1. What is OH- Concentration?

The hydroxide ion concentration ([OH⁻]) is a measure of the alkalinity of an aqueous solution. In water, 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 formula:

Where:

• \( [OH^-] \) — Hydroxide ion concentration (mol/L)
• \( pH \) — The pH value of the solution (0-14 scale)
• 14 — The pKw value for water at 25°C

Explanation: The formula derives from the relationship pH + pOH = 14, where pOH = -log[OH⁻].

3. Importance of OH- Calculation

Details: Knowing the hydroxide ion concentration is essential for understanding solution alkalinity, chemical reaction rates, and biological systems where pH balance is crucial.

4. Using the Calculator

Tips: Enter the pH value (between 0 and 14). The calculator will compute the corresponding hydroxide ion concentration in mol/L.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between pH and OH- concentration?
A: They are logarithmically related. As pH increases (more alkaline), OH- concentration increases exponentially.

Q2: What are typical OH- concentrations in water?
A: In neutral water (pH 7), [OH⁻] = 1×10⁻⁷ mol/L. At pH 10, [OH⁻] = 1×10⁻⁴ mol/L.

Q3: Does temperature affect this calculation?
A: Yes, the pKw value changes with temperature. This calculator assumes standard conditions (25°C).

Q4: Can this be used for solutions other than water?
A: The basic relationship holds for dilute aqueous solutions, but ionic strength effects may require corrections.

Q5: How precise is this calculation?
A: It's mathematically exact for ideal solutions at 25°C. Real solutions may show slight deviations.