Question

For each of the following strong base solutions, determine [OH−],[H3O+], pH, and pOH. 1.) 0.11 M NaOH 2.) 1.2×10−3 M Ca(OH)2 3.) 4.7×10−4 M Sr(OH)2 4.) 8.6×10−5 M KOH

Answer 1

1.) 0.11 M NaOH

[OH-] = 0.11 M

[H3O+] = Kw / [OH-] = 1 x 10^-14 / 0.11

           = 9.09 x 10^-14 M

pH = -log[H3O+]

pH = 13.04

pH + pOH = 14

pOH = 0.96

2.) 1.2×10−3 M Ca(OH)2

[OH-] = 0.0024 M

[H3O+] = 4.17 x 10^-12 M

pH = 11.38

pOH = 2.62

3.) 4.7×10−4 M Sr(OH)2

[OH-] = 9.4 x 10^-4 M

[H3O+] = 1.06 x 10^-11 M

pH = 10.97

pOH = 3.03

4.) 8.6×10−5 M KOH

[OH-] =8.6×10^−5 M

[H3O+] = 1.16 x 10^-10 M

pH = 9.93

pOH = 4.07