Calculate The Ph of Each Solution Given The Following
'/%3E%3Ccircle cx='48' cy='39' r='19' fill='%23f2c9a5'/%3E%3Cpath d='M27 35c3-16 39-17 42 2-8-8-27-9-42-2z' fill='%23374151'/%3E%3Cpath d='M21 86c5-24 49-28 56 0z' fill='%232563eb'/%3E%3Ccircle cx='41' cy='41' r='2' fill='%23111827'/%3E%3Ccircle cx='55' cy='41' r='2' fill='%23111827'/%3E%3Cpath d='M42 52c4 3 9 3 13 0' stroke='%2392400e' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E)
Reviewed by Calculator Editorial Team
Calculating the pH of a solution is essential in chemistry, biology, and environmental science. This guide explains how to determine the pH of each solution using the pH formula, provides examples, and answers common questions about the pH scale.
How to Calculate pH
The pH of a solution is a measure of its acidity or alkalinity. It is calculated using the concentration of hydrogen ions (H⁺) in the solution. The pH scale ranges from 0 to 14, where:
- pH 0-6: Acidic solutions
- pH 7: Neutral solution (pure water)
- pH 8-14: Basic (alkaline) solutions
To calculate the pH of a solution, you need to know the concentration of hydrogen ions (H⁺) in moles per liter (M). The pH formula is:
pH = -log[H⁺]
Where [H⁺] is the concentration of hydrogen ions in the solution.
pH Formula
The pH formula is derived from the definition of pH as the negative logarithm of the hydrogen ion concentration. The formula is:
pH = -log[H⁺]
This formula allows you to calculate the pH of a solution if you know the concentration of hydrogen ions. For example, if the concentration of H⁺ ions is 1 × 10⁻⁵ M, the pH would be:
pH = -log(1 × 10⁻⁵) = 5
This means the solution is neutral.
The pH Scale
The pH scale is a logarithmic scale that measures the acidity or alkalinity of a solution. The scale ranges from 0 to 14, with:
- pH 0: Strongly acidic (e.g., battery acid)
- pH 7: Neutral (e.g., pure water)
- pH 14: Strongly alkaline (e.g., lye)
Each whole number change in pH represents a tenfold change in hydrogen ion concentration. For example, a solution with pH 4 has 10 times more hydrogen ions than a solution with pH 5.
Note: The pH scale is logarithmic, so small changes in pH can indicate significant changes in acidity or alkalinity.
Common pH Values
Here are some common pH values for everyday substances:
| Substance | pH | Type |
|---|---|---|
| Lemon juice | 2 | Acidic |
| Vinegar | 2.5 | Acidic |
| Tomato juice | 4 | Acidic |
| Pure water | 7 | Neutral |
| Human blood | 7.4 | Slightly alkaline |
| Baking soda | 8.3 | Alkaline |
| Ammonia | 11 | Alkaline |
These values can help you understand the acidity or alkalinity of common substances.
FAQ
What is the pH formula?
The pH formula is pH = -log[H⁺], where [H⁺] is the concentration of hydrogen ions in the solution.
How do I calculate the pH of a solution?
To calculate the pH of a solution, measure the concentration of hydrogen ions (H⁺) in moles per liter (M) and use the pH formula: pH = -log[H⁺].
What does a pH of 7 mean?
A pH of 7 indicates a neutral solution, such as pure water. Solutions with pH less than 7 are acidic, and solutions with pH greater than 7 are alkaline.
What are common pH values for everyday substances?
Common pH values include lemon juice (pH 2), vinegar (pH 2.5), tomato juice (pH 4), pure water (pH 7), human blood (pH 7.4), baking soda (pH 8.3), and ammonia (pH 11).