The Ksp of Aluminum Hydroxide is 4.6 x 10-33. What is the molar solubility of Al(OH)3 and what mass could dissolve in 200 ml of water?

Question

need to fine the molar solubility and what mass could dissolve in 200 ml of water

Answer 1

Write the equation for the dissolving of the compound:

Al(OH)₃ --> Al(aq) + 3OH^-(aq)

K_SP = [Al³⁺][OH^-]³

Let x be the moles of Al(OH)₃ dissolved in 1 liter (we can always adjust the answer for .2 liters at the end -- the answer will be .2 x the answer for 1 liter). That means the [Al³⁺] is x Molar and [OH^-] is 3x

The K expression becomes: 4.6 x 10^-33 = x (3x)³ = 27x⁴

Solve for x, multiply by 0.2 to get moles, and multiply by g/mole for the compound to get grams.