What are the differences between an acid and a base?

Basis of differentiation

Acid 

Base

Definition 

An acid is a substance with a pH value lower than 7 when present in an aqueous solution 

A base is a substance with a pH value higher than 7 when present in an aqueous solution 

Arrhenius theory

An acid is a substance that increases the concentration of H+ (hydrogen ions) in an aqueous medium

A base is a substance that increases the concentration of hydroxide ions (OH–) in an aqueous medium

Bronsted-Lowry theory

An acid is a substance that donates protons

A base is a substance that accepts protons

Lewis theory

An acid is an electron pair acceptor – it accepts a pair of electrons from a covalent chemical bond

A base is an electron pair donor – it donates a pair of electrons

Dissociation

An acid release H+ (hydrogen ions) when dissolved in water

A base releases OH– (Hydroxide ions) when dissolved in water

Taste 

Is Sour

Is bitter

Odor

Has a burning odor

Is odorless except for ammonia

Touch sensation

Is sticky to the touch

Is slippery to the touch

pH value

The pH value of an acid may range from 1 to 7 

The pH value of a base may range from 7 to 14

Ionization

An acid forms hydronium ions on ionization 

A base forms hydroxyl ions on ionization

Neutralization 

Can be neutralized using a base

Can be neutralized using an acid

Reaction with litmus paper

An acid  will turn blue litmus red but has no reaction with red litmus 

A base will turn red litmus blue but has no reaction with blue litmus

Reaction with Phenolphthalein

An acid remains colorless on adding Phenolphthalein to the solution

A base turns pink on adding Phenolphthalein is the solution

Strength 

The strength of an acid depends on the concentration of hydronium ions

The strength of a base depends on the concentration of hydroxide ions

Chemical formula

The chemical formula of most acids begins with H, for example, Sulfuric acid (H2SO4),

The chemical formula of most bases ends with OH, for example, Potassium Hydroxide (KOH).

Examples

Hydrochloric acid (HCl), Sulfuric acid (H2SO4), Nitric acid (HNO3)

Example: Sodium Hydroxide (NaOH), Potassium Hydroxide (KOH), Caesium Hydroxide (CsOH)

Uses

Acids are used in carbonated drinks, preservatives and fertilizers, as household cleaning agents, for processing leather, and in the manufacture of batteries

Bases are used in the manufacture of gastric medicines such as antacids, toothpaste, soaps, detergents, and paper