I like to do experiments with iron salts, because it's cheap, doesn't require specific equipment and has low toxicity. One more thing I like about these salts is that they have color, which depends on what anion in that salt is, or what complex could be formed.
Here is the iron(II) sulfate solution, which is green.
And this is what happens when I add a few drops of colorless potassium thiocyanate solution.
A new compound is formed, complex salt which is called pentaaqua(thiocyanato-N)iron(II) sulfate.
By this reaction you can make fake blood on your hands...
