Calculate H+ for Each of The Following Solutions Oh 0.00045

Calculating the pH of a solution when you know the hydroxide ion (OH⁻) concentration is a fundamental chemistry skill. This guide explains the pH calculation formula, provides a calculator for OH⁻ = 0.00045, and includes practical examples to help you understand the relationship between OH⁻ concentration and pH.

Introduction

The pH scale is a measure of the acidity or basicity of a solution. It ranges from 0 to 14, where:

pH 0-6: Acidic solutions
pH 7: Neutral solution (pure water)
pH 8-14: Basic solutions

For solutions where the hydroxide ion (OH⁻) concentration is known, we can calculate the pH using the following relationship:

pH = 14 - pOH

where pOH is calculated from the OH⁻ concentration:

pOH = -log[OH⁻]

This guide will focus on calculating pH for solutions with OH⁻ concentration of 0.00045 M (molar).

pH Calculation Formula

The complete formula for calculating pH from OH⁻ concentration is:

pH = 14 + log[OH⁻]

This formula is derived from the relationship between hydrogen ions (H⁺) and hydroxide ions (OH⁻) in water:

[H⁺][OH⁻] = 10⁻¹⁴

Taking the negative logarithm (base 10) of both sides gives us the pH and pOH relationship.

Step-by-Step Calculation

Identify the OH⁻ concentration in moles per liter (M). In this case, [OH⁻] = 0.00045 M.
Calculate pOH using the formula: pOH = -log[OH⁻].
Calculate pH using the formula: pH = 14 - pOH.

Let's calculate the pH for a solution with OH⁻ = 0.00045 M:

pOH = -log(0.00045) ≈ 3.347

pH = 14 - 3.347 ≈ 10.653

Therefore, a solution with OH⁻ concentration of 0.00045 M has a pH of approximately 10.65.

Worked Examples

Example 1: Basic Solution

Calculate the pH of a solution with [OH⁻] = 0.00045 M.

pOH = -log(0.00045) ≈ 3.347

pH = 14 - 3.347 ≈ 10.653

This is a basic solution with pH 10.65.

Example 2: Comparing Different OH⁻ Concentrations

OH⁻ Concentration (M)	pOH	pH	Solution Type
0.00045	3.347	10.653	Basic
0.0001	4.0	10.0	Basic
0.00001	5.0	9.0	Basic

As the OH⁻ concentration increases, the pH increases, making the solution more basic.

FAQ

What is the relationship between pH and pOH?

The sum of pH and pOH is always 14 in water at 25°C. This is because [H⁺][OH⁻] = 10⁻¹⁴, and taking the negative logarithm gives pH + pOH = 14.

How do I calculate pH from OH⁻ concentration?

First calculate pOH using pOH = -log[OH⁻], then calculate pH using pH = 14 - pOH.

What does a pH of 10.65 indicate about the solution?

A pH of 10.65 indicates a strongly basic solution, as it is significantly above 7.