40. Solution to Chemistry Problem

1. In standard NaF solutions, the electrode potentials of the fluoride-selective electrode relative to the silver chloride electrode were measured and the following data were obtained:
Cf, mol/l 1*10-1 1*10-2 1*10-3 1*10-4 1*10-5
E, mV 100 140 190 230 275
The test solution containing fluoride ion, 10.00 ml in volume, was diluted with water to 50.00 ml and the electrode potential of the fluoride-selective electrode in the resulting solution was measured: Ех=210 mV. Determine the molar concentration (mol/l) of fluoride ion in the test solution.