1. What is pH?

pH is a measure of the acidity or basicity of an aqueous solution. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration. The pH scale ranges from 0 to 14, with 7 being neutral, values below 7 acidic, and values above 7 basic.

2. How Does the Calculator Work?

The calculator uses the pH formula:

Where:

• \( [H^+] \) — Hydrogen ion concentration in moles per liter (mol/L)
• \( \log_{10} \) — Logarithm base 10

Explanation: The pH value is calculated by taking the negative base-10 logarithm of the hydrogen ion concentration in a solution.

3. Importance of pH Calculation

Details: pH is critical in many chemical and biological processes. It affects enzyme activity, chemical solubility, and biological functions. Maintaining proper pH is essential in medicine, agriculture, water treatment, and many industrial processes.

4. Using the Calculator

Tips: Enter the hydrogen ion concentration in mol/L (moles per liter). The value must be greater than 0. For example, pure water at 25°C has [H+] of 1.0 × 10⁻⁷ mol/L.

5. Frequently Asked Questions (FAQ)

Q1: What is the pH of a neutral solution?
A: At 25°C, a neutral solution has a pH of 7.0 (where [H+] = 1.0 × 10⁻⁷ mol/L).

Q2: How does temperature affect pH?
A: The pH of neutral water changes with temperature because the ionization of water is temperature-dependent. The pH of pure water at 100°C is about 6.14.

Q3: What is the relationship between pH and pOH?
A: In aqueous solutions at 25°C, pH + pOH = 14. pOH is calculated similarly using hydroxide ion concentration.

Q4: What are typical pH values for common substances?
A: Gastric acid: 1.5-3.5, Lemon juice: ~2.4, Coffee: ~5, Blood: 7.35-7.45, Soapy water: ~10, Bleach: ~12.5.

Q5: How precise is pH measurement?
A: pH meters can measure to ±0.01 pH units, but biological systems often have natural variations of 0.1-0.3 pH units.