The pH scale and the Measurement of pH Value of a Solution
- pH scale is a set of numbers used to represent the degree of acidity or alkalinity of a solution.
- pH is a measurement of the concentration of hydrogen ions (H+) in the solution.
- pH value greater than 7: alkaline solution
- pH value of exactly 7: neutral solution
- pH value less than 7: acidic solution
- In an acidic solution = higher in the concentration of the H+ ions, the lower the pH value.
- In an alkaline solution = lower in the concentration of the H+ ions, the higher the pH value.
- pH solution can be measured by using universal indicator, pH paper and pH meter.
| pH value | Colour of Universal Indicator |
| 0, 1, 2 | Red |
| 3 | Orange red |
| 4 | Orange |
| 5 | Orange yellow |
| 6 | Yellow |
| 7 | Green |
| 8 | Greenish-blue |
| 9 | Blue |
| 10 | Blue |
| 11 | Bluish-purple |
| 12, 13, 14 | Purple |
