What is the final chloride ion concentration when 43. g AlCl3 is dissolved in enough water to make 774. mL of solution? The molar mass of AlCl3 is 133.340 g/mol.

Answer 1

First we need to convert AlCl3 to moles:

43 g AlCl3 x 1 mole AlCl3/ 133.340 g = 0.32 mol AlCl3

Given the molecular formula, we have three chlorine atoms for every mole of AlCl3

0.32 mol AlCl3 x 3 mole Cl^-/ 1 mole AlCl3 = 0.96 mol Cl^-

Now we will divide this by the volume of the solution as liters

774 ml x 1 L/ 1000 mL = 0.774 L

Concentration = 0.96 mol Cl^- / 0.774 L = 1.24 mol / Cl^- L

Answer 2

AlCl₃ ==> Al³⁺ + 3C^l-

43 g AlCl3 x 1 mol/133.34 = 0.322 moles AlCl3

0.322 mol AlCl3 x 3 moles Cl-/mole AlCl3 = 0.966 moles Cl-

0.966 moles Cl-/0.774 L = 1.25 M Cl-