Question

What is the concentration of a magnesium hydroxide solution with a pH of 12.05

Answer 1

Answer:

5.6x10^–3 M

Explanation:

We'll begin by calculating the pOH of the solution. This can be achieved as shown below:

pH + pOH = 14

pH = 12.05

12.05 + pOH = 14

Collect like terms

pOH = 14 – 12.05

pOH = 1.95

Next, we shall determine the concentration of hydroxide ion OH- in the solution. This is illustrated below:

pOH = – Log [OH-]

pOH = 1.95

1.95 = – Log [OH-]

– 1.95 = Log [OH-]

[OH-] = anti log (– 1.95)

[OH-] = 0.0112 M

Finally, we can obtain the concentration of Mg(OH)2 as follow:

In solution, Mg(OH)2 will dissociates as shown below:

Mg(OH)2 —> Mg2+ + 2OH-

From the balanced equation above,

1 mole of Mg(OH)2 produced 2 moles of OH-.

Therefore, XM of Mg(OH)2 will produce 0.0112 M of OH- i.e

XM of Mg(OH)2 = 0.0112/2

XM of Mg(OH)2 = 5.6x10^–3 M

Therefore, the concentration of Mg(OH)2 is 5.6x10^–3 M