A water solution which contains magnesium chloride as the only solute measured 232 parts per million chloride on an analytical instrument using a specific ion electrode as the sensor unit. When converted to moles per liter what value would you get for the chloride ion concentration?

Question

A water solution which contains magnesium chloride as the only solute measured 232 parts per million chloride on an analytical instrument using a specific ion electrode as the sensor unit.  When converted to moles per liter what value would you get for the chloride ion concentration?

DrBob222 · Answer

232 ppm = 232 g Cl^-/10^6 g solution =
232 x 10^-6 g Cl^-/g solution. Since the solution is so dilute, the density of the solution will be essentially 1.00 g/mL; therefore, this is equivalent to 232 x 10^-6 g Cl^-/mL or for a liter it is
232 x 10^-6 x (1000 mL/1L) = 232 x 10^-3 g Cl^-/L. Convert that to moles/L to obtain molarity. Check my work.