pH Scale

• The pH scale measures how acidic or alkaline a substance is.
• The scale ranges from 0 to 14.
• On this scale, 7 is considered neutral. This is the pH of pure water at 25 degrees Celsius.
• Any solution with a pH value below 7 is considered acidic. The lower the pH, the more acidic the solution.
• Any solution with a pH value above 7 is considered basic, or alkaline. The higher the pH, the more alkaline the solution.
• The pH scale is logarithmic, meaning each step represents a ten-fold difference in acidity or alkalinity. For example, a solution with a pH of 4 is ten times more acidic than a solution with a pH of 5.
• The pH scale can be measured using universal indicator paper or a pH probe and metre. The universal indicator will change colour depending on the pH of the solution.
• Human blood has a pH range of around 7.35 to 7.45, making it slightly alkaline.
• Extreme pH values, either very low or very high, can be harmful to life. Many substances, including human tissues, have a specific pH at which they work best.
• Some substances can act as buffers, resisting changes in pH when small amounts of strong acids or bases are added.
• Most plants prefer a soil pH between 6 and 7.5. When the pH level is outside this range, plants may be unable to absorb nutrients properly.