Here's how to understand the OH⁻ concentration in a sulfuric acid solution:
* First Ionization: H₂SO₄ completely ionizes in water, donating one proton to form HSO₄⁻ (hydrogen sulfate ion) and H₃O⁺ (hydronium ion).
* H₂SO₄ (aq) + H₂O (l) → HSO₄⁻ (aq) + H₃O⁺ (aq)
* Second Ionization: HSO₄⁻ also ionizes, but to a lesser extent, donating another proton to form SO₄²⁻ (sulfate ion) and another H₃O⁺.
* HSO₄⁻ (aq) + H₂O (l) ⇌ SO₄²⁻ (aq) + H₃O⁺ (aq)
The high concentration of H₃O⁺ ions significantly lowers the OH⁻ concentration due to the ion product constant of water (Kw):
* Kw = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25°C
Therefore, the OH⁻ concentration in a sulfuric acid solution is extremely low. To calculate the exact value, you would need to know the concentration of the sulfuric acid solution and consider both ionization steps.
Key Points:
* Sulfuric acid is a strong acid, meaning it ionizes completely in solution.
* The presence of H₃O⁺ ions from the acid significantly reduces the OH⁻ concentration.
* The exact OH⁻ concentration depends on the concentration of the sulfuric acid solution.
