1. What is pH?

pH is a logarithmic measure of the hydrogen ion concentration in a solution. It indicates the acidity or basicity of a solution, with values below 7 being acidic and values above 7 being basic (at 25°C).

2. How Does the Calculator Work?

The calculator uses the pH equation:

Where:

• \( pH \) — pH value (dimensionless)
• \( [H^+] \) — Hydrogen ion concentration (mol/L)

Explanation: The equation shows the inverse logarithmic relationship between hydrogen ion concentration and pH. Each pH unit represents a tenfold difference in hydrogen ion concentration.

3. Importance of pH Calculation

Details: pH is critical in chemistry, biology, medicine, and environmental science. It affects chemical reactions, biological functions, and the behavior of molecules in solution.

4. Using the Calculator

Tips: Enter either the hydrogen ion concentration (to calculate pH) or the pH value (to calculate hydrogen ion concentration). Select the appropriate calculation type. All values must be valid (concentration > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the pH of pure water?
A: At 25°C, pure water has a pH of 7 (neutral) with [H+] = 1×10⁻⁷ mol/L.

Q2: How does temperature affect pH?
A: The pH of neutral water changes with temperature (e.g., pH 7.47 at 0°C, 6.14 at 100°C) because the ionization of water is temperature-dependent.

Q3: What's the relationship between pH and pOH?
A: pH + pOH = 14 (at 25°C). pOH is calculated similarly but uses hydroxide ion concentration [OH⁻].

Q4: Why is pH important in biological systems?
A: Most enzymes and biological processes function within narrow pH ranges. Human blood, for example, is tightly regulated around pH 7.4.

Q5: How accurate is this calculator?
A: The calculator provides theoretical values. Actual measurements may vary due to ionic strength, temperature, and other solution factors.