Question

Calculate the [OH−] of each aqueous solution with the following [H3O+].

Express your answer using two significant figures.

Part 1: soap, 1.2×10⁻⁸ M

OH{-} = ?

Part 2: cleanser, 5.2×10⁻¹⁰ M

OH{-} = ?

Part 3: lemon juice, 2.6×10⁻² M

OH{-} = ?

Problem 10.33

Answer 1

1)

we have below equation to be used:

[OH-] = Kw/[H3O+]

Kw is dissociation constant of water whose value is 1.0*10^-14 at 25 oC

[OH-] = (1.0*10^-14)/[H3O+]

[OH-] = (1.0*10^-14)/(1.2*10^-8)

[OH-] = 8.33*10^-7 M

Answer: 8.3*10^-7 M

2)

we have below equation to be used:

[OH-] = Kw/[H3O+]

Kw is dissociation constant of water whose value is 1.0*10^-14 at 25 oC

[OH-] = (1.0*10^-14)/[H3O+]

[OH-] = (1.0*10^-14)/(5.2*10^-10)

[OH-] = 1.92*10^-5 M

Answer: 1.9*10^-5 M

3)

we have below equation to be used:

[OH-] = Kw/[H3O+]

Kw is dissociation constant of water whose value is 1.0*10^-14 at 25 oC

[OH-] = (1.0*10^-14)/[H3O+]

[OH-] = (1.0*10^-14)/(2.6*10^-2)

[OH-] = 3.8*10^-13 M

Answer: 3.8*10^-13 M