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 an Na2SO41aq2 solution is added and a white precipitate forms. What is the identity of the unknown white solid?

Video transcript

Hi everyone here we have a question telling us that an announced solid is suspected to be either calcium bromide, mercury bromide or silver bromide when dissolved in water. The resulting solution is clear. A solution of potassium sulfate was then added in a precipitate formed identify the formula of the unknown solid. So we need to remember that our highlights are soluble except when with silver, lead, copper and mercury. So mercury bromide and silver bromide shouldn't dissolve. However, calcium bromide will be present in the solution. Now we need to remember that sulfates are soluble except when with copper, calcium strongly in barium silver and lead. Therefore our unknown solid is going to be calcium sulfate because it will not dissolve. And that is our final answer. Thank you for watching. Bye.