pH Calculator

Calculate Solution pH and Ion Concentrations

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pH from [H⁺] Calculator

Use this tool to find the pH of a solution when you know its hydrogen ion concentration ([H⁺]). This is a fundamental calculation in chemistry to determine how acidic or basic a solution is.

pH: -

[H⁺] from pH Calculator

If you know the pH of a solution, this calculator will help you find its hydrogen ion concentration ([H⁺]). This is useful for understanding the exact amount of acidity in a solution.

[H⁺]: - mol/L

pH from Ka Calculator (Weak Acids)

This calculator helps you find the pH of a weak acid solution. You'll need the acid dissociation constant (Ka) and the initial concentration of the acid. It's a key calculation for understanding weak acid behavior.

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Understanding pH: The Scale of Acidity and Basicity

What is pH?

pH is a number that tells us how acidic or basic (alkaline) a water-based solution is. It's a very common measurement in chemistry, biology, and everyday life. The pH value is directly related to the concentration of hydrogen ions ([H⁺]) in the solution. The more hydrogen ions, the more acidic the solution.

pH = -log₁₀[H⁺]

[H⁺] = 10⁻ᵖᴴ

The pH Scale Explained

The pH scale typically ranges from 0 to 14, helping us classify solutions:

  • pH less than 7: The solution is acidic. The lower the pH number, the stronger the acid (e.g., battery acid, lemon juice).
  • pH equal to 7: The solution is neutral. Pure water at room temperature has a pH of 7.
  • pH greater than 7: The solution is basic (or alkaline). The higher the pH number, the stronger the base (e.g., baking soda, bleach).
  • Each unit change on the pH scale represents a tenfold change in acidity or basicity. For example, a solution with a pH of 4 is ten times more acidic than a solution with a pH of 5.

Why is pH Important? Real-World Applications

Measuring and controlling pH is critical in many different fields:

  • Chemical Processes: Many industrial chemical reactions require a specific pH to work correctly and efficiently.
  • Biological Systems: The pH of our blood, cells, and even soil is tightly regulated because enzymes and biological processes only function within narrow pH ranges.
  • Environmental Monitoring: Scientists monitor the pH of lakes, rivers, and oceans to check for pollution like acid rain, which can harm aquatic life.
  • Food and Beverage Industry: pH affects the taste, preservation, and safety of food products (e.g., pickling, brewing beer).
  • Agriculture: Soil pH is crucial for plant growth, as different plants thrive in different pH conditions.
  • Water Treatment: Maintaining proper pH in drinking water and wastewater is essential for safety and effective treatment.

Common Solutions and Their pH Values

Here are some everyday examples to help you understand the pH scale:

  • Battery Acid: pH ~0-1 (Very strong acid)
  • Stomach Acid: pH ~1-3 (Helps digest food)
  • Lemon Juice: pH ~2 (Acidic fruit)
  • Coffee: pH ~5 (Slightly acidic)
  • Pure Water: pH 7.0 (Neutral)
  • Human Blood: pH ~7.4 (Slightly basic, tightly regulated)
  • Baking Soda Solution: pH ~9 (Mild base)
  • Ammonia/Bleach: pH ~11-13 (Strong bases, used for cleaning)