Question

Calculate the pH of each solution given the following [H3O+] or [OH−] values.

a.) [H3O+] = 5.0×10⁻⁴ M

Express your answer using two decimal places.

b.) [H3O+] = 6.0×10⁻⁹ M

Express your answer using two decimal places.

c.) [OH−] = 4.0×10⁻⁵ M

Express your answer using two decimal places.

d.) [OH−] = 1.5×10⁻¹¹ M

Express your answer using two decimal places.

e.) [H3O+] = 6.8×10⁻⁸ M

Express your answer using two decimal places.

f.) [OH−] = 7.8×10⁻⁴ M

Express your answer using two decimal places.

Answer 1

a) Concentration ofH₃0⁺ = 5.0 * 10^-4M

Resultant pH of the solution, pH = -log[H₃O⁺] = -log (5.0 * 10^-4) = 3.30

b) Concentration ofH₃0⁺ = 6.0 * 10^-9M

Resultant pH of the solution, pH = -log[H₃O⁺] = -log (6.0 * 10^-9) = 8.22

c) [OH^-] = 4.0 * 10^-5M

Resultant pOH of the solution, pOH = -log[OH^-] = -log (4.0 * 10^-5) = 4.40

pH = 14.00 - pOH = 14.00 – 4.40

= 9.60

d) [OH^-] = 1.5 * 10^-11M

Resultant pOH of the solution, pOH = -log[OH^-] = -log (1.5 * 10^-11) = 10.82

pH = 14.00 - pOH = 14.00 – 10.82 = 3.18

e) Concentration of H₃0⁺ = 6.8 * 10^-8M