Question

Does ph paper work on metals?

Answer 1

Yes, if they're in liquid form.

Explanation:

Ph paper do work on metals if they are in liquid form, you cant but ph paper on a solid material and it gives you an indication.

Answer 2

I'm not entirely clear on what you mean by "work on".......

Explanation:

I am assuming that you are referring to universal indicator paper, which gives a colour based indication of pH when it is placed into a specific liquid.

If so, then it will only "work" (give a pH indication) if the liquid that you dip it into actually possesses a pH, and to do that it needs to be an aqueous solution containing either hydroxonium (`H_3O^+`) or hydroxide (`OH^-`) ions, or both.

If it is a liquid that does not contain such ions in aqueous solution (e.g. something like motor oil) then pH doesn't apply. Most metals are not liquids at ambient conditions, so you could not physically dip pH paper into them in any case. If you take the one metal that is liquid at room temperature, mercury, then it also does not exhibit a pH because it is not an aqueous solution containing either hydroxonium (`H_3O^+`) or hydroxide (`OH^-`) ions.