Do Lewis acids and bases turn change colour of litmus Well, the question is short. Can lewis acids and bases change the colour of a litmus paper? I can't seem to find the answer online (at least according to my high school level chemistry search history).
The intuitive answer I feel is that they shouldn't be able to, as lewis acids and bases are defined only by their ability to donate or accept electrons. On the other hand, Arrenhius and Broensted-Lowry acids seem to be able to change the colour of litmus, possibly due to the presence of H+ or OH-
As a bonus question, is there any indicators that can be used to test the presence of lewis acids that change their colour after donating a lone pair of electrons?
You should keep in mind that the concept of acid-bases is not restricted to water. Lewis acid definition is applicable to gaseous, aqueous and non-aqueous systems. Consequently, all Bronsted-Lowry acids are Lewis acids. The idea applies to bases. Note that the converse is not true just like an apple is fruit but not all fruits are apples. The idea of litmus test is rather restricted to aqueous systems. So in short, the all relatively strong Lewis acids and bases in water can affect the litmus.
If you put a blue litmus is very dry HCl (gas), it would still turn it red because paper is never dry. It always has moisture absorbed in it.