1. What is Hydroxide Ion Concentration?

Hydroxide ion concentration ([OH⁻]) represents the molar concentration of hydroxide ions in a solution. It is inversely related to pH and directly indicates the basicity of a solution at 25°C.

2. How Does the Calculator Work?

The calculator uses the hydroxide ion concentration equation:

Where:

• \( [OH⁻] \) — Hydroxide ion concentration (mol/L)
• \( pH \) — pH value (dimensionless, 0-14 scale)

Explanation: This equation calculates the hydroxide ion concentration from pH at standard temperature (25°C), based on the water ion product constant Kw = 10⁻¹⁴.

3. Importance of pH and [OH⁻] Relationship

Details: Understanding the relationship between pH and hydroxide ion concentration is essential in chemistry, biology, environmental science, and various industrial processes where pH control is critical.

4. Using the Calculator

Tips: Enter pH value (0-14 scale). The calculator will compute the corresponding hydroxide ion concentration in moles per liter (mol/L) at 25°C.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 14 used in the equation?
A: The constant 14 comes from the negative logarithm of the water ion product (pKw = 14 at 25°C), where Kw = [H⁺][OH⁻] = 10⁻¹⁴.

Q2: Does this equation work at temperatures other than 25°C?
A: No, this specific equation is valid only at 25°C. The water ion product Kw changes with temperature, affecting the relationship between pH and [OH⁻].

Q3: What are typical [OH⁻] values for common solutions?
A: Neutral water (pH 7): 10⁻⁷ mol/L, Basic solutions (pH >7): >10⁻⁷ mol/L, with pH 14 giving 1 mol/L [OH⁻].

Q4: How is [OH⁻] related to pOH?
A: pOH = -log[OH⁻], and pH + pOH = 14 at 25°C. The two are complementary measurements of solution basicity.

Q5: When is hydroxide ion concentration measurement important?
A: Crucial in titration experiments, water treatment, chemical manufacturing, and biological systems where pH balance affects chemical reactions and biological functions.