Generated by claude-sonnet-4-6 · 2026-06-14 10:30 · grounding rag
Model Answer
Observation: A bright yellow precipitate of lead iodide (PbI₂) is formed.
Type of reaction: Double displacement reaction (precipitation reaction).
Chemical equation:
$$2\text{KI}(aq) + \text{Pb(NO}_3)_2(aq) \rightarrow \text{PbI}_2(s)\downarrow + 2\text{KNO}_3(aq)$$
Source: Chapter 1, Chemical Reactions and Equations
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Explanation
- The examiner expects both observation (yellow precipitate) and reaction type for full marks.
- This is both a double displacement and a precipitation reaction — either term or both is acceptable, but mentioning precipitation strengthens the answer.
- The equation must be balanced and state symbols (aq, s) should be included; the ↓ symbol for precipitate is good practice.
- "Bright yellow precipitate" is the key observable fact — don't just write "precipitate forms."