For Each of The Following Ph Values Calculate The H3o+

Introduction

The pH scale is a measure of the acidity or basicity of a solution. It's defined as the negative logarithm (base 10) of the hydronium ion (H₃O⁺) concentration. The formula is:

This means that for every increase of 1 in pH units, the concentration of H₃O⁺ decreases by a factor of 10. Conversely, for every decrease of 1 in pH units, the concentration of H₃O⁺ increases by a factor of 10.

The pH Scale

The pH scale ranges from 0 to 14, with:

• pH 7 being neutral (pure water)
• Values below 7 being acidic (increasingly acidic as pH decreases)
• Values above 7 being basic (increasingly basic as pH increases)

Common examples include:

• Battery acid: ~0.8
• Stomach acid: ~1.0-3.0
• Lemon juice: ~2.0
• Vinegar: ~2.4-3.4
• Pure water: 7.0
• Human blood: ~7.35-7.45
• Baking soda solution: ~8.3
• Ammonia solution: ~11.6
• Household bleach: ~12.5

Calculating H3O+ Concentration

To calculate the H₃O⁺ concentration from a given pH value, you can rearrange the pH formula:

Where:

• [H₃O⁺] is the hydronium ion concentration in moles per liter (M)
• pH is the pH value of the solution

This formula shows that the concentration of H₃O⁺ is inversely proportional to the pH value. For example:

• A solution with pH 3 has [H₃O⁺] = 10^-3 M = 0.001 M
• A solution with pH 5 has [H₃O⁺] = 10^-5 M = 0.00001 M
• A solution with pH 8 has [H₃O⁺] = 10^-8 M = 0.00000001 M

Worked Examples

Example 1: pH 2 Solution

Given a solution with pH = 2, calculate the [H₃O⁺].

This means the concentration of H₃O⁺ is 0.01 moles per liter.

Example 2: pH 5 Solution

Given a solution with pH = 5, calculate the [H₃O⁺].

This means the concentration of H₃O⁺ is 0.00001 moles per liter.

Example 3: pH 10 Solution

Given a solution with pH = 10, calculate the [H₃O⁺].

This means the concentration of H₃O⁺ is 0.0000000001 moles per liter.