X SAI CHEM - Importance of pH in daily life

Importance of pH in daily life

1. Effect of acid rain

·                     When pH of rain water < 5.6, it is called acid rain. Acid rain flows into the rivers & thus lowers the pH of river water, thus making the survival of aquatic life difficult.

2. Soil pH & plant growth  

·                     Plants require a specific pH range for their healthy growth.

·                     Examples:

Plants	Preferred pH range
Potato	4.5 ─ 6.0
Garlic, Tomato	5.5 ─ 7.5
Onion, Cabbage	6 .0 ─ 7.5

·                     Soil pH can reach as low as 4. The acidic effect can be neutralized by liming the soil by adding Ca(OH)₂, CaCO₃ or CaO.

·                     Soil with excess limestone (alkaline) reaches pH as high as 8.3. So, in order to reduce the alkaline effect, decaying organic matter (acidic in nature) is added.

3.  pH in our digestive system

·                     Our stomach produces dilute hydrochloric acid which helps in the digestion of food. During indigestion the stomach produces too much acid, which causes pain & irritation.

·                     The excessive acids can be neutralized by use of following antacids─

v   Milk of magnesia ─ Mg(OH)₂.

v   Aluminium hydroxide ─ Al(OH)₃

v   Sodium hydrogen carbonate ─ NaHCO₃

4. pH change leads to tooth decay

·                      Tooth decay starts when pH of mouth < 5.5. The hardest substance, tooth enamel (made of calcium phosphate), is corroded when pH < 5.5. Bacteria in mouth produce acids by degradation of sugar & food particles remaining in the mouth after eating. To neutralize excess acid, tooth pastes containing basic ingredients should be used.

5. Self defence by animals & plants through chemical warfare

·                     Stings of bees & ants leaves methanoic acid which causes pain & irritation. Use of a mild base like baking soda on the stung area neutralizes the effect of acid & gives relief.

·                     Effect of stings of wasps containing alkali is neutralized by application of vinegar (ethanoic acid).

·                     Leaves of neetle plant have stinging hair (due to methanoic acid). The effect of acid is neutralized by application of leaves of ‘dock plants’ which grow beside neetle plant.