What do you mean by a precipitation reaction? Explain by giving examples.
A precipitation reaction is a type of chemical reaction that produces an insoluble salt as one of the products. These reactions involve an exchange of ions between the reactants, making them a type of double displacement reaction.
For example, when sodium sulphate solution reacts with barium chloride solution, a white precipitate of barium sulphate (BaSO₄) is formed. The Ba²⁺ ions and SO₄²⁻ ions combine to form the insoluble BaSO₄, while sodium chloride remains dissolved in the solution.
Another example is the reaction between lead(II) nitrate and potassium iodide solutions, which also produces a precipitate. In such reactions, the insoluble product separates out as a solid from the solution.
Explanation
The textbook defines precipitation reactions as those producing insoluble salts. The context provides the BaSO₄ example from the double displacement reaction discussion, where ions are exchanged between reactants. The lead(II) nitrate and potassium iodide reaction is also referenced as another example of precipitation.