CHEMISTRY IN EVERYDAY LIFE NOTES Upsc Pre GS paper 1 | General Science 

UPSC Preliminary Examination Paper GS-1

Subject: General Science 

Chemistry - Class 11th & 12th 📝 Notes 

CHEMISTRY IN EVERYDAY LIFE IMPORTANT TOPICS 

Drugs and their classification 

Drugs: 

These are chemicals of low molecular mass. These interact with macromolecular targets and produce a biological response. 

Medicine: 

When the biological response is therapeutic and useful, these chemicals are called medicines and are used in diagnosis, prevention and treatment of diseases. 

Chemotherapy: 

Use of chemicals for therapeutic effect is called chemotherapy. 

 Drugs can be classified mainly on criteria outlined as follows: 

(a) On the basis of pharmacological effect 

This classification is based on pharmacological effect of the drugs. It is useful for doctors because it provides them the whole range of drugs available for the treatment of a particular type of problem. For example, analgesics have pain killing effect, antiseptics kill or arrest the growth of microorganisms.

(b) On the basis of drug action

 It is based on the action of a drug on a particular biochemical process. For example, all antihistamines inhibit the action of the compound, histamine which causes inflammation in the body. There are various ways in which action of histamines can be blocked.

(c) On the basis of chemical structure 

It is based on the chemical structure of the drug. Drugs classified in this way share common structural features and often have similar pharmacological activity.

(d) On the basis of molecular targets

 Drugs usually interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. These are called target molecules or drug targets. 

Drugs possessing some common structural features may have the same mechanism of action on targets. The classification based on molecular targets is the most useful classification for medicinal chemists. 

Drug Target Interaction 

Macromolecules of biological origin perform various functions in the body. For example, proteins which perform the role of biological catalysts in the body are called enzymes, those which are crucial to communication system in the body are called receptors. Carrier proteins 

Carry polar molecules across the cell membrane. Nucleic acids have coded genetic information for the cell. Lipids and carbohydrates are structural parts of the cell membrane.

 1. Enzymes as Drug Targets: 

the interaction between a drug and an enzyme, it is important to know how do enzymes catalyse the reaction. In their catalytic activity, enzymes perform two major functions:

 The first function of an enzyme is to hold the substrate for a chemical reaction. Active sites of enzymes hold the substrate molecule in a suitable position, so that it can be attacked by the reagent effectively Substrates bind to the active site of the enzyme through a variety of interactions such as ionic bonding, hydrogen bonding, van der Waals interaction or dipole-dipole interaction 

The second function of an enzyme is to provide functional groups that will attack the substrate and carry out chemical reaction 

2. Drug-enzyme interaction: 

Drugs inhibit any of the above mentioned activities of enzymes. These can block the binding site of the enzyme and prevent the binding of substrate, or can inhibit the catalytic activity of the enzyme. Such drugs are called enzyme inhibitors. 

 Drugs inhibit the attachment of substrate on active site of enzymes in two different ways; 

1. Drugs compete with the natural substrate for their attachment on the active sites of enzymes. Such drugs are called competitive inhibitors. 

2. Some drugs do not bind to the enzyme’s active site. These bind to a different site of enzyme which is called allosteric site. 

 This binding of inhibitor at allosteric site changes the shape of the active site in such a way that substrate cannot recognise it. Receptors as Drug Targets 

Receptors are proteins that are crucial to body’s communication process. Majority of these are embedded in cell membranes. 

Receptor proteins are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane. 

 In the body, message between two neurons and that between neurons to muscles is communicated through certain chemicals. These chemicals, known as chemical messengers are received at the binding sites of receptor proteins. 

