Select the correct answer.

Which chemical equation represents a precipitation reaction?

A. [tex][tex]$MgBr_2 + 2 HCl \rightarrow MgCl_2 + 2 HBr$[/tex][/tex]
B. [tex][tex]$K_2CO_3 + PbCl_2 \rightarrow 2 KCl + PbCO_3$[/tex][/tex]
C. [tex][tex]$4 LiC_2H_3O_2 + TiBr_4 \rightarrow 4 LiBr + Ti(C_2H_3O_2)_4$[/tex][/tex]
D. [tex][tex]$2 NH_4NO_3 + CuCl_2 \rightarrow 2 NH_4Cl + Cu(NO_3)_2$[/tex][/tex]



Answer :

To determine which chemical equation represents a precipitation reaction, we need to examine each option and identify if any of the products form an insoluble solid (precipitate) in water.

A. [tex]\( MgBr_2 + 2 HCl \rightarrow MgCl_2 + 2 HBr \)[/tex]

This reaction involves magnesium bromide reacting with hydrochloric acid to produce magnesium chloride and hydrogen bromide. All of these compounds are soluble in water, so no precipitate forms in this reaction.

B. [tex]\( K_2CO_3 + PbCl_2 \rightarrow 2 KCl + PbCO_3 \)[/tex]

This reaction involves potassium carbonate reacting with lead(II) chloride. The products are potassium chloride and lead(II) carbonate. Potassium chloride is soluble in water, but lead(II) carbonate ([tex]\(PbCO_3\)[/tex]) is insoluble in water, which means it forms a precipitate.

C. [tex]\( 4 LiC_2H_3O_2 + TiBr_4 \rightarrow 4 LiBr + Ti(C_2H_3O_2)_4 \)[/tex]

This reaction involves lithium acetate reacting with titanium bromide to produce lithium bromide and titanium acetate. All these products are soluble in water, so no precipitate forms in this reaction.

D. [tex]\( 2 NH_4NO_3 + CuCl_2 \rightarrow 2 NH_4Cl + Cu(NO_3)_2 \)[/tex]

This reaction involves ammonium nitrate reacting with copper(II) chloride to produce ammonium chloride and copper(II) nitrate. All of these compounds are soluble in water, so no precipitate forms in this reaction.

Conclusion:
The only reaction that forms an insoluble product (precipitate) is:

B. [tex]\( K_2CO_3 + PbCl_2 \rightarrow 2 KCl + PbCO_3 \)[/tex]

So, the correct answer is:

B. [tex]\( K_2CO_3 + PbCl_2 \rightarrow 2 KCl + PbCO_3 \)[/tex]