which litmus paper would you use to test for an acid or base? why?

Question

I know you would use a red for an acid and a blue for a base but why....

i mean red for base lol

Answer 1

Litmus is a very general indicator of acidity or alkalinity. In the presence of an alkali it turns blue and in the presence of an acid it turns red.
so to test for acids use the BLUE paper

and

to test for alkalies use the RED paper.

Hope this clarifies it for you.

Answer 2

Use blue for an acid, because it would turn red; use red for a base, because it would turn blue.