Question

You are presented with a white solid and told that due to careless labeling it is not clear if the substance is barium chloride, lead chloride, or zinc chloride.when you transfer the solid to a beaker and add water,the solid dissolves to give a clear solution.next a na2so4(aq) solution is added and a white precipitate forms. what is the identity of the unknown white solid?

Answer 1

The given salts are Barium chloride, lead chloride and zinc chloride.

The balanced chemical reaction between barium chloride and sodium sulfate:

$BaCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+BaSO_{4}(s)_{white precipitate}$

The balanced chemical reaction between lead chloride and sodium sulfate:

$PbCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+PbSO_{4}(s)_{white precipitate}$

The balanced chemical reaction between zinc chloride and sodium sulfate:

$ZnCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+ZnSO_{4}(aq)$

Both Barium chloride and lead chloride produce a white precipitate of their respective sulfates upon reaction with sodium sulfate. But BaCl2 is readily soluble in water where as Lead chloride is insoluble in water.

Therefore, the compound is barium chloride.