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The solubility product constant for MX2 is 7.2 x 10-8. How many grams of MX2 (108.75 g/mol) will dissolve in 276 ml of water at 25°C. M is the metal and X is the anion. Enter as a number to 4 decimal places.

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Answer: The mass of [tex]MX_2[/tex] that will dissolve is 0.0786 grams

Explanation:

Solubility product is defined as the product of concentration of ions present in a solution each raised to the power its stoichiometric ratio.

The chemical equation for the ionization of [tex]MX_2[/tex] follows:

[tex]MX_2(aq.)\rightleftharpoons M^{2+}(aq.)+2X^-(aq.)[/tex]

                        s               2s

The expression of [tex]K_{sp}[/tex] for above equation follows:

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

We are given:

[tex]K_{sp}=7.2\times 10^{-8}[/tex]

Putting values in above expression, we get:

[tex]7.2\times 10^{-8}=s\times (2s)^2\\\\s=2.62\times 10^{-3}M[/tex]

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}[/tex]

Molar mass of [tex]MX_2[/tex] = 108.75 g/mol

Molarity of solution = [tex]2.62\times 10^{-3}mol/L[/tex]

Volume of solution = 276 mL

Putting values in above equation, we get:

[tex]2.62\times 10^{-3}mol/L=\frac{\text{Mass of }MX_2\times 1000}{108.75/mol\times 276}\\\\\text{Mass of }MX_2=\frac{2.62\times 10^{-3}\times 108.75\times 276}{1000}=0.0786g[/tex]

Hence, the mass of [tex]MX_2[/tex] that will dissolve is 0.0786 grams

The mass of MX₂ that will dissolve is 0.0786 grams.

What is Solubility Product?

Solubility product is defined as the product of concentration of ions present in a solution each raised to the power its stoichiometric ratio.

The chemical equation for the ionization of  follows:

[tex]MX_2--- > M^{2+}+2X^-[/tex]

                       s           2s

Calculation for "s" :

Given: [tex]K_{sp}= 7.2*10^{-8}[/tex]

[tex]K_{sp}=s*(2s)^2\\\\7.2*10^{-8}=s*(2s)^2\\\\s=2.62*10^{-3}M[/tex]

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

M = n/ V

Molar mass of  = 108.75 g/mol

Molarity of solution = [tex]2.62*10^{-3}mol/L[/tex]

Volume of solution = 276 mL

On substituting the values:

[tex]2.62*10^{-3} mol/L=\frac{\text{ Mass of } MX_2 * 1000}{108.75g/mol*276} \\\\\text{ Mass of } MX_2=\frac{2.62*10^{-3} mol/L*108.75g/mol*276}{1000} \\\\\text{ Mass of } MX_2=0.0786 g[/tex]

Hence, the mass of MX₂ that will dissolve is 0.0786 grams.

Find more information about Solubility product here:

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