Question

Determine the hydroxide ion concentration in
a solution that is 0.00043 M Ca(OH)2.

Answer 1

Answer: Ca(OH)2 = Ca2+ + 2 OH-

the ratio between Ca(OH)2 and OH- is 1 : 2

Explanation: [OH-]= 2 x 0.00034 = 0.00068 M

[H+]= Kw/[OH-]= 1.0 x 10^-14 / 0.00068 =1.5 x 10^-11 M ( at two significant figures)

HCl is a monoprotic acid

[H+]= 0.00031 M

[OH-]= Kw/[H+]= 1.0 x 10^-14 / 0.00031 =3.2 x 10^-11 M

[OH-]= 0.047 M

[H+]= 1.0 x 10^-14 / 0.047 =2.1 x 10^-13 M