Identification Of Ions

Somewhere in every school laboratory there is a bottle whose label has peeled off. Inside is a white powder. It could be sodium chloride, it could be barium sulfate, it could be one of two dozen other things, and no amount of staring at it will settle the question. Yet a chemist with three reagents and a clean wire can name both halves of that compound inside ten minutes, without a single instrument more expensive than a Bunsen burner. That is the trick this lesson teaches you.

The method works because ions announce themselves. Heat certain metal ions and they glow in a colour that belongs to them alone. Offer others a hydroxide ion and they drop out of solution as a solid whose shade gives them away. Negative ions are quieter but just as findable, if you know which reagent to reach for and, crucially, which acid to add first. This is also the one chemistry topic on this course that carries a required practical of its own, so by the end you should be able both to run the tests and to take a page of somebody else's observations and write down the salt that produced them.