The pH scale is a measure of the acidity or alkalinity (basicity) of a solution. It quantifies the concentration of hydrogen ions (H+) in the solution. The scale ranges from 0 to 14, with 7 being neutral.
Acidity and alkalinity are determined by the concentration of hydrogen ions in a solution. The more hydrogen ions present, the more acidic the solution becomes. Conversely, the fewer hydrogen ions, the more alkaline or basic the solution is.
On the pH scale, values below 7 indicate acidity, with lower numbers indicating stronger acidity. A pH of 7 is considered neutral, meaning the concentration of hydrogen ions is equal to the concentration of hydroxide ions (OH-) in the solution. Values above 7 indicate alkalinity, with higher numbers indicating greater alkalinity.
The pH scale is logarithmic, meaning that each unit represents a tenfold difference in acidity or alkalinity. For example, a solution with a pH of 3 is ten times more acidic than a solution with a pH of 4.
The pH of a solution is determined using a pH meter or pH indicator paper. pH meters are electronic devices that measure the electrical potential difference between a reference electrode and a pH-sensitive glass electrode immersed in the solution. The difference in potential is converted into pH readings.
pH indicator papers are strips of paper coated with a pH-sensitive dye. When the paper comes into contact with a solution, it changes color according to the pH of the solution. By comparing the color change to a color chart, the approximate pH of the solution can be determined.
In summary, the pH scale measures the concentration of hydrogen ions in a solution to determine its acidity or alkalinity. Lower pH values indicate greater acidity, while higher pH values indicate greater alkalinity.