Passage III

The chemical equations in Figure 1 show what occurs when 1 formula unit of each of 3 salts dissolves in H₂O.

The conductivity of a solution is a measure of its ability to conduct electricity. Figure 2 shows how the conductivity (in millisiemens per centimeter, mS/cm) of an 18°C aqueous solution of each of the 3 salts varies with concentration. Concentration is measured as millimoles of salt per liter of solution (mmol/L). A millimole is 6 x 10²⁰ formula units of any salt.

Figure 2 adapted from John A. Dean, Lange's Handbook of Chemistry. @1992 by McGraw-Hill, lnc.

Figure 3 shows how the conductivity of an aqueous NaCl solution at 4 temperatures with concentration (measured as % NaCl by mass).