Answer to Question #349291 in General Chemistry for brenda ferrilus

Question

 0.000675 M calcium hydroxide

Answer 1

C_M [Ca(OH)₂] = 0,000675 M = 6,75 * 10^-4

pH = ?

1.

We find the OH^– ion concentration

Ca(OH)₂ => Ca²⁺ + 2OH^–

1mol Ca(OH)₂ => 2mol OH^–

6,75 * 10^-4 M => X

X = 6,75 * 10^-4 * 2 / 1 = 1,35 * 10^-3 M

2.

We find the pOH:

pOH = -log [OH^–]

pOH = -log (1,35 * 10^-3) = 3- log (1,35) = 2,87

3.

Using the sum of pH and pOH equal 14 in any solution, we find the pH:

pH + pOH = 14

pH = 14 - pOH = 14 - 2,87 = 11,13

Answer: pH = 11,13