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Question
When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution.
- What do you think substance X is likely to be?
- Name the substance which the yellow solid consists of.
- Which characteristic of chemical reactions is illustrated by this example?
- Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.
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Solution
- Substance X is likely to be lead nitrate (Pb(NO3)2), because on reacting with potassium iodide, it forms a yellow precipitate.
- The yellow solid or precipitate consists of lead iodide (PbI2), which is one of the products in this reaction.
- This chemical reaction is characterised by the formation of a precipitate.
- \[\ce{2KI_{(aq)} + Pb(NO3)2_{(aq)} -> PbI2_{(s)} + 2KNO3_{(aq)}}\]
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