An acid is a compound that is defined by its physical and chemical properties. Acids taste sour and react with metals and polyatomic ions called carbonates. A carbonate is a charged cluster of Carbon and Oxygen atoms. In addition, when tested with blue litmus paper, acids turn the paper red. A base or hydroxide, like an acid, is also defined by its properties. Bases taste bitter, are slippery to the touch and turn red litmus paper blue. An example of a base is NaOH or sodium hydroxide. Read More...