Acids and bases

In chemistry, a compound could be an acid or a base. Acids and bases are very important in chemistry. They describe a large class of substances. Understanding their properties allows us to rationalize patterns that occur in chemistry.

Contrasting properties of acids and Alkalis
Here is a list which contrasts their properties:
 * Acids turn blue litmus paper red. Bases turn red litmus paper blue.
 * Acids give off H+ (Hydrogen) ions in water; bases give off OH- (Hydroxide) ions in water.
 * Acids generally taste sour due to the sour H+ ion; bases taste bitter due to the OH- ion; but they may have other tastes depending on the other part of the molecule.
 * Bases are usually soapy in nature.
 * Acids corrode active metals ; Bases denature protein.
 * Acids have a pH less than 7 ; Bases have a pH greater than 7

Similar properties of acids and Alkalis
Here is a list of properties that are common to both acids and bases
 * When you dissolve an acid or base in water, it makes ions. This makes the water conduct electricity better.
 * The stronger the acid (or base), the more ions are produced, so the conductivity of the solution increases.
 * They can both conduct electricity.
 * When an acid reacts with a base, a salt is formed
 * They both can carry and share ions

Things unique to acids
Acids react with group 1 and 2 metals to generate hydrogen gas.

Examples of common things which are acidic

 * Citrus fruits (Oranges, Lemons, Limes)
 * Apples
 * Pineapples
 * Mangoes
 * Water and soft drinks (Carbon dioxide reacts in water to form carbonic acid)
 * Stomach acids
 * Vinegar
 * Liquid Drain cleaners containing sulfuric acid (Rooto)
 * Any sour candy

Things unique to Alkalis (bases)
Bases feel slippery and soapy and taste bitter because they hydrolyze the fatty acid ester of the skin (saponification reaction).

Examples of common things which are Alkalis

 * Lye
 * Baking soda
 * Bleach
 * Ammonia, e.g. window cleaner
 * Wasp's sting
 * Some Drain cleaner (Drano, Red Devil)
 * Tooth paste