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Bases are the chemical opposite of acids. Acids are defined as compounds that donate a hydrogen ion

(H+) to another compound (called a base). Traditionally, an acid (from the Latin acidus or acere meaning

sour) was any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion

activity greater than inpure water, i.e. a pH less than 7.0. Correspondingly, a base was any compound

that, when dissolved in water, gives a solution with a hydrogen ion activity lower than that of pure water,

i.e. a pH higher than 7.0 at standard conditions.A soluble base is also called an alkali. A reaction between an acid and a base is called neutralization and

this neutralization results in production of water and a salt. Volatile liquids (acids) when mixed with

specific substances turn into salts. These substances form a concrete base and hence the name base

was derived. Acids in general are H+ donors and Bases are H+ acceptors.

Acid BaseDefinition: Arrhenius Definition: An acid is any

chemical compound which when

dissolved in water gives a solution

with a hydrogen ion activity greater

than in pure water. Bronstead Lowry

Definition: An acid is an substance

which donates a proton.

Arrhenius Definition: A base is an

aqueous substance that can accept

hydrogen ions. Bronstead Lowry

Definition: A base is any substance

which accepts a proton.

pH (measure ofconcentration of

hydrogen ions in a solution):

Less than 7.0. Greater than 7.0 and could go up to

14 in case of stronger bases.

Physical characteristics: Depending on the temperature, acids

can occur in solid, liquid or gaseous

form. Taste sour.

Bases feel slippery because of the

reaction of the base with the oils of

your hand. Frequently solids except

ammonia which is a gas. Taste

bitter.

Strength: depends on concentration of thehydronium ions

depends on concentration of thehydroxide ions

Phenolphthalein: remains colorless Makes it pink

Other Properties: Electrolytes, conduct electricity

(because electrolytes), react with

many metals.

Electrolytes, conduct electricity,

ranges from insoluble to so soluble

that they can react with water vapor.

Dissociation: Acids free hydrogen ions (H+) when

mixed with water.

Bases free hydroxide ions (OH-)

when mixed with water.

Chemical Formula: An acid has a chemical formula with

H at the beginning of it. For

example, HCl (Hydrochloric Acid).

There is one exception to his rule,CH3COOH = Acetic Acid (vinegar)

A base has a chemical formula with

OH at the end of it. For example,

NaOH (Sodium Hydroxide).

Examples: Acetic acid i.e.CH3COOH

andSulfuric acid

Sodium Hydroxide (NAOH) and

Ammonia (NH3)

Litmus test: Acids change litmus paper red. Bases change litmus paper blue.

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Properties of acids vs basesBases have a slippery feel on fingers and taste bitter. They change litmus paper blue. Acids taste sour

and create a stinging feeling on the mucous membranes. They change litmus paper red. They can react

with bases to produce salts and water. They both conduct electricity depending on the dissociation of

ions. Acids have a pH lesser than 7.0 and the lower it is, the stronger the acid becomes. Bases have a pHbetween 7 and 14. Higher the pH value,stronger will be the base. A pH level of 7 is a neutral substance

which is water.

Differences in Applications for acids and basesAcids are often used to remove rust from metals, as an electrolyte in batteries, for mineral processing, to

produce fertilizers and gasoline and as additives in food and beverages. Bases are used primarily in

cleaning as dishwashingand laundry detergents, oven cleaners and stain removers.