1. What is the Nernst Equation for pH to mV?

The Nernst equation describes the relationship between pH and millivolt (mV) output from a pH electrode at 25°C. It provides the theoretical basis for pH meter calibration and measurement.

2. How Does the Calculator Work?

The calculator uses the Nernst equation:

Where:

• \( mV \) — Millivolt output from pH electrode
• \( E0 \) — Standard electrode potential (mV)
• \( pH \) — pH value (unitless)
• 59.16 — Nernst slope at 25°C (mV/pH unit)

Explanation: The equation shows that for each unit change in pH, the electrode potential changes by approximately 59.16 mV at 25°C.

3. Importance of pH to mV Conversion

Details: Understanding the relationship between pH and mV is crucial for pH meter calibration, electrode performance verification, and accurate pH measurement in various scientific and industrial applications.

4. Using the Calculator

Tips: Enter the standard electrode potential (E0) in mV and the pH value. The calculator will compute the corresponding mV output based on the Nernst equation at 25°C.

5. Frequently Asked Questions (FAQ)

Q1: Why is the slope 59.16 mV per pH unit?
A: This value comes from the Nernst equation constants (RT/F) at 25°C, where R is the gas constant, T is temperature, and F is Faraday's constant.

Q2: Does temperature affect the slope?
A: Yes, the Nernst slope changes with temperature. The 59.16 value is specific to 25°C. At other temperatures, the slope is approximately 0.1984 × T (in Kelvin).

Q3: What is a typical E0 value?
A: E0 varies between electrodes but is typically around 0 mV for a properly calibrated pH electrode at pH 7.0.

Q4: How accurate is this calculation?
A: The calculation provides the theoretical mV value. Actual electrode performance may vary due to factors like electrode age, condition, and solution composition.

Q5: Can this be used for electrode calibration?
A: Yes, this equation forms the basis for two-point pH electrode calibration using standard buffer solutions.