1. What is Hydroxide Ion Concentration?

The hydroxide ion concentration ([OH-]) is a measure of the basicity of a solution. It is inversely related to the hydrogen ion concentration ([H+]) through the ion product of water (Kw = 1×10⁻¹⁴ at 25°C).

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• \( [OH^-] \) — Hydroxide ion concentration (M)
• \( K_w \) — Ion product of water (1×10⁻¹⁴ at 25°C)
• \( [H^+] \) — Hydrogen ion concentration (M)

3. Importance of [OH-] Calculation

Details: Knowing the hydroxide ion concentration is essential for understanding solution pH, calculating pOH, and determining the basicity of solutions in chemical and biological systems.

4. Using the Calculator

Tips: Enter the hydrogen ion concentration in molarity (M). The value must be positive and greater than zero. The calculator will compute the corresponding hydroxide ion concentration.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between [OH-] and pH?
A: pOH = -log[OH-], and pH + pOH = 14 at 25°C. As [OH-] increases, pH increases (solution becomes more basic).

Q2: What is the [OH-] in pure water at 25°C?
A: In pure water, [H+] = [OH-] = 1×10⁻⁷ M, giving a neutral pH of 7.

Q3: Does Kw change with temperature?
A: Yes, Kw is temperature-dependent. The value 1×10⁻¹⁴ is specific to 25°C.

Q4: What are typical [OH-] values for acidic and basic solutions?
A: Acidic solutions have [OH-] < 1×10⁻⁷ M, basic solutions have [OH-] > 1×10⁻⁷ M.

Q5: Can this calculator be used for very concentrated solutions?
A: For highly concentrated solutions (>0.1 M), activity coefficients should be considered for precise calculations.