Acids, Bases and Salts
Short Questions
1. What is an acid according to Arrhenius theory?
- An acid produces H⁺ ions in water.
2. What is a base according to Arrhenius theory?
- A base produces OH⁻ ions in water.
3. What turns red litmus paper blue?
- A base or alkali.
4. What is the pH of a neutral solution?
- 7
5. What is a strong acid?
- An acid that dissociates completely in water, e.g., HCl.
6. What is a weak base?
- A base that partially dissociates in water, e.g., NH₃.
7. What is the formula for sodium chloride?
- NaCl
8. What gas is released when a metal reacts with an acid?
- Hydrogen (H₂).
9. What is the chemical formula of blue vitriol?
- CuSO₄·5H₂O
10. What is water of crystallization?
- Water molecules included in the crystal structure of a compound.
11. What is the pH range for an acidic solution?
- Less than 7.
12. What is a universal indicator?
- A mixture of dyes showing different colors at different pH values.
13. What is formed in a neutralization reaction?
- A salt and water.
14. What is the molarity of a solution?
- Moles of solute per liter of solution (mol/L).
15. What type of oxide is CO₂?
- Acidic oxide.
16. What is an amphoteric oxide?
- An oxide that reacts with both acids and bases, e.g., ZnO.
17. What gas turns lime water milky?
- Carbon dioxide (CO₂).
18. What is the basicity of H₂SO₄?
- 2 (dibasic).
19. What conducts electricity in an aqueous solution?
- Ions.
20. What is electrolysis?
- Decomposition of a compound by electric current.
Long Questions
1. How does litmus paper help detect acids and bases?
- Litmus paper is an indicator that changes color in acidic or basic solutions. Red litmus turns blue in bases, and blue litmus turns red in acids, helping identify them easily.
2. What happens when an acid reacts with a metal? Give an example.
- When an acid reacts with a metal, it produces a salt and hydrogen gas. For example, Mg + 2HCl → MgCl₂ + H₂, where magnesium reacts with hydrochloric acid.
3. Explain the neutralization reaction with an example.
- A neutralization reaction occurs when an acid reacts with a base to form a salt and water. For instance, HCl + NaOH → NaCl + H₂O, producing sodium chloride and water.
4. What is the difference between a strong acid and a weak acid?
- A strong acid dissociates completely in water, producing many H⁺ ions, like HCl. A weak acid partially dissociates, producing fewer H⁺ ions, like CH₃COOH (acetic acid).
5. How does a universal indicator work to measure pH?
- A universal indicator shows different colors at different pH levels, indicating the acidity or basicity of a solution. By comparing the color to a pH chart, the pH value is determined.
6. What is water of crystallization? Give an example.
- Water of crystallization is water molecules included in the crystal structure of certain compounds. For example, CuSO₄·5H₂O (blue vitriol) contains five water molecules per formula unit.
7. Why do some salts conduct electricity in aqueous solutions?
- Salts dissociate into ions in water, and these ions move to carry electric current. For example, NaCl in water forms Na⁺ and Cl⁻ ions, which conduct electricity.
8. What happens during the electrolysis of water?
- Electrolysis of water breaks it into hydrogen and oxygen gases using electric current. At the cathode, 2H₂O + 2e⁻ → H₂ + 2OH⁻, and at the anode, 2H₂O → O₂ + 4H⁺ + 4e⁻.
9. How are metal oxides different from non-metal oxides?
- Metal oxides, like CaO, are basic and react with acids to form salts and water. Non-metal oxides, like CO₂, are acidic and react with bases to form salts and water.
10. What is the significance of pH in everyday life?
- pH determines the suitability of solutions for processes like soil fertility or digestion. For example, blood needs a pH around 7.4, and soil pH affects plant growth.
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