 There are a large number of different receptors in the body that interact with different chemical messengers. These receptors show selectivity for one chemical messenger over the other because their binding sites have different shape, structure and amino acid composition 

 Drugs that bind to the receptor site and inhibit its natural function are called antagonists. These are useful when blocking of message is required. There are other types of drugs that mimic the natural messenger by switching on the receptor, these are called agonists. These are useful when there is lack of natural chemical messenger. Therapeutic Action of Different Classes of Drugs Antacids 

Antacids: 

These are medicines that counteract (neutralise) the acid in your stomach to relieve indigestion and heartburn. Sodium hydrogencarbonate or a mixture of aluminium and magnesium hydroxide are used as antacids. Antihistamine Drug 

Histamine: 

It stimulates the secretion of pepsin and hydrochloric acid in the stomach. 

1. Histamine is a potent vasodilator. It contracts the smooth muscles in the bronchi and gut and relaxes other muscles, such as those in the walls of fine blood vessels. 

2. Histamine is also responsible for the nasal congestion associated with common cold and allergic response to pollen. 

3. Synthetic drugs, brompheniramine (Dimetapp) and terfenadine (Seldane), act as antihistamines. 

4. They interfere with the natural action of histamine by competing with histamine for binding sites of the receptor where histamine exerts its effect. 

The drug cimetidine (Tegamet), was designed to prevent the interaction of histamine with the receptors present in the stomach wall. This resulted in the release of a lesser amount of acid. Neurologically Active Drugs 

Neurologically active drugs:

 These affect the message transfer mechanism from nerve to receptor. 

1. Tranquilizers: These are a class of chemical compounds used for the treatment of stress, and mild or even severe mental diseases. 

These relieve anxiety, stress, irritability or excitement by inducing a sense of wellbeing. They form an essential component of sleeping pills. 

 Noradrenaline, Iproniazid and phenelzine are two such drugs. 

 Chlordiazepoxide and meprobamate, are relatively mild tranquilizers suitable for relieving tension. 

 Equanil is used in controlling depression and hypertension. Derivatives of barbituric acid viz., veronal, amytal, nembutal, luminal and seconal constitute an important class of tranquilizers. These derivatives are called barbiturates. Barbiturates are hypnotic, i.e., sleep producing agents. Some other substances used as tranquilizers are valium and serotonin. 

2. Analgesics: It reduces or abolishes pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of the nervous system. These are classified as follows: 

Non-narcotic (non-addictive) analgesics: Aspirin and paracetamol belong to the class of non-narcotic analgesics. 

Aspirin inhibits the synthesis of chemicals known as prostaglandins which stimulate inflammation in the tissue and cause pain. 

 These drugs are effective in relieving skeletal pain such as that due to arthritis. 

 These drugs have many other effects such as reducing fever (antipyretic) and preventing platelet coagulation. Because of its anti blood clotting action, aspirin finds use in prevention of heart attacks. Narcotic analgesics: Morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep. 

In poisonous doses, these produce stupor, coma, convulsions and ultimately death. 

 Morphine narcotics are sometimes referred to as opiates, since they are obtained from the opium poppy. 

These analgesics are chiefly used for the relief of postoperative pain, cardiac pain and pains of terminal cancer, and in childbirth. Antimicrobial Drugs 

Diseases in human beings and animals may be caused by a variety of microorganisms such as bacteria, virus, fungi and other pathogens. 

 Antimicrobial drugs: 

It tends to destroy/prevent development or inhibit the pathogenic action of microbes such as bacteria (antibacterial drugs), fungi (antifungal agents), virus (antiviral agents), or other parasites (antiparasitic drugs) selectively. Antibiotics, antiseptics and disinfectants are antimicrobial drugs

1. Antibiotics: 

These are used as drugs to treat infections because of their low toxicity for humans and animals. Antibiotics refers to a substance produced wholly or partly by chemical synthesis, which in low concentrations inhibits the growth or destroys microorganisms by intervening in their metabolic processes. 

Arsphenamine (salvarsan):

 Paul Ehrlich, a German bacteriologist, developed the medicine, arsphenamine, known as salvarsan. Paul Ehrlich got the Nobel prize for Medicine in 1908 for this discovery. 

Sulphanilamide:

 It is an organic sulfur compound with antibacterial properties. 

