Question

What is the ph of a saturated solution of zn(oh)2? ksp = 1.8 × 10−14

Answer 1

To find the pH of a saturated solution of Zn(OH)2 with a given Ksp of 1.8 × 10−14, we calculate the solubility 's', determine the pOH, and then subtract the pOH from 14.00 to obtain the pH.

Step-by-step explanation:

To determine the pH of a saturated solution of Zn(OH)2, we need to use the solubility product constant (Ksp). For Zn(OH)2, which dissociates into Zn2+ and 2OH- in water, the Ksp expression is:

Ksp = [Zn2+][OH-]2

Given the Ksp is 1.8 × 10−14, if we let 's' represent the solubility of Zn(OH)2, then we have:

[Zn2+] = s

[OH-] = 2s

Plugging these into the Ksp expression, we get:

1.8 × 10−14 = s × (2s)2 = 4s3

Solving for s, we find:

s = −6.50 × 10−5 M

Next, we can calculate the pOH:

pOH = -log(2s) = -log(2 × 6.50 × 10−5)

Finally, we can determine the pH, knowing that at 25 °C:

pH + pOH = 14.00

Therefore, by subtracting the pOH from 14.00, we can find the pH of the solution.

Answer 2

The pH of a saturated solution of Zn(OH)2 is 7.00, which is neutral.

Step-by-step explanation:

A saturated solution of Zn(OH)2 can be considered as a mixture of Zn²+ ions and OH- ions. The solubility product constant (Ksp) for Zn(OH)2 is 1.8 × 10^-14, which represents the equilibrium between the dissociated ions and the undissolved solid. To calculate the pH of the solution, we need to determine the concentration of OH- ions. Since OH- is the conjugate base of water, we can use the autoionization constant of water (Kw) to calculate the concentration of OH- ions. The expression for Kw is Kw = [H+][OH-] = 1.0 × 10^-14, where [H+] represents the concentration of H+ ions. Since water is neutral, the concentrations of H+ and OH- ions are equal in a neutral solution, so the concentration of OH- ions in a neutral solution would be 1.0 × 10^-7 M. The pH of a solution can be calculated using the equation pH = -log[H+]. Therefore, the pH of a saturated solution of Zn(OH)2 would be 7.00, which is neutral.