Acid – base indicators are dyes or mixtures of dyes which are used to detect the presence of
acids and bases.
Acidic nature of a substance is due to the formation of H+
(aq) ions in solution. Formation of
OH-
(aq) ions in solution is responsible for the basic nature of a substance
When a base reacts with a metal with the evolution of hydrogen gas, a salt is formed.
When an acid reacts with a metal carbonate or metal hydrogen carbonate gives the corresponding
salt, carbon dioxide gas and water.
Acidic and basic solutions in water conduct electricity because they produce hydrogen ions and
hydroxide ions respectively.
The strength of an acid or an alkali can be tested by using a scale called the pH scale (0-14)
which gives the measure of hydrogen ion concentration in a solution.
neutral solution has a pH of 7, while an acidic solution has a pH less than 7 and a basic
solution has a pH more than 7.
Living beings carry out their metabolic activities within an optimal pH range.
Mixing concentrated acids or bases with water is a highly exothermic process.
Acids and bases neutralize each other to form corresponding salts and water.
Water of crystallization is the fixed number of water molecules chemically attached to each
formula unit of a salt in its crystalline form
Salts have various uses in everyday life and in industries.
Refelections on concepts
What is a neutralization reaction? Give two examples.
An acid or a base is mixed with water .Is this process exothermic or endothermic one?
