The molar solubilities of the following compounds (in mol/L) are:

AgBr = 7.3 x 10-7

AgCN = 7.7 x 10-9

AgSCN = 1.0 x 10-6

When these compounds are arranged in order of decreasing Ksp values, what is the correct order?

AgCN > AgSCN > AgBr
AgBr > AgCN > AgSCN
AgSCN > AgBr > AgCN
AgCN > AgBr > AgSCN

Respuesta :

Answer: The decreasing order of [tex]K_{sp}[/tex] is [tex]AgSCN>AgBr>AgCN[/tex]

Explanation:

  • For AgBr:

The balanced equilibrium reaction for the ionization of silver bromide follows:

[tex]AgBr\rightleftharpoons Ag^{+}+Br^-[/tex]

                 s      s

The expression for solubility constant for this reaction will be:

[tex]K_{sp}=[Ag^{+}][Br^-][/tex]

We are given:

[tex]s=7.3\times 10^{-7}mol/L[/tex]

Putting values in above equation, we get:

[tex]K_{sp}=s\times s\\\\K_{sp}=s^2\\\\K_{sp}=(7.3\times 10{-7})^2=5.33\times 10^{-13}[/tex]

Solubility product of AgBr = [tex]5.33\times 10^{-13}[/tex]

  • For AgCN:

The balanced equilibrium reaction for the ionization of silver cyanide follows:

[tex]AgCN\rightleftharpoons Ag^{+}+CN^-[/tex]

                    s      s

The expression for solubility constant for this reaction will be:

[tex]K_{sp}=[Ag^{+}][CN^-][/tex]

We are given:

[tex]s=7.7\times 10^{-9}mol/L[/tex]

Putting values in above equation, we get:

[tex]K_{sp}=s\times s\\\\K_{sp}=s^2\\\\K_{sp}=(7.7\times 10{-9})^2=5.93\times 10^{-17}[/tex]

Solubility product of AgCN = [tex]5.33\times 10^{-17}[/tex]

  • For AgSCN:

The balanced equilibrium reaction for the ionization of silver thiocyanate follows:

[tex]AgSCN\rightleftharpoons Ag^{+}+SCN^-[/tex]

                     s      s

The expression for solubility constant for this reaction will be:

[tex]K_{sp}=[Ag^{+}][SCN^-][/tex]

We are given:

[tex]s=1.0\times 10^{-6}mol/L[/tex]

Putting values in above equation, we get:

[tex]K_{sp}=s\times s\\\\K_{sp}=s^2\\\\K_{sp}=(1.0\times 10{-6})^2=1.0\times 10^{-12}[/tex]

Solubility product of AgSCN = [tex]1.0\times 10^{-12}[/tex]

The decreasing order of [tex]K_{sp}[/tex] follows:

[tex]AgSCN>AgBr>AgCN[/tex]