Penicillin: 

It is a group of antibacterial drugs that attack a wide range of bacteria. It was discovered by Alexander Fleming in 1929. 

2. Antiseptics and disinfectants: 

These are also the chemicals which either kill or prevent the growth of microorganisms. 

Antiseptics are applied to the living tissues such as wounds, cuts, ulcers and diseased skin surfaces. Examples are furacine, soframycin, etc. 

Commonly used antiseptic, dettol is a mixture of chloroxylenol and terpineol. 

Bithionol (the compound is also called bithional) is added to soaps to impart antiseptic properties. 

Iodine is a powerful antiseptic. Its 2-3 percent solution in alcohol water mixture is known as tincture of iodine. It is applied on wounds. 

 Iodoform is also used as an antiseptic for wounds. 

 Boric acid in dilute aqueous solution is weak antiseptic for eyes. Disinfectants: These are applied to inanimate objects such as floors, drainage system, instruments, etc. 

Chlorine in the concentration of 0.2 to 0.4 ppm in aqueous solution and sulphur dioxide in very low concentrations, are disinfectants. 

Antifertility drugs: 

These are birth control pills essentially containing a mixture of synthetic estrogen and progesterone derivatives. It is known that progesterone suppresses ovulation. 

1. Synthetic progesterone derivatives are more potent than progesterone. 

2. Norethindrone is an example of synthetic progesterone derivative most widely used as an antifertility drug. 

3. The estrogen derivative which is used in combination with progesterone derivative is ethynylestradiol (novestrol). Chemicals in Food ¾ Chemicals are added to food for their preservation, enhancing their appeal, and adding nutritive value in them. 

Main categories of food additives are as follows: 1. (i) Food colours (ii) Flavours and sweeteners (iii) Fat emulsifiers and stabilizing agents (iv) Flour improvers - antistaling agents and bleaches (v) Antioxidants (vi) Preservatives (vii) Nutritional supplements such as minerals, vitamins and amino acids. Artificial Sweetening Agents 

Natural sweeteners, e.g., sucrose adds to calorie intake and therefore many people prefer to use artificial sweeteners. 

1. Ortho-sulphobenzimide:

 It is also called saccharin, is the first popular artificial sweetening agent. 

 It has been used as a sweetening agent ever since it was discovered in 1879. 

 It is about 550 times as sweet as cane sugar. It is excreted from the body in urine unchanged. 

 It appears to be entirely inert and harmless when taken. Its use is of great value to diabetic persons and people who need to control intake of calories. 

2. Aspartame: 

It is the most successful and widely used artificial sweetener. It is roughly 100 times as sweet as cane sugar. 

 It is a methyl ester of dipeptide formed from aspartic acid and phenylalanine. 

Use of aspartame is limited to cold foods and soft drinks because it is unstable at cooking temperature. 

3. Alitame:

 It is a high potency sweetener, although it is more stable than aspartame, the control of sweetness of food is difficult while using it. 

4. Sucralose: 

It is a trichloro derivative of sucrose. Its appearance and taste are like sugar. It is stable at cooking temperature. It does not provide calories. Food Preservatives 

 Food preservatives prevent spoilage of food due to microbial growth. 

The most commonly used preservatives include table salt, sugar, vegetable oils and sodium benzoate, C6H5COONa. 

1. Sodium benzoate is used in limited quantities and is metabolised in the body. 

2. Salts of sorbic acid and propanoic acid are also used as preservatives. Antioxidants in Food 

 Antioxidants are important and necessary food additives. These help in food preservation by retarding the action of oxygen on food. These are more reactive towards oxygen than the food material which they are protecting. 

The two most familiar antioxidants are butylated hydroxytoluene (BHT) and butylated hydroxy anisole (BHA). The addition of BHA to butter increases its shelf life from months to years.

Sulphur dioxide and sulphites are also used as antioxidants. Cleansing Agents 

Soap: 

It is a cleansing and emulsifying agent made usually by action of alkali on fat or fatty acids. 

