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Calculate The Ph of 0.1 M Naoh Solution

Reviewed by Calculator Editorial Team

Calculating the pH of a 0.1 M NaOH solution is essential for chemistry students and professionals working with strong bases. This guide provides a step-by-step method to determine the pH using the Henderson-Hasselbalch equation and includes a practical calculator for quick results.

Introduction

The pH of a solution is a measure of its acidity or alkalinity. For strong bases like sodium hydroxide (NaOH), the pH can be calculated using the concentration of the hydroxide ions (OH⁻). A 0.1 M NaOH solution is a strong base, meaning it completely dissociates in water to produce hydroxide ions.

Understanding how to calculate the pH of a NaOH solution is crucial for various chemical applications, including titrations, buffer solutions, and environmental chemistry.

How to Calculate pH

The pH of a strong base solution can be determined using the following steps:

  1. Determine the concentration of hydroxide ions (OH⁻) in the solution.
  2. Calculate the concentration of hydrogen ions (H⁺) using the relationship between H⁺ and OH⁻ in water.
  3. Use the pH formula to convert the hydrogen ion concentration to pH.

Formula: pH = -log[H⁺]

For a strong base solution, [H⁺] = 10-14 / [OH⁻]

For a 0.1 M NaOH solution:

  1. [OH⁻] = 0.1 M (since NaOH completely dissociates)
  2. [H⁺] = 10-14 / 0.1 = 10-13 M
  3. pH = -log(10-13) = 13

Example Calculation

Let's calculate the pH of a 0.1 M NaOH solution step by step.

  1. Given: [NaOH] = 0.1 M
  2. Since NaOH is a strong base, it completely dissociates in water:
    NaOH → Na⁺ + OH⁻
    Therefore, [OH⁻] = 0.1 M
  3. In water, the product of [H⁺] and [OH⁻] is 10-14:
    [H⁺] × [OH⁻] = 10-14
    Substituting [OH⁻] = 0.1 M:
    [H⁺] = 10-14 / 0.1 = 10-13 M
  4. Now, calculate the pH using the formula:
    pH = -log[H⁺] = -log(10-13) = 13

The pH of a 0.1 M NaOH solution is 13, indicating a strongly alkaline solution.

Interpreting Results

The pH scale ranges from 0 to 14, where:

  • pH < 7: Acidic
  • pH = 7: Neutral
  • pH > 7: Alkaline (basic)

A pH of 13 for a 0.1 M NaOH solution confirms it is a very strong base. This means the solution is highly alkaline and can neutralize acids effectively.

Note: The pH calculation assumes the solution is at 25°C and that NaOH is a strong base. For more accurate results, temperature and other factors should be considered.

Frequently Asked Questions

What is the pH of a 0.1 M NaOH solution?

The pH of a 0.1 M NaOH solution is 13, indicating a strongly alkaline solution.

How do you calculate the pH of a strong base?

For a strong base like NaOH, you first determine the concentration of hydroxide ions (OH⁻), then calculate the hydrogen ion concentration (H⁺) using the relationship [H⁺] = 10-14 / [OH⁻], and finally use the pH formula pH = -log[H⁺].

Why is the pH of a 0.1 M NaOH solution 13?

The pH is 13 because the concentration of hydroxide ions (OH⁻) is 0.1 M, leading to a hydrogen ion concentration of 10-13 M, which corresponds to pH 13.

Can the pH of a NaOH solution be higher than 13?

No, the pH of a NaOH solution cannot exceed 14, which is the maximum pH value on the pH scale. A 0.1 M NaOH solution reaches the maximum possible pH of 13, indicating complete dissociation and strong alkalinity.