Hydrogen Ion Concentration Calculator

Calculate [H⁺], pH, pOH, and [OH⁻] from any value.

Enter any one value (pH, pOH, [H⁺], or [OH⁻]) to instantly calculate all related acid-base properties. This tool helps you understand acid-base equilibrium and water chemistry.

Examples

See how to use the Hydrogen Ion Concentration Calculator in real scenarios.

Calculate [H⁺] from pH 3

pH

Find the hydrogen ion concentration for a solution with pH 3.

Input Type: ph

pH Value: 3

pOH Value: undefined

[H⁺] (mol/L): undefined mol/L

[OH⁻] (mol/L): undefined mol/L

Find pH from [H⁺] = 2.5e-5 mol/L

[H⁺] (mol/L)

Calculate the pH of a solution with [H⁺] = 2.5 × 10⁻⁵ mol/L.

Input Type: h

pH Value: undefined

pOH Value: undefined

[H⁺] (mol/L): 2.5e-5 mol/L

[OH⁻] (mol/L): undefined mol/L

Get [H⁺] from [OH⁻] = 1e-9 mol/L

[OH⁻] (mol/L)

Determine the hydrogen ion concentration when [OH⁻] = 1 × 10⁻⁹ mol/L.

Input Type: oh

pH Value: undefined

pOH Value: undefined

[H⁺] (mol/L): undefined mol/L

[OH⁻] (mol/L): 1e-9 mol/L

Calculate [H⁺] from pOH 5

pOH

Find the hydrogen ion concentration for a solution with pOH 5.

Input Type: poh

pH Value: undefined

pOH Value: 5

[H⁺] (mol/L): undefined mol/L

[OH⁻] (mol/L): undefined mol/L

Other Titles
Understanding Hydrogen Ion Concentration: A Comprehensive Guide
Master the concepts of pH, pOH, [H⁺], and [OH⁻] with practical examples and clear explanations.

What is Hydrogen Ion Concentration?

  • Definition of [H⁺] and its importance
  • Relationship between pH, pOH, [H⁺], and [OH⁻]
  • Role in acid-base chemistry
Hydrogen ion concentration ([H⁺]) is a measure of the number of hydrogen ions present in a solution. It is a key indicator of a solution's acidity or basicity and is fundamental in understanding acid-base chemistry.
[H⁺] and pH Relationship
The pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration: pH = -log10([H⁺]). This relationship allows chemists to easily express very small concentrations in a manageable format.

Example Calculations

  • A solution with [H⁺] = 1e-7 mol/L has a pH of 7 (neutral).
  • If [H⁺] = 1e-3 mol/L, the pH is 3 (acidic).

Step-by-Step Guide to Using the Calculator

  • Choosing the correct input type
  • Entering values accurately
  • Interpreting the results
How to Use the Calculator
1. Select the input type (pH, pOH, [H⁺], or [OH⁻]). 2. Enter the value in the corresponding field. 3. Click 'Calculate' to see all related values instantly.
The calculator will automatically compute the other values and indicate whether the solution is acidic, neutral, or basic.

Step-by-Step Examples

  • Input pH = 4, get [H⁺] = 1e-4 mol/L, pOH = 10, [OH⁻] = 1e-10 mol/L.
  • Input [OH⁻] = 1e-8 mol/L, get pOH = 8, pH = 6, [H⁺] = 1e-6 mol/L.

Real-World Applications of Hydrogen Ion Concentration

  • Water quality and environmental science
  • Industrial and laboratory processes
  • Biological and medical relevance
Why [H⁺] Matters
Hydrogen ion concentration is crucial in water quality testing, environmental monitoring, and many industrial processes. It also plays a vital role in biological systems, such as blood pH regulation.
Accurate measurement and calculation of [H⁺] help ensure safety, product quality, and compliance with regulations.

Practical Applications

  • Testing the acidity of rainwater to monitor acid rain.
  • Adjusting pH in swimming pools or aquariums.

Common Misconceptions and Correct Methods

  • Misunderstanding pH and [H⁺] scales
  • Incorrect use of logarithms
  • Ignoring significant figures
Avoiding Calculation Errors
A common mistake is confusing pH and [H⁺] values or misapplying the logarithmic relationship. Always use the correct formula: [H⁺] = 10^(-pH).
Remember to use significant figures appropriately, especially when dealing with scientific notation.

Misconception Examples

  • Entering pH as a concentration instead of a logarithmic value.
  • Forgetting to use the negative sign in the exponent.

Mathematical Derivation and Examples

  • Deriving [H⁺] from pH and vice versa
  • Relating pH, pOH, [H⁺], and [OH⁻]
  • Worked calculation examples
Key Formulas
[H⁺] = 10^(-pH), pH = -log10([H⁺]), pOH = -log10([OH⁻]), [OH⁻] = 10^(-pOH), pH + pOH = 14, [H⁺][OH⁻] = 1e-14.
Example: If pH = 2, then [H⁺] = 10^(-2) = 0.01 mol/L. If [OH⁻] = 1e-10 mol/L, then pOH = 10, pH = 4.

Mathematical Examples

  • Given pH = 5, [H⁺] = 1e-5 mol/L.
  • Given [OH⁻] = 1e-12 mol/L, pOH = 12, pH = 2.