1. Soaps and synthetic detergents are two types of detergents used as cleansing agents. 

2. These improve cleansing properties of water and help in removal of fats which bind other materials to the fabric or skin. 

3. Soaps used for cleaning purposes are sodium or potassium salts of long chain fatty acids, e.g., stearic, oleic and palmitic acids. 

Only sodium and potassium soaps are soluble in water. 

4. Generally potassium soaps are softer to the skin than sodium soaps. These can be prepared by using potassium hydroxide solution in place of sodium hydroxide. 

Saponification: 

Soaps containing sodium salts are formed by heating fat (i.e., glyceryl ester of fatty acid) with aqueous sodium hydroxide solution. This reaction is known as saponification. 

1. In this reaction, esters of fatty acids are hydrolysed and the soap obtained remains in colloidal form. 

2. It is precipitated from the solution by adding sodium chloride. The solution left after removing the soap contains glycerol, which can be recovered by fractional distillation. Types of soaps 

Basically all soaps are made by boiling fats or oils with suitable soluble hydroxide. Variations are made by using different raw materials. Toilet soaps are prepared by using better grades of fats and oils and care is taken to remove excess alkali. Colour and perfumes are added to make these more attractive. 

 Soaps that float in water are made by beating tiny air bubbles before their hardening. Transparent soaps are made by dissolving the soap in ethanol and then evaporating the excess solvent. In medicated soaps, substances of medicinal value are added. In some soaps, deodorants are added. 

 Shaving soaps contain glycerol to prevent rapid drying. A gum called, rosin is added while making them. It forms sodium rosinate which lathers well. 

 Laundry soaps contain fillers like sodium rosinate, sodium silicate, borax and sodium carbonate Soap chips are made by running a thin sheet of melted soap onto a cool cylinder and scraping off the soaps in small broken pieces. 

Soap granules are dried miniature soap bubbles. Soap powders and scouring soaps contain some soap, a scouring agent (abrasive) such as powdered pumice or finely divided sand, and builders like sodium carbonate and trisodium phosphate. Builders make the soaps act more rapidly. Why do soaps not work in hard water? 

Hard water contains calcium and magnesium ions. These ions form insoluble calcium and magnesium soaps respectively when sodium or potassium soaps are dissolved in hard water. 

 These insoluble soaps separate as scum in water and are useless as a cleansing agent. 

 In fact these are a hindrance to good washing, because the precipitate adheres onto the fibre of the cloth as gummy mass. 

Hair washed with hard water looks dull because of this sticky precipitate. 

 Dye does not absorb evenly on cloth washed with soap using hard water, because of this gummy mass. Synthetic Detergents 

Synthetic detergents: These are cleansing agents which have all the properties of soaps, but which actually do not contain any soap. These can be used both in soft and hard water as they give foam even in hard water. Some of the detergents give foam even in ice cold water. 

Classification: Synthetic detergents are mainly classified into three categories: 

1. Anionic detergents: 

These detergents are the sodium salts of sulfonated long-chain alcohols. 

 These long-chain alcohols are treated with concentrated sulphuric acid to form alkyl hydrogen sulfates. 

 Now, these alkyl hydrogen sulfates are neutralized by treating with alkali and thus form anionic detergents. 

2. Cationic detergents: 

These detergents are the quaternary ammonium salts of amines. In the molecules of these detergents, the cationic part has a long chain of hydrocarbons and a positive charge on the nitrogen atom. 

 One of the important cationic detergents is cetyltrimethylammonium bromide. 3. Non-ionic detergents: These are the detergents that do not contain any kind of ion on them. 

 These detergents are formed by the reaction of stearic acid with polyethylene glycol. 

 These detergents remove grease and oil by micelle formation. Problem associated the use of detergent 

The detergent’s hydrocarbon chain is highly branched, so bacteria cannot degrade this easily. 

Slow degradation of detergents leads to their accumulation. 

