Salts & Neutralisation
World B — Acids, Bases & Solutions
17.A — NEUTRALISATION & SALT TYPES
H⁺
+
OH⁻
→
+
H₂O
R17.01 Neutralisation Reaction
- Acid + Base → Salt + Water.
- H⁺ ions combine with OH⁻ ions.
- Highly exothermic process.
+
-
+
-
+
-
+
-
+
R17.02 What is a Salt?
- Ionic compound formed by neutralisation.
- Cation from Base + Anion from Acid.
- Electrically neutral crystal lattice.
R17.03 Types of Salts
- Neutral (Strong Acid + Strong Base).
- Acidic (Strong Acid + Weak Base).
- Basic (Weak Acid + Strong Base).
R17.04 Families of Salts
- Grouped by common positive/negative ions.
- Chlorides (from HCl).
- Sulfates (from H₂SO₄), Nitrates (from HNO₃).
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H₂O
R17.05 Water of Crystallization
- Fixed H₂O molecules in crystal structure.
- Hydrated salts (e.g., Blue CuSO₄·5H₂O).
- Heating removes water, leaving anhydrous salt (White).
vs
R17.06 Efflorescence & Deliquescence
- Efflorescence: Losing water to dry air.
- Deliquescence: Absorbing water until dissolved.
- Hygroscopic: Absorbs water but stays solid.
17.B — COMMERCIALLY IMPORTANT SALTS
R17.07 Sodium Chloride (NaCl)
- Common Salt / Table Salt.
- Formed by seawater evaporation or rock salt mining.
- Raw material for many other chemicals.
Cl₂
H₂
NaOH
R17.08 Chlor-Alkali Process
- Electrolysis of Brine (NaCl solution).
- Products: Chlorine gas (Anode), Hydrogen (Cathode).
- Yields Sodium Hydroxide (NaOH - Caustic Soda).
Cl₂
R17.09 Bleaching Powder (CaOCl₂)
- Slaked lime + Chlorine gas.
- Yellowish-white powder with strong Cl₂ smell.
- Used for disinfecting water and bleaching cotton.
R17.10 Baking Soda (NaHCO₃)
- Sodium Hydrogen Carbonate.
- Mild, non-corrosive basic salt.
- Heating releases CO₂, making dough rise.
- Used in antacids and fire extinguishers.
R17.11 Washing Soda (Na₂CO₃·10H₂O)
- Sodium Carbonate Decahydrate.
- Basic salt containing 10 molecules of water.
- Used for removing permanent hardness of water.
R17.12 Plaster of Paris
- CaSO₄·½H₂O (Calcium Sulfate Hemihydrate).
- Made by heating Gypsum to exactly 373K.
- Adding water sets it back into hard solid Gypsum.
- Used for bone casts and sculpting.