Question

Determine the pOH of each solution.

1. [H3O+] = 3.3×10−10 M
Express your answer using two decimal places.
2. [H3O+] = 2.6×10−7 M
Express your answer using two decimal places.
3. [H3O+] = 5.3×10−2 M
Express your answer using two decimal places.
4. [OH−] = 1.32×10−4 M
Express your answer using three decimal places.

Answer 1

1. pOH = 5.519; 2. pOH = 6.585; 3. pOH = 12.725; 4. pOH = 3.879

Step-by-step explanation:

First of all, rembember this: water's equilibrium

2H₂O ⇄ H₃O⁺ + OH⁻

The expression for Kw = [H₃O⁺] . [OH⁻] → 1x10⁻¹⁴

[H₃O⁺] = 1x10⁻¹⁴ / [OH⁻]

[OH⁻] = 1x10⁻¹⁴ / [H₃O⁺]

-log [H₃O⁺] = pH

-log [OH⁻] = pOH

pH + pOH = 14 because pKw = 14

1. -log 3.3×10⁻¹⁰ = 9.481

14 - 9.481 = 5.519

2. -log 2.6×10⁻⁷ = 6.585

14 - 6.585 = 7.415

3. -log 5.3×10⁻² = 1.275

14 - 1.275 = 12.725

4. - log 1.32×10⁻⁴ = 3.879