1. What is the pH to OH- Calculation?

The pH to OH- calculation determines the concentration of hydroxide ions in a solution based on its pH value. This is fundamental in chemistry for understanding solution alkalinity and acid-base balance.

2. How Does the Calculator Work?

The calculator uses the pH to OH- equation:

Where:

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

Explanation: The equation derives from the relationship between pH, pOH, and the ion product of water (Kw = 10^-14 at 25°C).

3. Importance of OH- Concentration

Details: Hydroxide ion concentration is crucial for determining solution alkalinity, chemical reaction rates, and biological system functioning. It's used in water treatment, industrial processes, and medical applications.

4. Using the Calculator

Tips: Enter pH value between 0 and 14. The calculator will display the OH- concentration in both scientific notation and decimal form.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between pH and OH- concentration?
A: They have an inverse logarithmic relationship through the equation pH + pOH = 14 at 25°C.

Q2: What are typical OH- concentrations?
A: In neutral water (pH 7), [OH-] is 10^-7 mol/L. In strong bases (pH 14), [OH-] approaches 1 mol/L.

Q3: Does temperature affect this calculation?
A: Yes, the pKw changes with temperature (e.g., 13.99 at 37°C), but this calculator uses the standard 25°C value.

Q4: Can this be used for very concentrated solutions?
A: The calculation becomes less accurate for very high ionic strength solutions where activity coefficients differ significantly from 1.

Q5: How is OH- concentration measured experimentally?
A: Common methods include pH meters (indirectly), titration with acids, or specific ion electrodes.