ACIDS

ACIDS

A substance which dissolves in water to give hydrogen ions as the only positively charged ions is called an acid. The acids prepared from the minerals of the earth are known as mineral acids.

Eg. Sulphuric Acid, Nitric Acid, Hydrochloric Acid, Phosphoric Acid.

Acids can be classified as strong and weak.

Strong Acids are acids that dissolve in water to give a large number of positively charged hydrogen ions.

Weak Acids are acids that dissolve in water to give a smaller amount of positively charged hydrogen ions.

Concenrated acids have less or no water.

Diluted acids are solutions of acids.

Natural Source

Acid

Oranges and lemons

Citric Acid

Grapes, Tamarind and Goose Berries

Tartaric acid

Tomatoes, Spinach

Oxalic Acid

Sour Milk

Lactic Acid

Vinegar

Acetic Acid

Apples

Malic Acid

Proteins

Amino Acid




Some Common Acids with their formulae

Name

Chemical Name

Formula

Hydrochloric acid

Hydrogen Chloride

HCl

Sulphuric Acid

Hydrogen Sulphate

H2SO4

Nitric Acid

Hydrogen Nitrate

HNO3

Phosphoric Acid

Hydrogen Phosphate

H3PO4

Sulphurous Acid

Hydrogen Sulphite

H2SO3

Nitrous Acid

Hydrogen Nitrite

HNO2

Carbonic Acid

Hydrogen Carbonate

HCO3



General Physical Properties of Acids :

  1. They have a sour taste.
  2. All acids have hydrogen atoms in them.
  3. They turn blue litmus red.
  4. They turn methyl orange solution pink
  5. They donot affect phenolphthalein solution
  6. Strong acids have a corrosive action on skin. They cause painful blisters.
  7. Most of the acids are soluble in water.
  8. Acid solutions are good conductors of electricity.
Uses of Acid :

Sulphuric acid

  • Manufacture of fertilizers
  • Batteries of cars, buses, trucks and inverter batteries.
  • Manufacture of dyes, drugs, paints, plastics, detergents etc.
Hydrochloric Acid

  • Cleaning metal surfaces during timing and galvanising
  • Used in dyeing industry
  • Used for preparing glucose from starch
  • Used for descaling the steam boilers
  • Used in cleaning kitchen sinks and other sainitary ware.
Nitric Acid

  • It is used for manufacture of fertilizers such as Ammonium Nitrate and Calcium Nitrate
  • It is used in manufactures of TNT and TNG.
  • It is used in purification of metals such as gold and silver by goldsmiths
Phosphoric Acid
  • It is used for manufacturing Phosphatic fertilizer
Carbonic Acid
  • It is commonly called plain soda. Mixed with citric acid and sugar, it is used for making soft drinks.
Acetic acid
  • It is used as a table acid and for the preservation of food articles
Tartaric Acid
  • It is used in the manufacture of baking powder

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