HomeScienceChemistryWhat is pH?
Science·2 min·Updated Mar 11, 2026

What is pH?

Potential of Hydrogen

Quick Answer

pH is a scale that measures how acidic or basic a solution is. It ranges from 0 to 14, with lower values indicating acidity, higher values indicating alkalinity, and 7 being neutral.

Overview

The pH scale is a way to quantify the acidity or basicity of a solution. It is based on the concentration of hydrogen ions present in that solution. A solution with a high concentration of hydrogen ions is considered acidic, while one with a low concentration is considered basic or alkaline. For example, lemon juice has a low pH, around 2, making it quite acidic, while baking soda has a high pH of about 9, indicating it is basic. Understanding pH is important in many fields, especially chemistry, biology, and environmental science. In chemistry, pH plays a crucial role in chemical reactions, as many reactions only occur at specific pH levels. In biology, the pH of bodily fluids, like blood, must be tightly regulated to maintain health, as even small deviations can have serious consequences. In everyday life, pH is significant in various applications, such as agriculture, where soil pH affects nutrient availability for plants. Gardeners often test soil pH to ensure it is suitable for growing crops. Additionally, pH is essential in swimming pools, where maintaining the correct pH level helps prevent skin irritation and keeps the water clear.


Frequently Asked Questions

A pH of 7 is considered neutral, meaning the solution is neither acidic nor basic. Pure water is an example of a neutral solution with a pH of 7.
pH can be measured using pH strips, which change color based on the acidity or basicity of a solution, or with a pH meter, which provides a digital reading. Both methods are commonly used in laboratories and various industries.
Maintaining the correct pH in swimming pools is crucial for swimmer comfort and safety. A pH that is too low can cause skin irritation, while a high pH can reduce the effectiveness of chlorine, leading to unsafe water.