The word acid comes from the Latin word acere, which means sour.   In dilute concentrations acids are responsible for the sour taste of lemons, limes, vinegar and other substances. Hydrochloric acid is produced in your stomach to help digest food. Sulfuric acid is found in car batteries. Acids can conduct an electric current. Acids are also corrosive. When acids react with metals they form hydrogen gas. When an acid reacts with a carbonate it forms carbon dioxide, water, and a salt. Acids can cause skin to burn so you should be careful when handling acids

      Acids can be classified according to the number of hydrogen atoms available to react with a base and degree of ionization (how many of the available hydrogen atoms dissociate in water).
      A base is most commonly thought of as an aqueous substance that can accept hydrogen ions. Bases are also the oxides or hydroxides of metals. A soluble base is also often referred to as an alkali if hydroxide ions are involved.
      Indicators are very special chemicals; they will change color if you change the pH (by adding acid or alkali).

      |Indicator                         |pH                                 |Color in Acid                     |Color in Alkali                   |
|                                   |7.0                               |Red                               |Blue                               |
|Litmus                             |                                   |                                   |                                   |
|                                   |9.7                               |Colorless                         |Red / Pink                         |
|Phenolphthalein                   |                                   |                                   |                                   |
|                                   |3.7                               |Red                               |Yellow                             |
|Methyl Orange...