Salts are the ionic compounds which are produced after the neutralization reaction between acid and base. Salts are electrically neutral. There are number of salts but sodium chloride is the most common among them. Sodium chloride is also known as table salt or common salt. Sodium chloride is used to enhance the taste of food.
Characteristics of salt:
- Most of the salts are crystalline soild.
- Salts may be transparent or opaque.
- Most of the salts are soluble in water.
- Solution of the salts conducts electricity in their molten state also.
- The salt may be salty, sour, sweet, bitter and umami (savoury).
- Neutral salts are odourless.
- Salts can be colourless or coloured.
Neutral, Acidic and Basic Salts:
- Neutral Salt:
Salts produced because of reaction between a strong acid and strong base are neutral in nature. The pH value of such salts is equal to 7, i.e. neutral.
Example : Sodium chloride, Sodium sulphate. Postassium chloride, etc.
- Acidic Salts:
Salts which are formed after the reaction between a strong acid and weak base are called Acidic salts. The pH value of acidic salt is lower than 7. For example Ammonium sulphate, Ammonium chloride, etc.
Ammonium chloride is formed after reaction between hydrochloric acid (a strong acid) and ammonium hydroxide (a weak base).
- Basic Salts:
Salts which are formed after the reaction between a weak acid and strong base are called Basic Salts. For example; Sodium carbonate, Sodium acetate, etc.
Sodium carbonate is formed after the reaction between sodium hydroxide (a strong base) and carbonic acid (a weak acid).
The water of Crystallization:
Many salts contain water molecule and are known as Hydrated Salts. The water molecule present in salt is known as Water of crystallization.
Examples:
Copper sulphate pentahydrate (CuSO4.5H2O): Blue colour of copper sulphate is due to presence of 5 molecules of water. When copper sulphate is heated, it loses water molecules and turns: into grey – white colour, which is known as anhydrous copper sulphate. After adding water, anhydrous copper sulphate becomes blue again.
Some Important Compounds and their Uses:
Common Name | Chemical Name | Chemical formula | Uses |
Washing soda | Sodium carbonate decahydrate | Na2C03.10H2O | Manufacture of borax, caustic soda, softening of hard water |
Baking soda | Sodium hydrogen carbonate | NaHCO3 | Used as antacid, ingredient of baking powder |
Bleaching powder | Calcium oxychloride | CaOCl2 | Bleaching clothes, used as oxidising agent, disinfecting water,manufacture of chloroform |
Plaster of paris | Calcium sulphate hemihydrate | CaSO4.1/2H2O | Plastering fractured bones, making toys, decorative materials, statues |
