Stoiciometry

Question

A solution was prepared by dissolving 4.75g of sodium chloride and 0.575g of calcium chloride in water and diluting to a volume of 500.0mL. What is the molarity of chloride ions in this solution?

Answer 1

Molarity Cl^- = # mole Cl^-/V_solution

# mole Cl- = # mole NaCl + 2 x #mole CaCl₂

# mole NaCl = 4.75 g NaCl x 1mol NaCl / 58.5 g NaCl =0.0812 mol

# mole CaCl2 = 0.575 g CaCl₂ x 1 mol CaCl₂ / 111 g CaCl₂ = 0.00518 mol 

 

# mole Cl- = # mole NaCl + 2 x #mole CaCl₂ = 0.0812 + 2 x 0.00518 = 0.0916 mol

 

 Molarity Cl- = # mole Cl-/V_solution = 0.0916 mol/0.5 = 0.183 M