Effluents containing such detergents reach the rivers, ponds, etc. These persist in water even after sewage treatment and cause foaming in rivers, ponds and streams and their water gets polluted. 

 These days the branching of the hydrocarbon chain is controlled and kept to the minimum. 

 Unbranched chains can be biodegraded more easily and hence pollution is prevented. 

QUESTIONS LEVEL-1: 

MODERATE 1. 

The ordinary soap is also known as

 (a) Calcium benzoate (b) Sodium benzoate 

(c) Sodium acetate (d) Sodium stearate 

2. The salts used in ordinary soap are 

(a) Sodium (b) Potassium (c) Both A and B (d) Neither 1 nor 2 

3. The soap obtained by the saponification process remains in 

(a) Colloidal form (b) Liquid form (c) Solid form (d) Gaseous form 

4. Which of the following is used as antioxidants 

(a) Butylated hydroxytoluene (BHT) (b) Butylated hydroxy anisole (BHA) (c) Sulphur dioxide 

(d) All of the Above

5. Which of the following is used as Artificial Sweetening Agents? 

(a) Saccharin (b) Aspartame (c) Alitame (d) All of the above 

6. The use of Aspartame is limited to cold foods and soft drinks because

 (a) It is unstable at cooking temperature. (b) It becomes poisonous substance on heating (c) It is less sweet than cane sugar. (d) None of these. 

7. The brompheniramine and terfenadine drug is used as 

(a) Antihistamine (b) Tranquilizers (c) Analgesics (d) Antibiotic 

8. The Equanil drug used as a short term treatment for 

(a) Depression and hypertension (b) Heart attack (c) Constipation (d) Liver failure 

9. Which of the following drugs is an antacid? 

(a) Cimetidine (b) Chlordiazepoxide (c) Meprobamate (d) Noradrenaline

 LEVEL-2: 

ADVANCED 

1. Consider the following statements: 

1. Sucralose is a trichloro derivative of sucrose. 

2. It remains unstable at cooking temperature. 

Which of the statements given above is/are correct?

(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 2. 

Consider the following statements:

 1. Food preservatives prevent spoilage of food due to microbial growth. 

2. Sodium benzoate is used as a food preservative. Which of the statements given above is/are correct? 

(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 

3. Consider the following statements: 

1. The preservatives are inhibitors of biological changes, and the antioxidants are inhibitors of chemical changes. 

2. The preservatives are used in products that contain water, on the other hand, antioxidants are incorporated into products that contain fats Which of the statements given above is/are correct? 

(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 

4. The soaps do not work in hard water because (a) Hard contains calcium and magnesium ions. 

(b) Hard water contains sulphate 

(c) They attract back the removed dirt 

(d) None of the above 

5. Which of the following is/are problem associated with the use of synthetic detergents: 

1. The low degradation of detergents leads to their accumulation. 

2. The bacteria cannot degrade these detergents easily. 

3. It causes foaming in rivers, ponds and streams and their water gets polluted. 

Select the correct answers using code given below: 

(a) 1 only (b) 2 only (c) 1 and 2 only (d) 1, 2 and 3 

6. Consider the following statements: 

1. Detergents are used both in soft and hard water. 

2. They decrease the surface tension of water. 

Which of the statements given above is/are correct? 

(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 

7. Consider the following statements: 

1. Histamine stimulates the secretion of pepsin and hydrochloric acid in the stomach. 

2. Histamine is responsible for the nasal congestion associated with common cold and allergic response to pollen. 

Which of these statements given above is/are correct? 

(a) Only 1 (b) Only 2 (c) Both 1 and 2 (d) Neither 1 nor 2 

LEVEL-3: 

PREVIOUS YEARS 

1. Assertion 

(A): Synthetic detergents can lather well in hard water. 

[UPSC] 

Reason 

(R): Synthetic detergents form soluble calcium and magnesium salts with hard water. 

(a) Both A and R are individually true and R is the correct explanation of A