(a) Mention the pH range within which our body works. Explain how antacids
give relief from acidity. Write the name of one such antacid.
(b) Fresh milk has a pH of 6. How does the pH will change as it turns to curd? Explain your answer.
(c) A milkman adds a very small amount of baking soda to fresh milk. Why does this milk take a longer time to set as curd?
(d) Mention the nature of toothpastes. How do they prevent tooth decay?
Answers
(a) Our stomach has pH equal to 2. Antacids neutralize the excess of acid in our body and gives relief from hyperacidity. Sodium hydrogencarbonate is one of such antacid.
(b) pH will decrease as it turns to curd because curd is acidic due to the presence of lactic acid.
(c) It takes longer time to set as curd as bacteria do not work well in presence of sodium hydrogencarbonate, i.e. fermentation will take place slowly.
(d) Toothpastes are basic in nature. They neutralize the acid formed in mouth which causes tooth decay.
(a) Normal pH range of human body is about 7.35 to 7.45. Usually the body maintains the pH of blood close to 7.40.
→ Antacids reduce acidity by neutralising (counteracting) acid, reducing the acidity in the stomach, and reducing the amount of acid that is refluxed into the esophagus or emptied into the duodenum.
EXAMPLE :- Magnesium hydroxide.
(b) The pH value of milk is 6 since it is acidic in nature. When the milk is converted into curd due to the action of bacteria, lactic acid is formed which is more acidic in nature. Therefore the pH value of the milk is reduced as it turns to curd.
(c) By adding a very small amount of baking soda to fresh milk, the milkman keeps the milk unspoiled for little more time than usual time.
(d) Tootpaste are basic in nature.....they prevent the tooth decay by increasing the ph value of mouth which becomes 5.8 after eating....this much of ph value can slowly led to tooth decay . So, we use toothpastes to bring that ph value greater than 7.
Hope it helps.
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