Question

Identify the precipitate (if any) that forms when Na2S and CdSO4 are mixed.

Answer 1

Answer : Cadmium sulfide (CdS) precipitate is formed.

Explanation :

When the sodium sulfide, $(Na_2S)$ is mixed with cadmium sulfate, $(CdSO_4)$ then cadmium sulfide precipitate and sodium sulfate, $(Na_2SO_4)$ is formed. The cadmium sulfide is insoluble in hot and cold water but sodium sulfate is soluble in water.

The balanced chemical reaction will be,

$Na_2S+CdSO_4\rightarrow Na_2SO_4+CdS$

This reaction is an example of double displacement reaction in which the cation and anion of the two reactants exchange their places to give two new products.

This is a chemical reaction where the two clear solutions mixed to produce a bright yellow colored precipitate of cadmium sulfide.

Answer 2

The precipitate that is formed when ${\text{N}}{{\text{a}}_2}{\text{S}}$ reacts with ${\text{CdS}}{{\text{O}}_4}$  is  $\boxed{{\text{CdS}}}$

The given reaction occurs as follows:

 ${\text{N}}{{\text{a}}_2}{\text{S}}+{\text{CdS}}{{\text{O}}_4}\to{\text{N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}\left( {aq}\right)+{\text{CdS}}\left( s \right)$

Further Explanation:

Precipitation reaction:

It is the type of reaction in which an insoluble salt is formed by the combination of two solutions containing soluble salts. That insoluble salt is known as precipitate, and therefore such reactions are named precipitation reactions. An example of precipitation reaction is,

${\text{AgN}}{{\text{O}}_3}\left({aq}\right)+{\text{KBr}}\left({aq}\right)\to {\text{AgBr}}\left(s\right)+{\text{KN}}{{\text{O}}_3}\left({aq}\right)$

Here, AgBr is a precipitate.

The solubility rules to determine the solubility of the compound are as follows:

1. The common compounds of group 1A are soluble.

2. All the common compounds of ammonium ion and all acetates, chlorides, nitrates, bromides, iodides, and perchlorates are soluble in nature. Only the chlorides, bromides, and iodides of ${\text{A}}{{\text{g}}^ + }$ , ${\text{P}}{{\text{b}}^{2 + }}$ , ${\text{C}}{{\text{u}}^ + }$ and ${\text{Hg}}_2^{2 + }$ are not soluble.

3. All common fluorides, except for ${\text{Pb}}{{\text{F}}_{\text{2}}}$ and group 2A fluorides, are soluble. Moreover, sulfates except ${\text{CaS}}{{\text{O}}_{\text{4}}}$ , ${\text{SrS}}{{\text{O}}_{\text{4}}}$ , ${\text{BaS}}{{\text{O}}_{\text{4}}}$ , ${\text{A}}{{\text{g}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}$ and ${\text{PbS}}{{\text{O}}_{\text{4}}}$  are soluble.

4. All common metal hydroxides except ${\text{Ca}}{\left({{\text{OH}}}\right)_{\text{2}}}$ , ${\text{Sr}}{\left( {{\text{OH}}}\right)_{\text{2}}}$ , ${\text{Ba}}{\left( {{\text{OH}}}\right)_{\text{2}}}$ and hydroxides of group 1A and that of transition metals are insoluble in nature.

5. All carbonates and phosphates, except those formed by group 1A and ammonium ion, are insoluble.

6. All sulfides, except those formed by group 1A, 2A, and ammonium ion are insoluble.

7. Salts that contain ${\text{C}}{{\text{l}}^ - }$ , ${\text{B}}{{\text{r}}^ - }$ or ${{\text{I}}^ - }$ are usually soluble except for the halide salts of ${\text{A}}{{\text{g}}^ + }$ , ${\text{P}}{{\text{b}}^{2 + }}$ and ${\left({{\text{H}}{{\text{g}}_2}}\right)^{{\text{2 + }}}}$ .

8. The chlorides, bromides, and iodides of all the metals are soluble in water, except for silver, lead, and mercury (II). Mercury (II) iodide is water insoluble. Lead halides are soluble in hot water.

9. The perchlorates of group 1A and group 2A are soluble in nature.

10. All sulfates of metals are soluble, except for lead, mercury (I), barium, and calcium sulfates.

The given reaction occurs as follows:

 ${\text{N}}{{\text{a}}_2}{\text{S}}+{\text{CdS}}{{\text{O}}_4}\to{\text{N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}+{\text{CdS}}$

This is an example of a double displacement reaction in which two ionic compounds are exchanged with each other and two new compounds are formed. ${\text{N}}{{\text{a}}_2}{\text{S}}{{\text{O}}_4}$  is a soluble salt according to the solubility rules. So CdS will form precipitate in this reaction.

Learn more:

1. Balanced chemical equation: brainly.com/question/1405182

2. The net ionic equation for the reaction of ${\text{MgS}}{{\text{O}}_{\text{4}}}$ with ${\text{Sr}}{\left({{\text{N}}{{\text{O}}_3}}\right)_2}$ : brainly.com/question/4357519

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Chemical reaction and equation

Keywords: precipitation reaction, precipitate, insoluble, soluble, CdS, Na2SO4, Na2S, CdSO4, double displacement, salt, solubility rules.