Question

The molar solubility of magnesium carbonate Mg(CO3) is 1.8 x 10-4 mol/L. What is the Ksp for this compound?

Answer 1

Answer:

The Ksp for this compound is 3.24 * 10^-8

Explanation:

Step 1: Data given:

Molar solubility of MgCO3 = 1.8 * 10^-4 mol /L

Step 2: Calculate molarity

For an insoluble compound, its molar solubility tells you how many moles of the compound can be dissolved per liter of aqueous solution before reaching saturation.

In this case, it means that we can only dissolve  1.8 * 10^-4 moles  in a liter of water at that temperature.

Moles Mg^2+ =  1.8 * 10^-4 moles

Moles CO3^2- =  1.8 * 10^-4 moles

Since we're working with one liter of solution, we can say the molarity:

[Mg^2+] =  1.8 * 10^-4 M

[CO3^2-] =  1.8 * 10^-4 M

Step 3: Calculate Ksp

Ksp = [Mg^2+]*[CO3^2-]

Ksp =  1.8 * 10^-4 *  1.8 * 10^-4

Ksp = 3.24 * 10^-8

The Ksp for this compound is 3.24 * 10^-8