42. NCERT Exemplar XV

 

$Pb(NO_3​)_2$​(aq) + $2KI$(aq) → $PbI_2$​(s) + $2KNO_3$​(aq)$PbI_2$​(s) + $2KNO_3$​(g)$PbI_2$​(l) + $2KNO_3$​(s)$PbI_2$​(aq) + $2KNO_3$​(aq)

 

This is an example of exothermicendothermicprecipitationdecomposition and a double displacement reaction.

 

In the above reaction, solid lead iodide ($PbI_2$​) precipitates are formed. Hence, $x$ represents the solid(s) form of lead iodide, and $y$ represents potassium nitrate's aqueous (aq) form.

 

 

$2FeSO_4$​(s) $\xrightarrow[]{Heat}$ $Fe_2​O_3$​(s) + $SO_4$​(g) + $SO_3$​(g)$Fe_2​O_3$​(s) + $SO_3$​(g) + $SO_4$​(g)$Fe_2​O_3$​(s) + $SO_2$​(g) + $SO_3$​(g)$Fe_2​O_4$​(s) + $SO_2$​(g) + $SO_3$​(g)

The decomposition of ferrous sulphate is an exothermicendothermicdecompositionprecipitation reaction because it includes heat absorption to generate ferric oxide ($Fe_2​O_3$), sulphur dioxide ($SO_2$), and sulphur trioxide ($SO_3$).