Question 1 What happens during a honey bee sting.What is its remedy?
Question 2 Under what soil conditions do you think a farmer would treat the soil of his field with quicklime?
Question 3 What happen if there is an excess of acid in the stomach.How can its effects be cured?
Question 4 Explain the pH change as the cause of tooth decay?
Question 5 How can tooth decay caused by the pH change be prevented?
Question 6 How does an antacid work.Name two common antacid?
Question 7 Which chemical is produced in stomach?
Question 8 Which chemical is injected into the skin of a person during an ant’s sting?
Importance of pH in everyday life
1)pH in our digestive system
Our stomach produces hydrochloric acid.This dilute hydrochloric acid helps in digesting our food without harming the stomach.Sometimes excess of acid is produced in the stomach.The excess acid in the stomach causes indigestion which produces pain and irritation.In order to cure indigestion,we can take bases called antacids.Being basic in nature,antacid react with excess acid in the stomach and neutralises it.
The two common antacids are Milk of Magnesia (Magnesium Hydroxide)and Sodium Bicarbonate(Baking soda)
2)pH change as the cause of tooth decay
When we eat food containing sugar,then the bacteria present in our mouth break down the sugar to form acids.This acid lowers the pH in the mouth.Tooth decay starts when the pH of acid formed in the mouth falls below 5.5.This is because then the acid becomes strong enough to attack the enamel of our teeth and corrode it.This sets in tooth decay.The best way to prevent tooth decay is to clean the mouth thoroughly after eating food.
3)Plants and animals are sensitive to pH change
Soil pH and plant growth:Most of the plants grow best when the pH of the soil is close to 7.If the soil is too acidic or basic,the plants grow badly or do not grow at all.The soil pH is also affected by the use of chemical fertilisers in the field.Chemicals can be added to soil to adjust its pH and make it suitable for growing plants.
If the soil is too acidic then it is treated with materials like quicklime or slaked lime.If the soil is too alkaline then alkalinity can be reduced by adding decaying organic matter.
4)Self Defence by animals and plants through chemical warfare
Many animals and plants protect themselves from enemies by injecting painful and irritating acids and bases into their skin.
1)When honey bee stings a person,it injects an acidic liquid into the skin.Rubbing with mild base like baking soda solution on the stung area of the skin gives relief.
2)When a wasp stings,it injects an alkaline liquid into the skin.Then rubbing with a mild acid like vinegar on the stung area of the skin gives relief.