Question

What is the hydroxide-ion concentration of an aqueous solution having a hydronium-ion concentration of 1.905 × 10⁻⁵ mol/L?

Answer 1

Solution:

[H₃O⁺] = 1.905×10⁻⁵ mol/L

The hydroxide ion concentration can be calculated using the K_w constant:

K_w = [H₃O⁺]×[OH⁻] = 1.0×10^-14

Therefore,

[OH⁻] = K_w / [H₃O⁺]

[OH⁻] = (1.0×10⁻¹⁴) / (1.905×10⁻⁵) = 5.249×10⁻¹⁰

[OH⁻] = 5.249×10⁻¹⁰ M

Answer: [OH⁻] = 5.249×10⁻¹⁰ M