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Calculate Ph of 0.02m Hno3 Solution

Reviewed by Calculator Editorial Team

This calculator helps you determine the pH of a 0.02M nitric acid (HNO₃) solution. Nitric acid is a strong monoprotic acid that completely dissociates in water, making it ideal for pH calculations. Understanding the pH of an HNO₃ solution is essential in chemistry, environmental science, and industrial applications.

Introduction

The pH of a solution is a measure of its acidity or basicity, defined as the negative logarithm of the hydrogen ion concentration. For strong acids like HNO₃, the pH can be calculated directly from the concentration using the formula:

pH = -log₁₀[H⁺]

Where [H⁺] is the concentration of hydrogen ions in moles per liter (M).

For a 0.02M HNO₃ solution, the concentration of H⁺ ions is equal to the concentration of the acid because it fully dissociates in water. This means we can directly use the acid concentration to calculate the pH.

How to Calculate pH

To calculate the pH of a 0.02M HNO₃ solution:

  1. Identify the concentration of HNO₃ in moles per liter (M). In this case, it's 0.02M.
  2. Since HNO₃ is a strong acid, the concentration of H⁺ ions is equal to the concentration of HNO₃.
  3. Use the pH formula: pH = -log₁₀[H⁺].
  4. Plug in the values and calculate the result.

Note: For weak acids or bases, additional calculations are needed to account for dissociation percentages. This calculator assumes complete dissociation for strong acids.

Example Calculation

Let's calculate the pH of a 0.02M HNO₃ solution step by step:

Given: [HNO₃] = 0.02M

Since HNO₃ is strong acid: [H⁺] = [HNO₃] = 0.02M

pH = -log₁₀[H⁺] = -log₁₀(0.02)

Calculation: pH = -(-1.6990) = 1.6990

Final pH: 1.699 (rounded to 3 decimal places)

This means the solution is highly acidic with a pH of approximately 1.7.

Interpreting Results

The pH scale ranges from 0 to 14, where:

  • pH < 7: Acidic solution
  • pH = 7: Neutral solution
  • pH > 7: Basic solution

A pH of 1.7 indicates a very acidic solution. This is characteristic of strong mineral acids like HNO₃, which can cause tissue damage and should be handled with appropriate safety precautions.

Safety Note: Concentrated nitric acid is highly corrosive and can cause severe burns. Always handle with proper protective equipment and in a well-ventilated area.

Frequently Asked Questions

What is the pH of a 0.02M HNO₃ solution?
The pH of a 0.02M HNO₃ solution is approximately 1.7, indicating a highly acidic solution.
Why does HNO₃ fully dissociate in water?
HNO₃ is a strong acid, meaning it completely dissociates into H⁺ and NO₃⁻ ions in aqueous solution, allowing us to directly use the acid concentration for pH calculations.
How does the concentration of HNO₃ affect the pH?
For strong acids, the pH decreases logarithmically with increasing concentration. Doubling the concentration from 0.02M to 0.04M would decrease the pH by 1 unit (from 1.7 to 0.7).
Can this calculator be used for other strong acids?
Yes, this method applies to any strong monoprotic acid (like HCl, HBr, or HI) where the concentration of H⁺ equals the acid concentration.