A generic salt, AB 2 , has a molar mass of 345 g/mol and a solubility of 8.70 g/L at 25 °C. AB 2 (s) − ⇀ ↽ − A 2 + (aq) + 2B − (aq) What is the K sp of this salt at 25 °C

Respuesta :

Answer : The value of [tex]K_{sp}[/tex] of the generic salt is, [tex]1.60\times 10^{-5}[/tex]

Explanation :

As we are given that, a solubility of salt  is, 8.70 g/L that means 8.70 grams of salt present in 1 L of solution.

First we have to calculate the moles of salt [tex](AB_2)[/tex]

[tex]\text{Moles of }AB_2=\frac{\text{Mass of }AB_2}{\text{Molar mass of }AB_2}[/tex]

Molar mass of [tex]AB_2[/tex] = 345 g/mol

[tex]\text{Moles of }AB_2=\frac{8.70g}{345g/mol}=0.0252mol[/tex]

Now we have to calculate the concentration of [tex]A^{2+}\text{ and }B^-[/tex]

The equilibrium chemical reaction will be:

[tex]AB_2(s)\rightleftharpoons A^{2+}(aq)+2B^-(aq)[/tex]

Concentration of [tex]A^{2+}[/tex] = [tex]\frac{0.0252mol}{1L}=0.0252M[/tex]

Concentration of [tex]B^-[/tex] = [tex]\frac{0.0252mol}{1L}=0.0252M[/tex]

The solubility constant expression for this reaction is:

[tex]K_{sp}=[A^{2+}][B^-]^2[/tex]

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

[tex]K_{sp}=(0.0252M)\times (0.0252M)^2[/tex]

[tex]K_{sp}=1.60\times 10^{-5}[/tex]

Thus, the value of [tex]K_{sp}[/tex] of the generic salt is, [tex]1.60\times 10^{-5}[/tex]