1. What is Hydroxide Ion Concentration?

The hydroxide ion concentration [OH-] is a measure of the alkalinity of a solution. It is inversely related to the hydrogen ion concentration [H+] through the water ion product constant (Kw).

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( [OH^-] \) — Hydroxide ion concentration (mol/L)
• \( K_w \) — Water ion product constant (1.0 × 10⁻¹⁴ mol²/L² at 25°C)
• \( [H^+] \) — Hydrogen ion concentration (mol/L)

Explanation: The formula shows the inverse relationship between [OH-] and [H+] in aqueous solutions at equilibrium.

3. Importance of [OH-] Calculation

Details: Calculating hydroxide ion concentration is essential for determining solution pH, understanding acid-base chemistry, and in various chemical and biological processes.

4. Using the Calculator

Tips: Enter the hydrogen ion concentration in mol/L. The value must be positive and non-zero. The result will be displayed in scientific notation for very small concentrations.

5. Frequently Asked Questions (FAQ)

Q1: What is the value of Kw?
A: The water ion product constant (Kw) is 1.0 × 10⁻¹⁴ mol²/L² at 25°C (standard conditions).

Q2: How does temperature affect Kw?
A: Kw increases with temperature. At body temperature (37°C), Kw ≈ 2.5 × 10⁻¹⁴ mol²/L².

Q3: What is the relationship between pH and [OH-]?
A: pH + pOH = 14 at 25°C, where pOH = -log[OH-].

Q4: What are typical [OH-] values?
A: In neutral water at 25°C, [OH-] = 1 × 10⁻⁷ mol/L. In acidic solutions it's less, in basic solutions it's more.

Q5: Can this calculator be used for any temperature?
A: This calculator uses the standard Kw value for 25°C. For other temperatures, you would need to adjust Kw accordingly.