When an acid is been reacted with a metal, then a salt and hydrogen gas is formed. That is:
For example, on the reaction of a dilute sulphuric acid with zinc metal results in the formation of zinc sulphate and hydrogen gas:
REACTION OF ACIDS WITH CARBONATES OR METAL
On reaction of an acid with metal carbonate (or metal hydrogencarbonates), results in the formation of salt, carbon dioxide gas and water:
For example: When dilute hydrochloric acid reacts with sodium carbonate, then sodium chloride, carbon dioxide and water are formed. This reaction is depicted as:
Note that here, carbon dioxide gas is been formed in the form of brisk effervescence (the rapid escape of small bubbles of gas from the liquid).
REACTION OF ACIDS WITH BASES (OR ALKALIS) (NEUTRALIZATION):
Mixing of an acid and a base together result in the formation of salt and water.
Here, when an acid is been treated with a base, the base neutralises the acid and destroys its acidity.
Since an acid and a base is been neutralised to form water and salt, the process is known as neutralization reaction.
Example: When hydrochloric acid reacts with sodium hydroxide solution, then a neutralization reaction takes place to form sodium chloride and water:
The reaction can be depicted as :
REACTION OF ACIDS WITH METAL OXIDES TO FORM SALT AND WATER:
Acid react with metal oxides to form salt and water. This is given by:
Example: Dilute hydrochloric acid reacts with copper (II) oxide (metal oxide) to form copper (II) chloride and water:
WHAT DO ALL ACIDS HAVE IN COMMON?
An acid is a substance which dissociates (or ionises) on dissolving in water to produce hydrogen ions [H+ (aq) ions].
The presence of charged particles i.e. ions in aqueous solution leads to electric conductivity.
Due to the absence of ions, glucose solution and alcohol solution do not conduct electricity.
In the absence of water, a substance will not form hydrogen ions and hence will not show its acidic behaviour.
USES OF MINERAL ACIDS IN INDUSTRY
Mineral acids are used in many sectors of the chemical industry.
Sulphuric acid is used in the manufacture of fertilizers like ammonium sulphate, paints, dyes, chemicals, plastics, synthetic fibres, detergents, explosives and car batteries.
Nitric acid is used for making fertilizers like ammonium nitrate, explosives like TNT: Tri-Nitro- Toluene, dyes and plastics.
Hydrochloric acid is used for removal of oxide film from steel objects before they are galvanized. They for used for removing ‘scale’ deposits from inside the boilers. It is also used in dye-stuffs, textile, and food and leather industries.