Question

Calculate the [H₃O⁺] and [OH^-] for a solution with each of the following pH values. Express your answer to one significant figure and include the appropriate units:

1.) What is the [H₃O⁺] for a solution with pH = 10.60?

[H₃O⁺] =

2.) What is the [OH^-] for the solution above?

[OH^-] =

3.) What is the [H₃O⁺] for a solution with pH = 5.3?

[H₃O⁺] =

4.) What is the [OH^-] for the solution above?

[OH^-] =

5.) What is the [H₃O⁺] for a solution with pH = 6.51?

[H₃O⁺] =

6.) What is the [OH^-] for the solution above?

[OH^-] =

7.) What is the [H₃O⁺] for a solution with pH = 1.83?

[H₃O⁺] =

8.) What is the [OH^-] for the solution above?

[OH^-] =

Answer 1

1)

use:

pH = -log [H3O+]

10.6 = -log [H3O+]

[H3O+] = 2.512*10^-11 M

Answer: 3*10^-11 M

2)

use:

[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)/(2.512*10^-11)

[OH-] = 3.981*10^-4 M

Answer: 4*10^-4 M

3)

use:

pH = -log [H3O+]

5.3 = -log [H3O+]

[H3O+] = 5.012*10^-6 M

Answer: 5*10^-6 M

4)

use:

[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)/(5.012*10^-6)

[OH-] = 1.995*10^-9 M

Answer: 2*10^-9 M

Only 4 parts at a time