Understanding Salts

What is a Salt?

The Two-Part Compound

Salts are the products of neutralisation, composed of a metallic and non-metallic part.
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Key Points

  1. Metallic Part: Comes from the base.
  2. Non-metallic Part: Comes from the acid.
  3. Properties: High melting/boiling points and good electrical conductivity.
  4. Solubility: Some salts dissolve easily; others are insoluble.

Salt Preparation Methods

Three Ways to Salt

Salts can be prepared in the laboratory using three main chemical routes.
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Key Points

  1. Method 1: Neutralisation reaction (Acid + Base).
  2. Method 2: Reaction between an acid and a metal.
  3. Method 3: Action of dilute acids on metal hydroxides, carbonates, or oxides.

Types of Salts

Normal, Acidic, and Basic

Salts can retain acidic or basic properties depending on the replacement of ions.
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Key Points

  1. Normal Salts: Complete neutralisation (e.g., NaClNaCl).
  2. Acidic Salts: Incomplete neutralisation of acid (contains 'H' atom).
  3. Basic Salts: Incomplete neutralisation of base (contains 'OH' group).

Olympiad Fact

Strong Acid + Weak Base results in an Acidic Salt solution.

Hydrated Salts

Water of Crystallisation

Many crystalline salts have a fixed number of water molecules attached to them.
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Key Points

  1. Hydrated Salts: e.g., Blue Vitriol (CuSO4⋅5H2OCuSO_4 \cdot 5H_2O).
  2. Crystallisation: The water molecules maintain the crystal shape and color.
  3. Anhydrous: Salts that have lost their water of crystallisation through heating.

Olympiad Fact

Deliquescent salts (like sodium nitrate) absorb moisture from the air and become wet.

Uses of Common Salts

Beyond the Kitchen

Different salts play diverse roles in our lives, from baking and food preservation to building construction and medicine.
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Key Points

  1. Sodium Chloride: Used for flavoring food, preserving meat/fish, and making washing soda.
  2. Sodium Bicarbonate: Essential for baking (bread/cakes) and as a component of baking powder.
  3. Calcium Carbonate: Used in construction and for the manufacture of cement.
  4. Sodium Benzoate: A critical chemical used for preserving food.
  5. Bleaching Powder: Used for disinfecting drinking water.

Olympiad Fact

Plaster of Paris, chemically known as Calcium Sulphate, is used to immobilize broken bones while they heal.

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