Many of the interactions that environmental scientists study are the result of acid and base reactions. So what are acids and bases, anyway? Empirically speaking, acids and bases have the following characteristics:
Acids usually have a sour taste (like lemon juice) and will burn your skin.
Bases usually have a bitter taste and feel slippery (like detergent).
Chemically speaking, an acid is a compound that gives away or releases a hydrogen ion (H+) during a chemical reaction, and a base is a compound that captures a hydrogen ion during a chemical reaction.
The slight polarity of a water molecule makes it a powerful agent for dissolving acid and base compounds into liquid form, or solution. When water dissolves an acid compound, the compound releases positively charged ions of hydrogen (H+) into the solution.
The number of available hydrogen ions in the solution determines how it will chemically react with other compounds. Scientists quantify the concentration of hydrogen ions in a solution by using the pH scale.
The pH scale measures how acidic a solution is, from 1 to 14. Lower numbers indicate higher levels of acidity (more available hydrogen ions), while higher numbers indicate more basic solutions. A pH value of 7 is neutral, meaning that the solution is neither acidic nor basic.