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?

A. BaCl₂ (barium chloride)
B. PbCl₂ (lead chloride)
C. ZnCl₂ (zinc chloride)

Answer 1

The unknown white solid is zinc chloride (ZnCl₂).

Step-by-step explanation:

The identity of the unknown white solid can be determined based on the observations made during the experiment. When the solid dissolved in water to give a clear solution, it ruled out the possibility of it being barium chloride (BaCl₂) since BaCl₂ forms a white precipitate when added to water. The formation of a white precipitate when a Na₂SO₄(aq) solution was added suggests that the unknown solid is zinc chloride (ZnCl₂).