Determining the Identity of a Solid

Question

Hi,

How do I determine the identity of a solid when I'm only told that it:

1. is soluble in water, and
2. the "solid + water" solution forms a precipitate when it is added to sodium sulfate.

Jackson

Answer 1

Hi Jackson S.,

You can at best say that the data would support the identity of the unknown as the soluble salt of an alkaline earth element, such as CaCl₂ , BaCl₂ and so on. These element cations tend to precipitate with SO₄ because they stack in nicely in a lattice. Look up the "Solublity Product" of the respective sulfate salts to examine which is most insoluble.

-- Cheers, --Mr. d.