Question

How can litmus paper and phenolphthalein be used to tell whether a solution is an acid or a base? Be specific.

Answer 1

Both litmus paper and phenolphthalein are used as acid/base (pH) indicators.

Litmus paper:
Litmus paper will turn either blue or red when a drop of solution is added to the paper. Red indicates an acidic solution (pH is <4.5), and blue indicates a basic solution (pH >8.3).

Phenolphthalein:
Phenolphthalein is commonly used during acid/base titrations. When the solution is acidic and the indicator is added, it will remain colorless. If the solution is basic, the phenolphthalein will turn pink.