More About Salts

Key Notes:

Definition of Salts:

  • Salts are ionic compounds formed by the neutralization reaction between an acid and a base.
  • They consist of positive ions (cations) and negative ions (anions).

Formation of Salts:

  • Neutralization Reaction: When an acid reacts with a base, it forms salt and water.
  • Reaction with Metals: Metals react with acids to form salts and hydrogen gas.
    • Example: Zn+H2SO4→ZnSO4+H2

Types of Salts:

  • Normal Salts: Formed when all the hydrogen ions in an acid are replaced by metal ions.
    • Example: Sodium chloride (NaCl)
  • Acid Salts: Formed when only part of the hydrogen ions in an acid are replaced by metal ions.
    • Example: Sodium bisulfate (NaHSO₄)
  • Basic Salts: Formed by the partial replacement of hydroxide ions in a base with an acid radical.
    • Example: Basic lead carbonate (Pb(OH)₂CO₃)

Properties of Salts:

  • Solubility: Most salts are soluble in water, but some, like barium sulfate (BaSO₄), are insoluble.
  • Electrical Conductivity: When dissolved in water, salts dissociate into ions, making the solution conductive.
  • Melting and Boiling Points: Salts generally have high melting and boiling points.

pH of Salt Solutions:

  • Neutral Salts: Formed from strong acids and strong bases; their solutions are neutral (pH = 7).
  • Acidic Salts: Formed from a strong acid and a weak base; their solutions are acidic (pH < 7).
  • Basic Salts: Formed from a weak acid and a strong base; their solutions are basic (pH > 7).

Common Uses of Salts:

  • Table Salt (NaCl): Used in cooking and food preservation.
  • Baking Soda (NaHCO₃): Used in baking as a leavening agent.
  • Epsom Salt (MgSO₄): Used in bath salts and as a laxative.
  • Bleaching Powder (Ca(OCl)₂): Used for disinfection and water purification.

Crystallization of Salts:

  • Salts can be crystallized from their aqueous solutions by evaporating the water, leading to the formation of solid crystals.

Environmental Impact:

  • Some salts can cause environmental issues, such as soil salinization, which affects agriculture and plant growth.

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