State any three general physical properties of ionic compounds. Explain why ionic compounds dissolve readily in water but not in non-polar solvents such as petrol or kerosene.
Generated by claude-sonnet-4-6 · 2026-06-26 01:05 · grounding rag
Model Answer
Three general physical properties of ionic compounds:
- They have high melting and boiling points due to strong electrostatic forces between ions.
- They conduct electricity in molten state or when dissolved in water (due to free ions).
- They are generally hard and brittle solids at room temperature.
Why ionic compounds dissolve in water but not in non-polar solvents:
Water is a polar solvent. Its polar molecules interact with the positive and negative ions of ionic compounds, overcoming the ionic bonds and dissolving them. Non-polar solvents like petrol or kerosene cannot interact with ions in this way, so ionic compounds do not dissolve in them. The principle is "like dissolves like" — polar solvents dissolve ionic/polar compounds; non-polar solvents dissolve non-polar compounds.
Source: Chapter 3, Ionic Compounds; Chapter 4, Section 4.1
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Explanation
- The textbook (Ch. 3 summary) directly states ionic compounds have high melting/boiling points and conduct electricity — use these confidently.
- The third property (hard and brittle) is standard CBSE content for ionic compounds from Ch. 3.
- For the dissolution part, the examiner expects the "like dissolves like" principle and the idea that polar water stabilises ions, while non-polar solvents cannot. This is a conceptual explanation, so 2–3 clear lines are enough — don't over-explain.
- Avoid copying carbon compound properties (low MP/BP, non-conductors) — those belong to covalent compounds.