The pH scale is a logarithmic scale used to measure acidity. The pH scale measures how basic or acidic a substance is, and it ranges from 0 to 14. On the pH scale, a pH of 7 is neutral, less than 7 is acidic and higher than 7 is basic.
The pH of any substance indicates the number of hydrogen ions forming in a specific volume of water. Water is neutral; however, when chemicals are added to water, the mixture becomes basic or acidic. An example of an acidic substance is vinegar, while a substance like ammonia is basic. The pH measurements of substances are used in chemical engineering, medicine, nutrition, biology, water purification, chemistry and many other applications.