- Books Name
- Chemistry Class 10 NCERT based
- Publication
- Grow Career Publication
- Course
- CBSE Class 10
- Subject
- Chemistry
Universal indicator
A universal indicator has a pH range from 0 to 14 that indicates the acidity or alkalinity of a solution.
A neutral solution has pH=7
pH
pH=−log10[H+]
In pure water, [H+]=[OH−]=10−7 mol/L. Hence, the pH of pure water is 7.
The pH scale ranges from 0 to 14.
If pH < 7 → acidic solution
If pH > 7→ basic solution
Importance of pH in everyday life
1. pH sensitivity of plants and animals
Plants and animals are sensitive to pH. Crucial life processes such as digestion of food, functions of enzymes and hormones happen at a certain pH value.
2. pH of a soil
The pH of a soil optimal for the growth of plants or crops is 6.5 to 7.0.
3. pH in the digestive system
The process of digestion happens at a specific pH in our stomach which is 1.5 to 4.
The pH of the interaction of enzymes, while food is being digested, is influenced by HCl in our stomach.
4. pH in tooth decay
Tooth decay happens when the teeth are exposed to an acidic environment of pH 5.5 and below.
5. pH of self-defence by animals and plants
Acidic substances are used by animals and plants as a self-defence mechanism. For example, bee and plants like nettle secrete a highly acidic substance for self-defence. These secreted acidic substances have a specific pH.