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Calculate The Ph of The Following Solutions 0.10 M Naoh

Reviewed by Calculator Editorial Team

Calculating the pH of a solution is essential in chemistry and biology. This guide explains how to determine the pH of a 0.10 M sodium hydroxide (NaOH) solution using the pH formula and provides a step-by-step calculation.

Introduction

The pH scale measures how acidic or basic a solution is. It ranges from 0 to 14, where values below 7 are acidic, 7 is neutral, and values above 7 are basic. Sodium hydroxide (NaOH) is a strong base that completely dissociates in water, making it ideal for pH calculations.

To calculate the pH of a NaOH solution, we use the pH formula:

pH Formula

pH = -log[H+]

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

For strong bases like NaOH, the concentration of hydroxide ions ([OH-]) equals the concentration of the base. We can use the relationship between [H+] and [OH-] to find the pH.

How to Calculate pH

Step 1: Determine the Concentration of Hydroxide Ions

For a 0.10 M NaOH solution, the concentration of hydroxide ions ([OH-]) is equal to the concentration of NaOH because NaOH completely dissociates in water.

Concentration of Hydroxide Ions

[OH-] = [NaOH] = 0.10 M

Step 2: Calculate the Concentration of Hydrogen Ions

The product of [H+] and [OH-] is equal to the ion product of water (Kw), which is 1.0 × 10-14 at 25°C.

Ion Product of Water

[H+] × [OH-] = Kw = 1.0 × 10-14

Rearranging the equation to solve for [H+]:

Concentration of Hydrogen Ions

[H+] = Kw / [OH-] = (1.0 × 10-14) / 0.10 M = 1.0 × 10-13 M

Step 3: Calculate the pH

Using the pH formula and the concentration of hydrogen ions:

pH Calculation

pH = -log[H+] = -log(1.0 × 10-13) = 13.0

pH of a 0.10 M NaOH Solution

A 0.10 M NaOH solution has a pH of 13.0. This is because NaOH is a strong base that completely dissociates in water, producing a high concentration of hydroxide ions. The resulting low concentration of hydrogen ions gives the solution a high pH.

Key Points

  • NaOH is a strong base that completely dissociates in water.
  • The concentration of hydroxide ions equals the concentration of NaOH.
  • The pH of a strong base solution is always greater than 7.

Worked Example

Let's calculate the pH of a 0.10 M NaOH solution step by step.

Step 1: Determine [OH-]

[OH-] = [NaOH] = 0.10 M

Step 2: Calculate [H+]

[H+] = Kw / [OH-] = (1.0 × 10-14) / 0.10 M = 1.0 × 10-13 M

Step 3: Calculate pH

pH = -log[H+] = -log(1.0 × 10-13) = 13.0

The pH of a 0.10 M NaOH solution is 13.0.

FAQ

What is the pH of a 0.10 M NaOH solution?
The pH of a 0.10 M NaOH solution is 13.0.
Why is the pH of a strong base solution greater than 7?
A strong base solution has a high concentration of hydroxide ions, which lowers the concentration of hydrogen ions and results in a pH greater than 7.
How does the concentration of NaOH affect the pH?
Increasing the concentration of NaOH increases the concentration of hydroxide ions, which further lowers the concentration of hydrogen ions and increases the pH.
What is the ion product of water (Kw)?
The ion product of water (Kw) is the product of the concentrations of hydrogen ions and hydroxide ions in pure water, which is 1.0 × 10-14 at 25°C.
Can the pH of a NaOH solution be calculated using the pH formula?
Yes, the pH of a NaOH solution can be calculated using the pH formula, provided the concentration of hydrogen ions is known or can be determined from the concentration of hydroxide ions.