Calculate Ph of 0.01 M Solution of Sodium Hydroxide

Introduction

The pH of a solution is a measure of its acidity or alkalinity. For a 0.01 M solution of sodium hydroxide, we can calculate the pH using the concentration of the hydroxide ions (OH⁻) produced when NaOH dissolves in water.

Sodium hydroxide is a strong base, meaning it completely dissociates in water according to the equation:

This complete dissociation allows us to directly relate the concentration of NaOH to the concentration of OH⁻ ions.

How to Calculate pH

The pH of a solution can be calculated using the concentration of hydroxide ions with the following formula:

For a 0.01 M solution of NaOH:

1. Determine the concentration of OH⁻ ions: [OH⁻] = [NaOH] = 0.01 M
2. Calculate the logarithm of the hydroxide ion concentration: log[OH⁻] = log(0.01)
3. Add 14 to the logarithm: pH = 14 + log(0.01)

This calculation assumes the solution is at standard temperature and pressure (STP) and that the activity coefficient is 1.

Example Calculation

Let's calculate the pH of a 0.01 M NaOH solution step by step:

1. Given: [NaOH] = 0.01 M
2. Since NaOH is a strong base, [OH⁻] = [NaOH] = 0.01 M
3. Calculate log(0.01): log(0.01) = -2 (since 10⁻² = 0.01)
4. Add 14 to the logarithm: pH = 14 + (-2) = 12

The pH of a 0.01 M NaOH solution is 12.

Interpreting Results

The pH scale ranges from 0 to 14, where:

• pH < 7: Acidic
• pH = 7: Neutral
• pH > 7: Alkaline

A pH of 12 indicates a strongly alkaline solution. This is typical for concentrated NaOH solutions and is commonly used in laboratories for cleaning, neutralization reactions, and as a reagent in various chemical processes.

Understanding the pH of NaOH solutions is crucial in:

• Chemical synthesis
• Water treatment
• Soil pH adjustment
• Biological experiments