Question

Define double displacement reaction and give one example of each of the following types of this reaction in which

(i) a yellow precipitate is formed.

Answer 1

1. Double displacement reaction

In a double displacement reaction, there occurs a replacement of the anions and cations of two compounds which further forms new products.

2. Example of a double displacement reaction where yellow precipitate is formed

An example of a double displacement reaction is given below.

The double displacement reaction between Lead nitrate $\left[\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\right]$ and Potassium iodide $\left(\mathrm{KI}\right)$ yields a yellow precipitate named Lead iodide $\left({\mathrm{PbI}}_2\right)$ along with Potassium nitrate $\left({\mathrm{KNO}}_3\right)$ as another product.

The chemical reaction is given below.

$$\begin{gathered} \mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+2\mathrm{KI}\left(\mathrm{aq}\right)\to {\mathrm{PbI}}_2\left(\mathrm{s}\right)+2{\mathrm{KNO}}_3\left(\mathrm{aq}\right) \\ \mathrm{Lead}\mathrm{nitrate}\mathrm{Potassium}\mathrm{Lead}\mathrm{Potassium} \\ \mathrm{iodide}\mathrm{iodide}\mathrm{nitrate} \end{gathered}$$