AAgNO(aq)+ sodiumchloride
NaCl(aq)→ silverchloride(ppt.)
AgCl(s)↓+ sodiumnitrateNaNO3 (aq)
​

Understanding Double Displacement Reactions
Double displacement reactions, also known as double replacement reactions, involve the exchange of ions between two compounds. A classic example of this type of reaction is when two ionic compounds react to form two new compounds.
Precipitation Reactions
Precipitation reactions occur when two soluble salts react in solution to form an insoluble product, known as a precipitate. This is a common occurrence in double displacement reactions.
Example of a Precipitation Reaction
An illustrative example is the reaction between silver nitrate (AgNO3) and sodium chloride (NaCl):
- Reactants: AgNO3 + NaCl
- Products: AgCl (precipitate) + NaNO3
In this reaction, the silver (Ag+) ions from silver nitrate and the chloride (Cl-) ions from sodium chloride combine to form silver chloride (AgCl), which is insoluble in water and precipitates out of the solution.
Key Points
- Formation of Precipitate: The formation of AgCl is a direct result of the double displacement reaction.
- Visual Observation: You can observe the white precipitate of AgCl forming when the two clear solutions are mixed.
- Solubility Rules: Understanding solubility rules helps predict whether a precipitate will form. For instance, most chlorides are soluble, except for those of silver, lead, and mercury.
Conclusion
In summary, the reaction between silver nitrate and sodium chloride exemplifies a precipitation reaction that also represents a double displacement reaction. The formation of an insoluble precipitate is a key characteristic that makes these reactions significant in analytical chemistry and various applications.