Demal solution

DEMAL SOLUTION, A solution which contains one gram-equivalent of solute per cubic decimeter of solution. It is slightly weaker than a normal solution, in the ratio of the magnitude of the liter to the cubic decimeter. 

The measured resistance of a cell containing a 0.1 demal solution of potassium chloride at 25 , in water having a specific conductance of 0.8 X 10 ohm cm."S was found to be 3468.86 ohms. A 0.1 n solution of another salt, dissolved in the same conductance water, had a resistance of 4573.42 ohms in the same cell. Calculate the specific conductance of the given solution at 25 . 

The potassium chloride solutions employed in the most recent work contain 1.0, 0.1 or 0.01 mole in a cubic decimeter of solution at 0 , i.e., 0.999973 liter these solutions, designated as 1.0 d, 0.1 d and 0.01 d, where d stands for demal, contain 76.627, 7.4789 and 0.74625 grams of potassium chloride to 1000 grams of water, respectively. The specific conductances of these solutions at 0 , 18 and 25 are quoted in Table VII 2 the particular solution chosen for calibrating a given cell depends... 

Values of xrfor 0.01 and 0.1 demal standard KCl solutions are reported from 0 to 50°C (Wu and Koch, 1991). To estimate the cell constant at higher temperatures the authors use temperature correction fectors to correct for the thermal expansion of the materials used in its construction. Temperature correction factors within 0.1 to 0.4% are reported in the bibliography for different cells used in the temperature range from 298 to 673 K. 

If this procedure is not foimd to be reliable one could perform a direct calibration at high temperature by resorting to the available high precision data for the conductivity of KCl solutions up to 410 °C and 33 MPa (Ho et al, 2000). This data are more precise than those reported in 1970 for aqueous 0.01 demal KCl solutions as reference solutions for electrical conductance measurements to 800 °C and 1200 MPa. (Quist el al, 1970). 

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