1. What is Hydrogen Ion Concentration?

The hydrogen ion concentration [H⁺] is a measure of the acidity of a solution. It is directly related to pH, which is a logarithmic scale used to specify the acidity or basicity of an aqueous solution.

2. How Does the Calculator Work?

The calculator uses the fundamental pH equation:

Where:

• \( [H^+] \) — Hydrogen ion concentration in moles per liter (mol/L)
• \( pH \) — The pH value (unitless, ranging from 0 to 14)

Explanation: The pH scale is logarithmic, meaning each whole pH value below 7 is ten times more acidic than the next higher value.

3. Importance of pH and [H⁺]

Details: Hydrogen ion concentration is crucial in chemistry, biology, medicine, and environmental science. It affects chemical reactions, enzyme function, and many biological processes.

4. Using the Calculator

Tips: Enter a pH value between 0 (very acidic) and 14 (very basic). The calculator will compute the corresponding hydrogen ion concentration in mol/L.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between pH and [H⁺]?
A: pH is the negative logarithm (base 10) of the hydrogen ion concentration: \( pH = -\log[H^+] \).

Q2: What is the [H⁺] of pure water?
A: Pure water at 25°C has pH 7, so [H⁺] = 10⁻⁷ = 0.0000001 mol/L.

Q3: How does temperature affect pH and [H⁺]?
A: The pH of pure water changes with temperature as the water dissociation constant changes, though [H⁺] = [OH⁻] remains true.

Q4: What's the [H⁺] in stomach acid?
A: Stomach acid typically has pH 1.5-3.5, corresponding to [H⁺] ≈ 0.03-0.0003 mol/L.

Q5: Why use scientific notation for very small [H⁺] values?
A: Scientific notation conveniently represents the wide range of concentrations encountered (from ~1 mol/L at pH 0 to 10⁻¹⁴ mol/L at pH 14).