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APPENDIX A
APPENDIX A. PREPARING SALT SOLUTIONS
Verification standards are specially prepared,unsaturated salt solutions with a specific
molality and water potential value that are accurately measurable. METER has verification
standards that are produced under a strict quality assurance regimen. It is also possible to
make verification standards that can read accurately if proper care is taken while preparing
the salt solutions. Table 5 shows the necessary concentrations to mix salt solutions to
achieve ranging water potentials. It is important to use ultrapure water when preparing
your own unsaturated salt solutions.
Table 5 show the water potential at given concentrations of sodium chloride (NaCl) and
potassium chloride (KCl) at 20 °C.
Table 5 Water potential of NaCl and KCl
Concentration
(mol/kg)
NaCl
(MPa)
KCl
(MPa)
0.05 -0.232 -0.232
0.10 -0.454 -0.452
0.20 -0.901 -0.888
0.30 -1.349 -1.326
0.40 -1.793 -1.760
0.50 -2.242 -2.190
0.60 -2.699 -2.622
0.70 -3.159 -3.061
0.80 -3.618 -3.501
0.90 -4.087 -3.931
1.00 -4.558 -4.372