IMPORTANCE OF pH IN EVERYDAY LIFE

1. pH in our Digestive system: Due to overeating or various reasons , the excess of hydrochloric acid in the stomach causes indigestion which produces pain and irritation.In order to cure indigestion , we can take bases called antacids(means anti-acid). Antacids are  a group of mild bases which have no toxic effectsw on our body. Being basic in nature, antacids react  with excess acid in the stomach and neutralise it. The two common antacids used for curing indigestion due to acidity are : Magnesium hydroxide (Milk of Magnesia) and Sodium hydrogencarbonate (Baking Soda). 2. pH Change as a cause of Tooth Decay: When we eat food, the bacteria present in our mouth breakdown the sugar to form acids(such as lactic acid). This acid lowers the pH in the mouth making it acidic. 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.. M,any tooth pastes contain bases to neutralise the mouth acid (The pH of toothpaste being about 8.0). So using the toothpastes (which are basic) for cleaning the teeth can neutralise the excess acid in mouth a  

Dr. Darshana Bawankule (2020)               (Acids, Bases and Salts)

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IMPORTANCE OF pH IN EVERYDAY LIFE 3.   A. Plants and Animals are Sensitive to pH changes: Most of the plants grow best when the pH of the soil is close to 7. If the soil is too acidic having low pH, then it is treated with materials like quicklime (calcium oxide) or slaked lime (Calcium hydroxide) or chalk (calcium carbonate). If the soil is too alkaline then it can be reduced by adding decaying organic matter (manure or compost) which contains acidic materials. B. pH change and Survival of Animals: The pH plays an important role in the survival of animals, including human beings. The aquatic animals can survive in lake or river water within  a narrow range of pH change. The high acidity of lake water or river water can kill the aquatic animals. Calcium carbonate is often added to acidic lake water to neutralise the acid  that comes from acid rain.  4. Self Defence by Animals and Plants through Chemical Warfare: When a honey-bee stings a person, it injects acidic liquid into the skin. By rubbing  a mild baking soda neutralises the acidic liquid  injected by bee sting. When a wasp sting, it  injects an alkaline liquid into the skin, then by rubbing a mild acid vinegar on the stung area gives relief. An ant sting injects methanoic acid(HCOOH) causing burning pain. When a person touches a leaves of a nettle plant, the stinging hair of nettle leaves inject methanoic acid into the skin as it is acidic in nature.   It can be neutralize by rubbing baking soda or dock plant which grows besides the nettle plant which is basic in nature.

Dr. Darshana Bawankule (2020)               (Acids, Bases and Salts)

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Assignment Questions

1. What is the pH of  a neutral solution ? Ans. The pH of neutral solution is 7. 2. Which is more basic (or more alkaline): a solution of pH=8 or a solution of pH =11? Ans. A solution of pH=11 will be more basic. 3. What colour will universal indicator show if you add it to the following substances? a. Potassium hydroxide, pH =12 b. Soda water, pH =5 c. Sulphuric acid, pH =2 Ans. Potassium hydroxide, pH =12------ Dark purple a. Soda water, pH =5  ------Orange Yellow b. Sulphuric acid, pH =2 -------Red

Dr. DarshanaBawankule (2020)               (Acids, Bases and Salts)

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Question

Que. You have been provided with three test-tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, resp. If you are given only red litmus paper, how will you identify the contents of each tubes? Ans. Put the red litmus paper in all the test tube turn by turn. The sol which turns red litmus to blue will be a basic solution. Now the blue litmus paper formed can now be used to test the acidic solution. The solution which turns blue litmus paper to red will be acidic solution. And the solution which has no effect on any litmus paper will be neutral.  

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Dr. Darshana Bawankule (2020)               (Acids, Bases and Salts)

What are Organic Acids?

• Acids are those chemical substances  which have a sour taste.  Acids change the color of blue litmus to red. • The acids present in plant materials and animals are called Organic acids. These are naturally occurring acids. Eg. Acetic acid or (Ethanoic acid),  Citric acid, Lactic acid, Tartaric acid, Oxalic acid, and Formic acid(or Methanoic acid). • . Acetic acid or (Ethanoic acid)(CH3COOH) found in Vinegar • Citric acid (C6H8O7)present in Citrus fruit such as lemon and oranges • Lactic acid  (C3H6O3)present in sour milk (or curd) • Tartaric acid (C4H6O6)is present in tamarind and unripe grapes • Oxalic acid, (C2H2O4)present in tomatoes • Formic acid(or Methanoic acid)(HCOOH) is present in ant sting. • Organic acids are weak acids.  

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Dr. Darshana Bawankule (2020)