9 REFERENCE
160
Types of pH standard solutions
When measuring pH, the meter must be calibrated using a standard solution. There are
several kinds of standard solutions. For normal measurement, two standard solutions
(with a pH of 7 and 9) are sufficient to accurately calibrate the meter.
9.7
Conductivity Measurement
“Conductivity” is an index that expresses the ease with which electric current flows through a
material. Conductors are categorized either as “electron conductors,” such as metals and
other substances which use free electrons to conduct electricity, or “ion conductors,” such as
electrolytic solution or fused salt, which use ions to conduct electricity. This section deals with
the kind of conductivity that pertains to ions, especially the conductivity of electrolytic solution
that uses water as the solvent. As shown in Fig. 2, two pole plates with an area A (expressed
in m
2
) are positioned parallel to each other, separated by distance l (expressed in m), then
solution is poured into the cell until full and alternating current is run between the plates.
Fig. 2 Conductivity cell imitative
pH 1.68 standard solution: Oxalate
0.05 mol/L tetra-potassium oxalate aqueous solution
pH 4.00 standard solution: Phthalate
0.05 mol/L potassium hydrogen phthalate aqueous solution
pH 6.86 standard solution: Neutral
phosphate
0.025 mol/L potassium dihydrogen phosphate, 0.025 mol/L
sodium dihydrogen phosphate aqueous solution
pH 9.18 standard solution: Borate
0.01 mol/L tetra-sodium boric acid (boric sand) aqueous solution
pH 12.45 standard solution: Saturated
calcium hydroxide solution
Saturated hydrogenated calcium solution
Solution
Polar plates a m
2
x2
Summary of Contents for TW-100
Page 1: ...Water Distribution Monitor TW 100 Instruction Manual CODE GZ0000080187H ...
Page 8: ......
Page 174: ......