The Properties of Acids and Bases

Acids are substances that can donate a hydrogen ion (H+), or a proton, to another substance during a chemical reaction.
Litmus paper turns red in the presence of an acid.
Acids react with metals to produce a salt and hydrogen gas following the formula: acid + metal -> salt + hydrogen.
In their reaction with carbonates, acids produce a salt, water, and carbon dioxide following the formula: acid + carbonate -> salt + water + carbon dioxide.
The most common household acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3).

Bases are substances that can accept a hydrogen ion (H+) from another substance.
Most bases are metal oxides or metal hydroxides. Some common examples include zinc hydroxide [Zn(OH)2] and copper(II) oxide (CuO).
Litmus paper turns blue in the presence of a base.
When a base is dissolved in water, it forms an alkali. All alkalis are bases, but not all bases are alkalis.
The reaction between a base and an acid is known as neutralisation, and it results in the formation of a salt and water: acid + base -> salt + water.

Salts are compounds formed when the hydrogen of an acid is replaced by a metal ion or an ammonium ion.
The naming of salts is determined by the acid and base that react. The first part is the metal from the base, and the second part from the acid - e.g., sodium + sulfuric acid = sodium sulphate.
Salts can be made by reacting an acid with a base, a metal or a carbonate.
Crystallisation is a common method used to form a solid salt from a solution. This is achieved by evaporating the water from the solution until the salt starts to crystallize.
Most salts are solid and crystalline in form at room temperature, and they have high melting and boiling points.