Describe the process by which adding potassium hydroxide to a saturated aluminum hydroxide solution reduces the concentration of aluminum ions. Write the solubility equilibrium equation and solubility product constant expression for a saturated aqueous solution of aluminum hydroxide.

You need this equation.

Al^+3 + 3OH^- ==> Al(OH)3(s)
Al(OH)3(s) + OH^- ==> Al(OH)4^-

Adding more KOH shifts the equilibrium of both equations to the right.

The process by which adding potassium hydroxide (KOH) to a saturated aluminum hydroxide (Al(OH)3) solution reduces the concentration of aluminum ions can be explained by the concept of solubility equilibrium.

When aluminum hydroxide dissolves in water, it undergoes a dissociation reaction in which aluminum ions (Al3+) and hydroxide ions (OH-) are released:

Al(OH)3(s) ⇌ Al3+(aq) + 3OH-(aq)

However, aluminum hydroxide has a limited solubility in water and reaches a point of saturation where the concentration of dissolved aluminum ions is at its maximum.

When potassium hydroxide is added to the saturated solution, it introduces more hydroxide ions to the system. These hydroxide ions react with the aluminum ions to form aluminum hydroxide, which has lower solubility compared to the initial aluminum hydroxide:

Al3+(aq) + 3OH-(aq) ⇌ Al(OH)3(s)

This reaction effectively removes aluminum ions from the solution, thereby reducing their concentration. The dissolution of aluminum hydroxide is suppressed, leading to a decrease in the concentration of aluminum ions.

The solubility equilibrium equation for the dissolution of aluminum hydroxide is:

Al(OH)3(s) ⇌ Al3+(aq) + 3OH-(aq)

The solubility product constant expression (Ksp) for aluminum hydroxide can be written as:

Ksp = [Al3+][OH-]^3

where [Al3+] represents the concentration of aluminum ions and [OH-] represents the concentration of hydroxide ions. The value of Ksp determines the solubility of aluminum hydroxide at a given temperature.