In a sodium chloride solution of concentration 0.1 mol / L, what is the concentration of chloride ions in ppm?

3550ppm

A 1 M solution of sodium chloride (NaCl) has a molar mass 35.45 for chloride, which you find from looking up the atomic mass of chlorine on the periodic table and noting there is only 1 Cl ion per NaCl molecule. The mass of sodium doesn't come into play since we're only looking at chloride ions for this problem. So, you now have the relation:

35.45 gram/mole or 35.5 g/mol

You either move the decimal point over one space to the left or multiply this value times 0.1 to get the number of grams in a 0.1 M solution, to give you 3.55 grams per liter for a 0.1 M NaCl solu

tion. 3.55 g/L is the same as 3550 mg/L

Since 1 mg/L is about 1 ppm:

A 0.1 M solution of NaCl has a concentration of about 3550 ppm Cl ions.