pH

Finding Acids and Bases

Every liquid you see will probably have either acidic or basic traits. So what makes an acid or a base? Originally, acids and bases were defined only by properties like the fact that acids taste sour and turn certain plant dyes from one color to another, while bases taste bitterand change the colors of the same plant dyes in the opposite direction.  Check out this colorful chemistry challenge from Scientific American's Activity Buddies program.

A NOTE ABOUT ACIDS AND BASES:

In 1887, a chemist named Svante Arrhenius came up with a way to define acids and bases. When you put molecules into water, sometimes: 

   • sometimes they break down and release a hydrogen ion H⁺
   • sometimes they break down and release an OH^- (hydroxide) ion

When a hydrogen ion is released, the solution becomes acidic. When a hydroxide ion is released, the solution becomes basic. Today, scientists use something called the pH scale to measure how acidic or basic a liquid is. )