To determine which chemical equation represents a precipitation reaction, we need to identify the reaction that produces a solid (precipitate) in its products.
Let's examine each reaction in detail:
Option A:
[tex]\[ Mg \left( ClO _3\right)_2(a q)+2 HCl ( aq ) \rightarrow MgCl _2(aq)+2 HClO _3(aq) \][/tex]
- In this reaction, all products remain aqueous (aq) meaning they stay dissolved in water.
- No solid precipitate is formed, so this is not a precipitation reaction.
Option B:
[tex]\[ \operatorname{AlBr}_3(a q)+3 Lil (a q) \rightarrow \operatorname{AlI}_3(a q)+3 LiBr (a q) \][/tex]
- Similar to Option A, all products are in aqueous form, indicating they stay dissolved in water.
- No solid precipitate is formed here either, so this is not a precipitation reaction.
Option C:
[tex]\[ NH _4 NO _3(a q)+ HBr ( aq ) \rightarrow NH _4 Br ( aq )+ HNO _3( aq ) \][/tex]
- In this reaction, all products are aqueous.
- Since no solid is formed, this cannot be considered a precipitation reaction.
Option D:
[tex]\[ Li _2 CO _3(a q)+ FeCl _2(a q) \rightarrow 2 LiCl (a q)+ FeCO _3(s) \][/tex]
- In this reaction, the product [tex]\( FeCO _3 \)[/tex] is a solid (s), referred to as iron(II) carbonate.
- The formation of [tex]\( FeCO _3(s) \)[/tex] means that a precipitate forms in this reaction.
Therefore, the reaction that represents a precipitation reaction is:
[tex]\[ \boxed{Li _2 CO _3(a q)+ FeCl _2(a q) \rightarrow 2 LiCl (a q)+ FeCO _3(s)} \][/tex]
Thus, the correct answer is Option D.
