the dissociation of both salts NaCl and CaCl₂ are as follows; NaCl --> Na⁺ + Cl⁻
CaCl₂ --> Ca²⁺ + 2Cl⁻
the molar ratio of NaCl to Cl⁻ is 1:1 therefore number of NaCl moles is equal to number of Cl⁻ ions dissociated from NaCl then number of Cl⁻ ion moles - 0.233 mol/L x 0.1000 L = 0.0233 mol
molar ratio of CaCl₂ to Cl⁻ ions is 1:2 1 mol of CaCl₂ gives out 2 mol of Cl⁻ ions. number of CaCl₂ moles - 0.150 mol/L x 0.2500 L = 0.0375 mol then the number of Cl⁻ ion moles - 0.0375 x 2 = 0.0750
total number of Cl⁻ ion moles = 0.0233 mol + 0.0750 mol = 0.0983 mol volume of solution - 100.0 + 250.0 = 350.0 mL
concentration of Cl⁻ = 0.0983 mol / 0.3500 L = 0.281 M concentration of Cl⁻⁻ is 0.281 M
