Question

What type of reaction occurs when you mix the KI (aq) and Pb(NO_3)_2_{(aq)} reactant solutions?

A) Synthesis
B) Decomposition
C) Double displacement
D) Combustion

Answer 1

A double displacement reaction occurs when potassium iodide and lead(II) nitrate are mixed, forming a yellow precipitate of lead(II) iodide and soluble potassium nitrate.

Step-by-step explanation:

When potassium iodide (KI) is mixed with lead(II) nitrate (Pb(NO3)2) in aqueous solution, a double displacement reaction occurs. This reaction involves the exchange of ions between the two compounds, forming lead(II) iodide (PbI2), a brilliant yellow precipitate, and soluble potassium nitrate (KNO3).

The reaction is as follows: 2KI (aq) + Pb(NO3)2 (aq) → 2KNO3 (aq) + PbI2 (s). This process is a classic example of a precipitation reaction, where the insoluble product, lead iodide, precipitates out of the solution.