution is to be inspected (3-point calibration)
Use the pH 4, 7, and 9 standard solution.
Others
When finding the pH of other solutions, perform 2-point or 3-point calibration using pH 2, 4,
7, 9, or 12 standard solutions randomly, then measure the test solution.
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