Acids, Bases, Salts
SSC GD Self-Paced Course
Acids, bases, and salts are among the most important Chemistry topics asked in SSC GD, SSC CGL, CHSL, Railways, and state-level exams. This article covers definitions, properties, examples, reactions, uses, and common questions.
1. What Are Acids?
Acids are substances that produce hydrogen ions (H⁺) in water.
Simple Definition: Acids are sour substances that turn blue litmus paper red.
Taste: Sour
Ions produced: H⁺ ions
2. Types of Acids
Mineral (Inorganic) Acids
Examples:
- Hydrochloric acid (HCl)
- Sulphuric acid (H₂SO₄)
- Nitric acid (HNO₃)
Organic Acids
Examples:
- Acetic acid (vinegar)
- Citric acid (lemons)
- Lactic acid (curd)
3. Examples of Acids in Daily Life
- Lemon juice → Citric acid
- Vinegar → Acetic acid
- Curd → Lactic acid
- Ant sting → Formic acid
- Tamarind → Tartaric acid
- Apple → Malic acid
4. Properties of Acids
- Sour in taste
- Turn blue litmus red
- React with metals to produce hydrogen gas
- Conduct electricity in solution
- Corrosive in nature (especially mineral acids)
Example Reaction:
Zn + 2HCl → ZnCl₂ + H₂
(Zinc + Hydrochloric acid → Zinc chloride + Hydrogen gas)
5. What Are Bases?
Bases are substances that produce hydroxide ions (OH⁻) in water.
Simple Definition: Bases are bitter substances that turn red litmus paper blue.
Taste: Bitter
Touch: Slippery (soapy)
6. Types of Bases
Soluble bases → Alkalis
Examples:
- Sodium hydroxide (NaOH)
- Potassium hydroxide (KOH)
- Calcium hydroxide (lime water) Ca(OH)₂
Insoluble bases
Examples:
- Iron hydroxide
- Copper hydroxide
7. Examples of Bases in Daily Life
- Soap → Sodium or potassium salts
- Toothpaste → Mild bases
- Milk of magnesia → Magnesium hydroxide
- Lime water → Calcium hydroxide
- Bleaching powder → Contains Ca(OH)₂
8. Properties of Bases
- Bitter in taste
- Turn red litmus blue
- React with acids to form salt and water
- Caustic (burning) in nature
- Conduct electricity
9. What Are Salts?
A salt is formed when an acid reacts with a base.
Salt = Acid + Base Reaction
This reaction is called Neutralization.
Example:
HCl + NaOH → NaCl + H₂O
(Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water)
10. Types of Salts
Normal Salt
- Formed by complete neutralization
- Example: NaCl, KCl
Acidic Salt
- Formed when base is not fully replaced
- Example: NaHSO₄
Basic Salt
- Formed when acid is not fully replaced
- Example: MgClOH
Double Salt
- Contains more than one basic or acidic radical
- Example: Alum
(SSC GD usually asks Normal and Common Salts)
11. Examples of Common Salts
- Table salt → Sodium chloride (NaCl)
- Baking soda → Sodium bicarbonate (NaHCO₃)
- Washing soda → Sodium carbonate (Na₂CO₃·10H₂O)
- Bleaching powder → CaOCl₂
- Gypsum → CaSO₄·2H₂O
- Plaster of Paris → CaSO₄·0.5H₂O
12. Important Chemical Compounds Asked in SSC GD
Baking Soda
NaHCO₃
Used in cooking, antacid
Washing Soda
Na₂CO₃·10H₂O
Used in washing clothes, softening water
Bleaching Powder
CaOCl₂
Used in disinfecting water
Vinegar
CH₃COOH (Acetic acid)
Lime Water
Ca(OH)₂
Turns milky with CO₂
Plaster of Paris (POP)
CaSO₄·0.5H₂O
Used for casts, statues
13. Indicators
Indicators show whether a substance is acid or base.
Natural Indicators:
- Litmus (from lichens)
- Red cabbage juice
- Turmeric
Chemical Indicators:
- Phenolphthalein
- Methyl orange
Litmus
- Acid → red
- Base → blue
Turmeric
- Acid → yellow
- Base → red or brown
Phenolphthalein
- Acid → colorless
- Base → pink
14. pH Scale
pH measures the acidity or basicity of a solution.
Range: 0 to 14
pH < 7 → Acid
pH = 7 → Neutral
pH > 7 → Base
Examples:
- Lemon juice → pH 2
- Milk → pH 6.5
- Water → pH 7
- Soap → pH 10
15. Neutralization Reaction
Acid + Base → Salt + Water
Examples:
HCl + NaOH → NaCl + H₂O
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
Applications:
- Treatment of ant bites (use base)
- Acid indigestion (use antacid)
- Soil treatment in agriculture
16. Hard and Soft Water
Hard Water
- Contains calcium and magnesium salts
- Forms less lather with soap
Soft Water
- Contains no calcium or magnesium
- Forms lather easily
Hardness Removal:
- Boiling
- Adding washing soda
- Ion exchange method
17. Important Chemistry Questions for SSC GD
- Acid turns blue litmus → red
- Base turns red litmus → blue
- Baking soda formula → NaHCO₃
- Washing soda formula → Na₂CO₃·10H₂O
- Bleaching powder → CaOCl₂
- POP → CaSO₄·0.5H₂O
- Gypsum → CaSO₄·2H₂O
- Ant bite contains → Formic acid
- Vinegar contains → Acetic acid
- Neutralization → Acid + base reaction
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