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Calculate The Ph and Poh of 0.01 N Hcl Solution

Reviewed by Calculator Editorial Team

This calculator helps you determine the pH and pOH of a 0.01 N (normality) hydrochloric acid (HCl) solution. Understanding these values is essential for chemistry students and professionals working with acid-base solutions.

Introduction

The pH scale measures how acidic or basic a solution is, with values ranging from 0 (most acidic) to 14 (most basic). The pOH value is related to pH through the equation pH + pOH = 14. For a strong acid like HCl, the pH can be calculated directly from its concentration.

Normality (N) is a measure of the concentration of a solution based on the number of equivalents of solute per liter of solution. For HCl, which dissociates completely in water, 1 N solution contains 1 gram equivalent of HCl per liter.

Formula

The pH of a strong acid solution can be calculated using the formula:

pH Formula

pH = -log[H+]

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

For a solution of HCl, the concentration of H+ ions is equal to the normality of the solution because HCl completely dissociates in water.

pOH Formula

pOH = 14 - pH

This relationship holds for all aqueous solutions at 25°C.

Calculation

To calculate the pH and pOH of a 0.01 N HCl solution:

  1. Identify the normality (N) of the HCl solution (0.01 N in this case).
  2. Since HCl is a strong acid, [H+] = N = 0.01 M.
  3. Calculate pH using the formula: pH = -log(0.01).
  4. Calculate pOH using the formula: pOH = 14 - pH.

Note

The calculation assumes the solution is at 25°C and that the activity coefficient is 1. For more precise calculations, activity coefficients should be considered.

Example

Let's calculate the pH and pOH of a 0.01 N HCl solution:

  1. Given: N = 0.01 N (HCl)
  2. [H+] = 0.01 M
  3. pH = -log(0.01) = 2
  4. pOH = 14 - 2 = 12

Therefore, the pH of the solution is 2 and the pOH is 12.

pH and pOH Calculation Results
Solution pH pOH
0.01 N HCl 2 12

FAQ

What is the difference between normality and molarity?

Normality (N) measures the concentration of a solution based on the number of equivalents of solute per liter, while molarity (M) measures the concentration based on the number of moles of solute per liter. For HCl, 1 N = 1 M because it dissociates completely into one equivalent per molecule.

Why is the pH of a 0.01 N HCl solution 2?

The pH is 2 because the concentration of H+ ions is 0.01 M, and -log(0.01) equals 2. This is characteristic of a very acidic solution.

How does temperature affect the pH calculation?

The pH calculation assumes 25°C. At different temperatures, the dissociation of water changes slightly, affecting the pH. For precise work, temperature corrections should be applied.