Calculate Ph of 0.1 M Naoh Solution

Sodium hydroxide (NaOH) is a strong base that completely dissociates in water to form hydroxide ions (OH⁻). This calculator determines the pH of a 0.1 molar NaOH solution using the standard pH calculation for strong bases.

Introduction

The pH of a solution measures its acidity or alkalinity on a scale from 0 to 14. For strong bases like NaOH, the pH can be calculated directly from the concentration of hydroxide ions. A 0.1 M NaOH solution means there are 0.1 moles of NaOH per liter of solution.

When NaOH dissolves in water, it dissociates completely according to the equation:

NaOH(aq) → Na⁺(aq) + OH⁻(aq)

This complete dissociation means the concentration of hydroxide ions ([OH⁻]) is equal to the concentration of NaOH.

pH Calculation

The pH of a strong base solution is calculated using the hydroxide ion concentration and the definition of pH:

pH = 14 - pOH

Where pOH is calculated from the hydroxide ion concentration:

pOH = -log[OH⁻]

For a 0.1 M NaOH solution:

Determine [OH⁻] = [NaOH] = 0.1 M
Calculate pOH = -log(0.1) = 1.0
Calculate pH = 14 - pOH = 14 - 1.0 = 13.0

Therefore, a 0.1 M NaOH solution has a pH of 13.0.

Note: This calculation assumes the solution is dilute and the activity coefficient is 1. For more concentrated solutions, activity corrections may be needed.

Worked Examples

Example 1: 0.1 M NaOH Solution

Given:

Concentration of NaOH = 0.1 M

Calculation:

[OH⁻] = 0.1 M
pOH = -log(0.1) = 1.0
pH = 14 - 1.0 = 13.0

Result: The pH is 13.0.

Example 2: 0.01 M NaOH Solution

Given:

Concentration of NaOH = 0.01 M

Calculation:

[OH⁻] = 0.01 M
pOH = -log(0.01) = 2.0
pH = 14 - 2.0 = 12.0

Result: The pH is 12.0.

FAQ

What is the pH of a 0.1 M NaOH solution?: The pH of a 0.1 M NaOH solution is 13.0, calculated using the hydroxide ion concentration and the pH definition for strong bases.
Why is the pH of a strong base solution calculated differently than a weak base?: Strong bases like NaOH completely dissociate in water, so their hydroxide ion concentration is equal to their molar concentration. Weak bases only partially dissociate, requiring equilibrium calculations.
Can I use this calculator for other strong base solutions?: Yes, this calculator works for any strong base solution by entering the molar concentration of the base.
What factors affect the pH of a NaOH solution?: The pH depends on the concentration of NaOH and the temperature of the solution. Higher concentrations result in higher pH values.