Acids and bases differ in that acids release free hydrogen ions when they are dissolved in water. Bases accept those hydrogen ions and form acid salts.
The power of an acid depends on how much of its hydrogen it releases. Some acids are dangerous to ingest or even place on the skin, while others are necessary for health, such as ascorbic acid. Acids also have a sour taste. They sting when they are placed on open wounds and turn blue litmus paper red.
Most bases have atoms of some metal and at least one -OH, or hydroxyl group. Sodium hydroxide, for example, has a sodium atom and a hydroxyl group, and its chemical formula is NaOH. When diluted with water, bases have a bitter taste, a slippery feel and turn red litmus paper blue. They also break apart into positive and negative ions.
The strength of a base depends on how completely it breaks down when it is placed in solution. A base that is considered strong, such as sodium hydroxide, is referred to as an alkali.
The pH test is used to determine whether a substance is acidic or basic. The pH scale ranges from zero to 14, with seven being neutral. Substances that are lower than seven are acidic, while substances higher than seven are basic.