**What is pH value and its importance in everyday life?**

pH value of a solution shows that a particular solution is acidic, alkaline or neutral. pH value has great importance in manufacturing chemicals and in our everyday life. The term pH was first described by Denish biochemist SΦren Peter Lauritz SΦrensen in 1909, pH is an abbreviation for ‘power of hydrogen’ where p is the short form of the German word potenz (meaning power or exponent of H(+) ions) and H is the symbol of hydrogen.

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**Definition of pH: **

pH is defined as the negative log of hydrogen ion concentration of a solution.

Where shows hydrogen ion concentration

As an example concentration of hydrogen in water is

pH = 7

Therefore the pH value of water is 7.

The pH value of water is considered neutral, a pH value less than 7 shows that solution is acidic and pH value greater than 7, the solution is basic.

**pH Scale:**

pH scale is a mixture of several indicators. It is a universal indicator and shows different colors at different concentration of hydrogen ion in a solution. A scale for measuring hydrogen ion concentration in a solution, called pH scale has been developed. On the pH scale, we can measure pH from 0 (very acidic) to 14 (very alkaline).pH should be thought of simply as a number which indicates the acidic or basic nature of the solution. The higher the hydrogen ion concentration, the lower is the pH value. The pH paper is impregnated with several indicators,it is that’s why it is capable to detect the pH value of all material(aq) and thus, known as a universal indicator.

The strength of acids and bases depends on the number of H^{+ }ions and OH^{– }ions produced, respectively. Acid that give rise to more H^{+ }ions are said to be strong acids, and acids that give less H^{+ }ions are said to be weak acids.

Importance of pH in Everyday’s life:

**Plants and animals:** Our body works within the pH range of 7 to 7.5. A living organism can survive only in a narrow range of pH change. When the pH value of rainwater is less than 5.6 then it is known as acid rain. When acid rain flows through the river or lake, it lowers the pH value of water in them and damages aquatic life.

**The pH of the soil:** Plants require a specific pH range for their healthy growth. For increasing productivity, it is advisable for farmers to check the soil of the field, from the pH value of soil we can get which plants or crops is suitable in order to increase the yield.

**Digestive system**: Our stomach produces HCl,it helps us in the digestion of food. HCl maintains the pH value of the stomach in such a way that is compatible with the secretion of enzymes. Extra HCl in our stomach causes pain and irritation that is treated by the use of the base for example milk of magnesia.

**The decay of tooth:** Tooth decay starts when the pH value is lower than 5.5. In the outer surface of the tooth, the enamel exists which is made of calcium phosphate the strongest substance in our body. It is not dissolved in water but when pH value of mouth is bellow 5.5 the calcium phosphate is corroded. It occurs because bacteria generated due to the food particles available between the teeth produces acids after the degradation of sugar and food particles. To prevent this we have to brush the teeth by a toothpaste since the toothpaste is a base it neutralizes the acid produced by the bacteria.

**Self-defense by animals and plants through chemical warfare: Bee** -Sting leaves an acid which causes pain and irritation. The use of mild base like baking soda on the sting area gives relief. Stinging hair of nettle leaves injects methanoic acid causing burning pain.

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