An acidic solution is a water-based liquid that has a pH level less than 7. It's characterized by an excess of hydrogen ions (H+).
pH Scale: A measure of acidity or alkalinity of water soluble substances. A pH value is a number from 1 to 14, with 7 as the middle (neutral) point.
Hydrogen Ion Concentration: The amount of hydrogen ions in a particular solution, which determines its acidity or alkalinity.
Base Solution: A base or alkaline solution is one that has a pH level greater than 7 and is characterized by an excess of hydroxide ions (OH-).