Question

Identify the double displacement reaction which does not involve a precipitate formation.

• A. $BaC{l}_2\left(aq\right)+N{a}_{2}S{O}_4\left(aq\right)\to BaS{O}_4\left(s\right)+NaCl\left(aq\right)$
• B. $Pb\left(N{O}_3{)}_2\right(aq)+2KI(aq)\to Pb{I}_2(s)+2KN{O}_3(aq)$
• C. $HN{O}_3\left(aq\right)+KOH\left(aq\right)\to KN{O}_3\left(aq\right)+H_{2}O\left(l\right)$
• D. $AgN{O}_3\left(aq\right)+NaCl\left(aq\right)\to AgCl\left(s\right)+NaN{O}_3\left(aq\right)$

Answer 1

The correct option is C $HN{O}_3\left(aq\right)+KOH\left(aq\right)\to KN{O}_3\left(aq\right)+H_{2}O\left(l\right)$

A double displacement reaction is a type of reaction in which two reactants exchange ions to form two new compounds. Although most of the double displacement reactions result in precipitate formation but not all of them.

For example, reactions that involve neutralisation undergoes ion exchange between the two reactants but result in the formation of a salt, which mostly is not a precipitate.

So, among the given reactions, only the neutralisation reaction below that does not involve a precipitate formation is:

$HN{O}_3\left(aq\right)+KOH\left(aq\right)\to KN{O}_3\left(aq\right)+H_{2}O\left(l\right)$

However, in the other reactions, $BaS{O}_4$, $Pb{I}_2$ and $AgCl$ are all insoluble precipitaes formed during the reaction.