1. What is pH of Pure Water?

The pH of pure water is approximately 7 at 25°C, but changes with temperature due to the temperature dependence of the water dissociation constant (Kw).

2. How Does the Calculator Work?

The calculator uses the following approximation:

Where:

• Temperature Adjustment — Approximately 0.01 pH units per °C difference from 25°C

Explanation: The pH of pure water changes with temperature because the ionization of water is temperature-dependent.

3. Importance of pH Calculation

Details: Understanding how pH changes with temperature is important for laboratory work, industrial processes, and environmental studies where precise pH measurements are required.

4. Using the Calculator

Tips: Enter the temperature in degrees Celsius. The calculator will estimate the pH of pure water at that temperature.

5. Frequently Asked Questions (FAQ)

Q1: Why does pH of pure water change with temperature?
A: The ionization constant of water (Kw) changes with temperature, affecting the concentration of H+ and OH- ions.

Q2: What is the pH of pure water at 25°C?
A: Exactly 7.0 at 25°C, by definition of the pH scale.

Q3: Does this calculator work for salt water or other solutions?
A: No, this only calculates pH for pure water. Other solutions require different calculations.

Q4: How accurate is this calculation?
A: This is an approximation. For precise work, consult detailed thermodynamic tables.

Q5: At what temperature is pure water most acidic?
A: The pH decreases (becomes more acidic) as temperature increases, though it remains neutral as [H+] = [OH-].