Solubility of a Substance in solution

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In summary, the solubility of Mg(OH)2 in a 0.55mol/L solution of KOH is dominated by the initial concentration of OH- in the solution, which is 0.55mol/L. This results in a simplified solubility expression of Ksp=[Mg2+](0.55)^2, which can be solved without having to use a cubic equation.
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xykiist
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What is the solubility of Mg(OH)2 in a 0.55mol/L solution of KOH if the Ksp of Mg(OH)2 is 9.0x10-12?

I figured out that the initial concentration of OH- in the solution is 0.55mol/L. I did an ICE table for Mg(OH)2 and (assume x represents an unknown concentration) found that the concentration of Mg2+ is x, and OH- is 0.55mol/L+2x.
So if I continue with it, I get to this point:

Ksp=[Mg2+][OH-]^2
9.0x10-12=x(2x+0.55)^2
When i expand it and move everything to the right, i get a cubic equation that takes a lot of time to solve and so I get the feeling I'm not approaching this correctly. Any help?
 
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Since the Ksp of MgOH2 is only 9X10-12, you see that the concentration of OH- is ABSOLUTELY DOMINATED by the concentration of OH- due to KOH, which is completely soluble at that concentration. Thus, the hydroxide term for your solubility expression is quite accurately approximated as (0.55)2.
 

1. What is solubility?

Solubility refers to the ability of a substance (known as the solute) to dissolve in a specific solvent to form a homogeneous mixture, known as a solution. It is typically measured in terms of the amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure.

2. How is solubility determined?

Solubility is determined by factors such as the chemical nature of the solute and solvent, temperature, and pressure. Generally, substances with similar polarities will dissolve in one another, while substances with different polarities will not. Temperature and pressure can also affect solubility, with most substances being more soluble at higher temperatures and pressures.

3. What is the solubility curve?

The solubility curve is a graphical representation of the relationship between the solubility of a substance and temperature. It shows the maximum amount of solute that can be dissolved in a given amount of solvent at different temperatures. The shape of the curve can vary depending on the substance, with some showing an increase in solubility as temperature increases, while others show a decrease.

4. Can solubility be affected by other substances?

Yes, solubility can be affected by the presence of other substances in the solution. For example, adding a substance that shares similar polarities with the solute can increase its solubility by creating more favorable interactions. On the other hand, adding a substance with different polarities can decrease solubility by disrupting the interactions between the solute and solvent.

5. How is solubility important in various industries?

Solubility plays a crucial role in many industries, such as pharmaceuticals, food and beverage, and agriculture. In pharmaceuticals, solubility affects the absorption and efficacy of drugs in the body. In the food and beverage industry, it is important for creating and maintaining desired flavors and textures. In agriculture, solubility is essential for the absorption of nutrients by plants in fertilizers. Understanding and controlling solubility is essential in these industries to ensure product quality and effectiveness.

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