1. What is pH Calculation from OH⁻?

pH calculation from hydroxide ion concentration [OH⁻] is a fundamental concept in acid-base chemistry. The pH scale measures the acidity or basicity of a solution, with values below 7 indicating acidity, 7 being neutral, and values above 7 indicating basicity.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( pH \) — pH value (dimensionless)
• \( [OH⁻] \) — Hydroxide ion concentration (mol/L)

Explanation: This formula converts hydroxide ion concentration to pH value using the relationship between pH and pOH (pH + pOH = 14).

3. Importance of pH Calculation

Details: Accurate pH calculation is essential for various chemical processes, biological systems, environmental monitoring, and industrial applications where pH control is critical.

4. Using the Calculator

Tips: Enter hydroxide ion concentration in mol/L. The value must be positive and greater than zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is the formula pH = 14 + log[OH⁻]?
A: This formula is derived from the relationship pH + pOH = 14, where pOH = -log[OH⁻], so pH = 14 - (-log[OH⁻]) = 14 + log[OH⁻].

Q2: What is the valid range for [OH⁻] concentration?
A: The concentration should be between 10⁻¹⁴ mol/L and 1 mol/L for aqueous solutions at 25°C, corresponding to pH values between 0 and 14.

Q3: How accurate is this calculation?
A: The calculation provides theoretical pH values. In real solutions, activity coefficients and temperature effects may cause slight variations.

Q4: Can this calculator be used for very concentrated solutions?
A: For highly concentrated solutions (>1M), the calculation may be less accurate due to ionic strength effects and deviation from ideal behavior.

Q5: What about temperature effects?
A: The relationship pH + pOH = 14 is valid at 25°C. At other temperatures, the sum changes (e.g., 13.99 at 0°C, 13.62 at 100°C).