Given an unknown substance, how could you test to see if it is an acid or a base?
Weak acids and bases are typically very smelly like ammonia and acetic acid, so this is a situation where “the nose knows”. Strong acids and bases can be diluted for safety and then tested with the senses. If the solution leaves the skin with a slick, greasy feeling, it is a base. If the material has a sour taste, it is an acid. Chemists use indicators to test acids and bases. Indicators change color depending on the pH. The pH scale is a measure of how acidic or basic a substance is. Of course the easiest method is to just use a pH meter. The scale runs from 0 to 14. 7 is neutral and anything less is acid. Anything more is basic.