Predict whether or not a precipitate forms upon mixing 175.0 mLmL of a 0.0055 MKClMKCl solution with 145.0 mLmL of a 0.0015 MM AgNO3AgNO3 solution. Identify the precipitate, if any.

Respuesta :

Answer : The precipitate is, AgCl.

Explanation :

The balanced chemical reaction will be:

[tex]AgNO_3(aq)+KCl(aq)\rightarrow AgCl(s)+KNO_3(aq)[/tex]

First we have to calculate the molarity of [tex]Cl^-[/tex] ion.

[tex]M_1V_1=M_2V_2[/tex]

where,

[tex]M_1\text{ and }V_1[/tex] are the initial molarity and volume of KCl.

[tex]M_2\text{ and }V_2[/tex] are the final molarity and volume of [tex]Cl^-[/tex] ion.

We are given:

[tex]M_1=0.0055M\\V_1=175.0mL\\M_2=?\\V_2=175.0+145.0=320mL[/tex]

Putting values in above equation, we get:

[tex]0.0055M\times 175.0mL=M_2\times 320mL\\\\M_2=0.00301M[/tex]

Now we have to calculate the molarity of [tex]Ag^+[/tex] ion.

[tex]M_1V_1=M_2V_2[/tex]

where,

[tex]M_1\text{ and }V_1[/tex] are the initial molarity and volume of [tex]AgNO_3[/tex].

[tex]M_2\text{ and }V_2[/tex] are the final molarity and volume of [tex]Ag^+[/tex] ion.

We are given:

[tex]M_1=0.0015M\\V_1=145.0mL\\M_2=?\\V_2=175.0+145.0=320mL[/tex]

Putting values in above equation, we get:

[tex]0.0015M\times 145.0mL=M_2\times 320mL\\\\M_2=0.000679M[/tex]

Now we have to calculate the value of reaction quotient.

The expression for reaction quotient will be :

[tex]Q_{sp}=[Ag^+][Cl^-][/tex]

Now put all the given values in this expression, we get

[tex]Q_{sp}=(0.000679)\times (0.00301)=2.04\times 10^{-6}[/tex]

The given solubility constant value is, [tex]K_{sp}=1.77\times 10^{-10}[/tex]

  • When [tex]K_{sp}>Q_{sp}[/tex]; the reaction is product favored.  (No precipitation)
  • When [tex]K_{sp}<Q_{sp}[/tex]; the reaction is reactant favored.  (Precipitation)
  • When [tex]K_{sp}=Q_{sp}[/tex]; the reaction is in equilibrium. (Sparingly soluble)

As, [tex]K_{sp}<Q_{sp}[/tex] then the reaction is reactant favored that means formation of precipitation.

Thus, the precipitate is, AgCl.