Class 10 Science MCQ Test – Acids, Bases and Salts (Chapter 2) | Full Chapter Test
Class 10 Science – Chapter 2: Acids, Bases and Salts (Detailed Notes)
These notes cover complete theory, reactions, formulas, practical concepts, and exam-oriented points for CBSE & GSEB students.
1. Acids and Bases – Basic Concepts
Acids
Substances which produce \( H^+ \) ions in aqueous solution.
Examples: HCl, H₂SO₄, HNO₃
Bases
Substances which produce \( OH^- \) ions in aqueous solution.
Examples: NaOH, KOH, Ca(OH)₂
Alkali
Bases which are soluble in water.
2. Properties of Acids and Bases
Acids
- Sour taste
- Turn blue litmus red
- React with metals to produce hydrogen gas
- Conduct electricity (in aqueous solution)
Base/Alkali
- Bitter taste
- Turn red litmus blue
- Soapy touch
- Conduct electricity
3. Chemical Reactions of Acids
1. With Metals
\( Zn + 2HCl \rightarrow ZnCl_2 + H_2 \uparrow \)
2. With Metal Carbonates
\( Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2 \)
3. With Metal Bicarbonates
\( NaHCO_3 + HCl \rightarrow NaCl + H_2O + CO_2 \)
Test for CO₂ Gas
\( CO_2 + Ca(OH)_2 \rightarrow CaCO_3 \downarrow + H_2O \)
4. Chemical Reactions of Bases
With Acids (Neutralisation)
\( NaOH + HCl \rightarrow NaCl + H_2O \)
With Non-Metal Oxides
\( Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O \)
5. Strength of Acids and Bases
Strength depends on degree of ionisation.
- Strong Acids: HCl, HNO₃
- Weak Acids: CH₃COOH
- Strong Bases: NaOH, KOH
- Weak Bases: NH₄OH
6. pH Scale
Used to measure acidity/basicity of solution.
pH scale: 0 → 14
- pH < 7 → Acidic
- pH = 7 → Neutral
- pH > 7 → Basic
Lower pH → stronger acid
Importance of pH
- Digestion (HCl in stomach)
- Tooth decay (pH < 5.5)
- pH of soil for crops
- pH of water bodies
7. Salts
Salts are formed from neutralisation reaction.
Types:
- Neutral salt → NaCl
- Acidic salt → NH₄Cl
- Basic salt → Na₂CO₃
8. Hydrolysis of Salts
Salts react with water to produce acidic/basic solution.
- Strong acid + weak base → acidic salt
- Weak acid + strong base → basic salt
9. Common Chemicals from Salts
1. Bleaching Powder
\( Ca(OH)_2 + Cl_2 \rightarrow CaOCl_2 + H_2O \)
- Used for bleaching and disinfectant
2. Baking Soda
\( NaCl + NH_3 + H_2O + CO_2 \rightarrow NaHCO_3 \downarrow + NH_4Cl \)
On heating:
\( 2NaHCO_3 \rightarrow Na_2CO_3 + H_2O + CO_2 \)
3. Washing Soda
\( Na_2CO_3 \cdot 10H_2O \)
- Used in cleaning and softening water
4. Plaster of Paris (POP)
\( CaSO_4 \cdot \frac{1}{2}H_2O \)
Preparation:
\( CaSO_4 \cdot 2H_2O \xrightarrow{100-120^\circ C} CaSO_4 \cdot \frac{1}{2}H_2O \)
With water:
\( CaSO_4 \cdot \frac{1}{2}H_2O + H_2O \rightarrow CaSO_4 \cdot 2H_2O \)
10. Water of Crystallisation
Fixed number of water molecules in a salt.
Example: \( CuSO_4 \cdot 5H_2O \)
11. Important Exam Points
- Acids show properties only in aqueous solution
- pH scale is logarithmic
- Remember all common chemical reactions
- POP and Washing soda questions are frequently asked
- Gas test reactions are important
⬇️ Attempt the test given below after revising these notes
Class 10 Science
Chapter 2: Acids, Bases and Salts | Full Chapter Test
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