When something has a pH value of 7, we say it is neutral , that is, it is neither acidic nor basic. In this laboratory activity, you will explore the acidity of three gases that are important in atmospheric chemistry. Others occur naturally. There is one more idea you need to understand before beginning. That is the idea of indicators .
Indicators are organic molecules that turn different colors in acidic and basic solutions.
You may have used litmus paper in some other science class. This substance is red in an acid and blue in a base. Indicators are useful because they tell us if a solution is acidic or basic. You will recall that some acids and bases do not dissociate completely in water. Generation of Gases.