Practice Questions
🔢 Practice Numerical
Solution:
- HCl + NaOH → NaCl + H₂O
- Moles of HCl = 36.5/36.5 = 1 mole
- 1 mole HCl needs 1 mole NaOH
- Mass of NaOH = 1 × 40 = 40g
→ Use balanced equation and molar masses for neutralization calculations
Solution:
- CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
- Moles of CaCO₃ = 10/100 = 0.1 mole
- 1 mole CaCO₃ produces 1 mole CO₂
- Mass of CO₂ = 0.1 × 44 = 4.4g
→ Use stoichiometry to find product mass from reactant mass
Solution:
- HCl + NaOH → NaCl + H₂O
- Moles of NaOH = 0.1 × 0.025 = 0.0025 moles
- 1 mole NaOH needs 1 mole HCl
- Volume of HCl = 0.0025/0.1 = 0.025L = 25ml
→ For neutralization, moles of acid = moles of base (for 1:1 reactions)
🎯 Application-Based Questions
Answer: Ant bite injects formic acid (HCOOH) into our skin. This acid causes the burning sensation. Rubbing baking soda (mild base) neutralizes the acid and provides relief.
Answer: Food particles, especially sugary foods, are converted to acids by bacteria in mouth. These acids attack tooth enamel (calcium phosphate). Brushing with toothpaste (mild base) neutralizes these acids and prevents tooth decay.
Answer: He should add lime [Ca(OH)₂] or limestone (CaCO₃) to the soil. These are basic in nature and will neutralize the excess acid in soil, making it suitable for plant growth.
Answer: Pickles contain acids (acetic acid, citric acid) which can react with metals to form salts and hydrogen gas. This would corrode the metal container and spoil the pickle. Glass is inert and doesn’t react with acids
Answer: Stomach produces HCl for digestion. Excess acid causes acidity. Antacids contain mild bases like Mg(OH)₂ or Al(OH)₃ which neutralize excess stomach acid: HCl + Mg (OH)₂ → MgCl₂ + H₂O, providing relief.