Q1. [3] medium thorough-understanding
Sodium chloride, potassium nitrate, copper sulphate and sodium acetate are all salts. What determines whether a salt solution is acidic, basic or neutral?
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
The nature of a salt solution (acidic, basic, or neutral) is determined by the relative strengths of the acid and base used to form it.
- Salts of a strong acid and strong base are neutral (pH = 7). Example: NaCl (HCl + NaOH).
- Salts of a strong acid and weak base are acidic (pH < 7). Example: copper sulphate (H₂SO₄ + Cu(OH)₂).
- Salts of a strong base and weak acid are basic (pH > 7). Example: sodium acetate (NaOH + CH₃COOH).
Potassium nitrate (strong acid + strong base) is neutral; sodium acetate (weak acid + strong base) is basic.
Source: Chapter 2, Section 2.4.2
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Explanation
- The key principle examiners expect: strength of parent acid and base determines the pH of the salt solution.
- Mention all three cases (neutral, acidic, basic) with the rule and at least one example each — this covers all 3 marks.
- Using examples from the question itself (copper sulphate, sodium acetate) shows application and earns full marks.
- Do not confuse "strong/weak" acid-base with "concentrated/dilute" — these are different concepts.