Question
What do you mean by a precipitation reaction? Explain giving an example.
✓
Answer
Any reaction in which an insoluble solid (called precipitate) is formed that separates from the solution is called a precipitation reaction.
Example: The reaction between barium chloride and sodium sulphate solution to form a white barium sulphate precipitate (alongwith sodium chloride solution) is an example of a precipitation reaction.
$\text{BaCl}_2(\text{aq})\ \ \ +\ \ \ \text{NaSO}_4(\text{aq})\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ }\ \text{BaSO}_4(\text{s})\ \ \ \ +\ \ \ 2\text{NaCl(aq)}\\ ^\text{Barium Chloride}\ \ \ \ \ \ \ ^\text{Sodium sulphate}\ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{Barium sulphate}\ \ \ \ \ \ \ \ ^\text{Sodium Chloride}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(White ppt.)}$
Example: The reaction between barium chloride and sodium sulphate solution to form a white barium sulphate precipitate (alongwith sodium chloride solution) is an example of a precipitation reaction.
$\text{BaCl}_2(\text{aq})\ \ \ +\ \ \ \text{NaSO}_4(\text{aq})\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ }\ \text{BaSO}_4(\text{s})\ \ \ \ +\ \ \ 2\text{NaCl(aq)}\\ ^\text{Barium Chloride}\ \ \ \ \ \ \ ^\text{Sodium sulphate}\ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{Barium sulphate}\ \ \ \ \ \ \ \ ^\text{Sodium Chloride}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(White ppt.)}$
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