Question

Aqueous solutions sodium sulfate and copper (II) chloride were mixed together. The precipitate obtained during this reaction was dried and weighed to be 0.5665 g. How much copper (II) chloride in grams was used up during this reaction?

Answer 1

Ans. Balanced Reaction:      CuCl₂(aq) + NaSO₄(aq) --------> CuSO₄(s) + 2 NaCl(aq)

During the reaction, CuSO₄ is precipitated.

# Given, mass of precipitate = 0.5665 g

So, mass of CuSO₄ precipitated = 0.5665 g

Moles of CuSO₄ precipitated = Mass / Molar mass

= 0.5665 g / (159.6096 g / mol)

= 0.003549 moles

# According to stoichiometry of balanced reaction, 1 mol CuCl₂ forms 1 mol CuSO₄.

Therefore,

            Moles of CuCl₂ in sample = Moles of CuSO₄ precipitated = 0.003549 mol

Now,

Mass of CuCl₂ in sample = Moles x Molar mass

                                    = 0.003549 mol x (134.4514 g/ mol)

                                    = 0.4772 g

Therefore, mass of CuCl₂ in sample = 0.4772 g