Question

A metal Hydroxide of molecular formula M(OH)3 is 50% ionized. Its 0.025 M solution will have PH_
Opt 1__ 12
Opt2__2
Opt3__4
Opt4__11.7

Answer 1

The dissociation of M(OH)3 is follows:

M(OH)3  M3+ + 3 OH-

Concentration of hydroxide ion is

[OH] = 3 * 0.025 = 0.075 M

As, 50 % ionisation takes place and thus the concentration of hydroxyde ion get reduced to half as follows:

[OH] = 0.075 /2 = 0.0375 M

pOH can be determined as:

pOH = - log (OH)

= - log (0.0375) = 1.461

pH + pOH = 14

pH + 1.461 = 14

pH = 12. 539

Thus, pH of metal hydroxide is 12.539

Answer 2

Sorry, but the answer is 11.7