PH value of a solution measures the acidity and basicity of a solution. It also determines the concentration of hydrogen ions in a solution. PH value is equal to the negative of decimal logarithm of hydrogen ion. The formula for pH is;

pH = - Log[H

The pH value of a solution is measured relative to the standard solutions whose values are fixed. Therefore, pH scale is not absolute. Water is a neutral solution, so its pH value is 7. The pH value of an acid solution is less than 7 and pH value of a base solution is greater than 7.

pH = - Log[H

^{+}] Or pH = Log[H^{+}]-The pH value of a solution is measured relative to the standard solutions whose values are fixed. Therefore, pH scale is not absolute. Water is a neutral solution, so its pH value is 7. The pH value of an acid solution is less than 7 and pH value of a base solution is greater than 7.