A chemical analysis of a surface water yields the following data:
Ion Concentration mg/L
Ca^(2+) 90
Mg^(2+) 30
Na^+ 72
K^+ 6
Cl^- 120
SO4^(2-) 225
HCO3^- 165
pH 7.5
Problem: The Cl^- concentration in the water analysis given has been questioned. What concentration of Cl^- (mg/L) would make the cations and anions balance?