Apologies for the question which is far below the brilliance of the minds on this page. I have an A-Level in Organic Chemistry but I'm tying myself in knots with this one.
I'm a magician looking to create a Russian Roulette effect with water and acid (sort of!) the actual secret is that both solutions are water.
Is there a readily available metal; or substance that looks like metal, that would make the water behave like an acid to convince an onlooker that it is a potentially life threatening acid.
As a bonus question – is there a way to cheat the litmus test so that one solution (also water!) turns it red, the other reacting neutrally (that's the easy one!)?