Chemistry in Everyday Life – Detailed Notes

NEET Chemistry: Chemistry in Everyday Life – Detailed Notes and Practice Questions

Chapter 16: Chemistry in Everyday Life

1. Drugs and Their Classification

  • Drugs (Medicines): Chemicals of low molecular masses (100−500u) which interact with macromolecular targets and produce a biological response. When the biological response is therapeutic and desirable, these chemicals are called medicines.
  • Chemotherapy: The use of chemicals for therapeutic effect.

A. Classification of Drugs:

  1. Based on Pharmacological Effect (Therapeutic Action): Most useful for doctors.
    • Example: Analgesics (pain killers), Antipyretics (reduce fever), Antiseptics (kill microorganisms on living tissues).
  2. Based on Drug Action: Based on the action of a drug on a particular biochemical process.
    • Example: Antihistamines inhibit the action of histamine.
  3. Based on Chemical Structure: Based on chemical structure. Drugs in this class often have similar pharmacological activity.
    • Example: Sulphonamides (antibacterial drugs like sulphamethoxazole).
  4. Based on Molecular Targets: Based on the interaction of drugs with biomolecules like carbohydrates, lipids, proteins, and nucleic acids (macromolecular targets). Most useful classification for medicinal chemists.

B. Drug-Target Interaction:

  • Enzymes, receptors are common drug targets.
  • Enzymes as Drug Targets:
    • Catalytic activity of enzymes:
      • The enzyme’s active site is where the substrate binds.
      • Drugs can block the binding site of the enzyme (competitive inhibitors) or prevent the catalytic activity of the enzyme.
    • Enzyme Inhibitors: Bind to the active site and block substrate binding (competitive) or bind to an allosteric site (non-competitive), changing the active site shape.
  • Receptors as Drug Targets:
    • Receptors: Proteins (macromolecules) that are crucial for communication between various parts of the body. They are embedded in the cell membrane.
    • Binding Site: Proteins that act as receptors have binding sites on the cell membrane, which receive chemical messengers.
    • Agonists: Drugs that mimic the natural messenger and switch on the receptor.
    • Antagonists: Drugs that bind to the receptor site and inhibit its natural function (block the binding of natural messenger). These are useful when blocking a message is required.

2. Therapeutic Action of Different Classes of Drugs

A. Antacids:

  • Drugs that neutralize excess acid in the stomach.
  • Examples: Magnesium hydroxide (Mg(OH)2​), Aluminium hydroxide (Al(OH)3​).
  • Omeprazole, Lansoprazole, Ranitidine (Zantac), Cimetidine (Tagamet): Are more effective than simple antacids as they control the cause of acidity (release of histamine, which stimulates HCl secretion) by interacting with receptors.

B. Antihistamines:

  • Drugs that counteract the action of histamine.
  • Histamine: A potent vasodilator. Causes allergic responses (runny nose, watery eyes, sneezing, itching). Also stimulates the secretion of HCl in the stomach (hence used for acidity control).
  • Examples: Brompheniramine (Dimetapp), Terfenadine (Seldane), Cimetidine, Ranitidine. (Cimetidine and Ranitidine are antihistamines that specifically prevent interaction of histamine with H2 receptors in stomach, thus preventing acid secretion).

C. Neurologically Active Drugs: Act on the nervous system.

  1. Tranquilizers (Psychotherapeutic drugs):
    • Used to treat mental diseases like anxiety, stress, irritability, mild depression. They induce a sense of well-being.
    • Examples:
      • Norepinephrine: A neurotransmitter that plays a role in mood. If levels are low, a person suffers from depression.
      • Antidepressant drugs: Inhibit enzymes that catalyze the degradation of norepinephrine, allowing it to stay longer at the receptor, thus alleviating depression. Example: Iproniazid, Phenelzine.
      • Chlordiazepoxide, Meprobamate, Equanil (meprobamate): Mild tranquilizers for anxiety.
      • Barbiturates (e.g., Veronal, Amytal, Nembutal, Luminal, Seconal): Hypnotics (sleep-inducing agents). Derivatives of barbituric acid.
  2. Analgesics (Pain Killers):
    • Reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination, or paralysis.
    • Non-narcotic (Non-addictive) Analgesics:
      • Examples: Aspirin (acetylsalicylic acid), Paracetamol (acetaminophen).
      • Properties: Anti-inflammatory, antipyretic (fever-reducing). Aspirin is also an anti-blood clotting agent (prevents heart attacks).
      • Side effects of Aspirin: Can cause bleeding, irritating to stomach.
    • Narcotic (Addictive) Analgesics: Opioids (morphine and its derivatives).
      • Examples: Morphine, Codeine, Heroin.
      • Properties: Relieve pain and produce sleep. Used for post-operative pain, cardiac pain, terminal cancer pain.
      • Side effects: Addiction, drowsiness, nausea, constipation, respiratory depression.

D. Antimicrobials:

  • Drugs that kill or inhibit the growth of microorganisms (bacteria, fungi, viruses, other parasites).
  • Antibiotics: Drugs used to cure infections caused by bacteria. (First discovered: Penicillin).
    • Bactericidal (kill bacteria): Examples: Penicillin, Aminoglycosides, Ofloxacin.
    • Bacteriostatic (inhibit growth): Examples: Erythromycin, Tetracycline, Chloramphenicol.
    • Broad Spectrum Antibiotics: Effective against a wide range of gram-positive and gram-negative bacteria. Example: Chloramphenicol, Ampicillin, Amoxicillin, Ofloxacin.
    • Narrow Spectrum Antibiotics: Effective against either gram-positive or gram-negative bacteria. Example: Penicillin G.
    • Limited Spectrum Antibiotics: Effective against a single organism or disease.
  • Antiseptics and Disinfectants: Both prevent the growth of microorganisms or kill them.
    • Antiseptics: Applied to living tissues (wounds, cuts, ulcers, diseased skin surfaces). Examples: Dettol (chloroxylenol + terpineol), Savlon, Bithional (added to soaps), Tincture of Iodine (2-3% iodine in alcohol-water), Boric acid (dilute aqueous solution for eyes).
    • Disinfectants: Applied to inanimate objects (floors, drainage systems, instruments). Examples: Chlorine (0.2−0.4ppm in water for sterilization), Sulphur dioxide.
    • Phenol: A 0.2% solution acts as an antiseptic, while a 1% solution acts as a disinfectant.
  • Antifertility Drugs: Prevent pregnancy (birth control pills).
    • These are synthetic hormonal preparations, usually a mixture of estrogen and progesterone derivatives.
    • Examples: Norethindrone (progesterone derivative), Ethynylestradiol (Novestrol) (estrogen derivative).

3. Chemicals in Food

  • Food Additives: Added to food to preserve it, enhance its appeal, and add nutritive value.
    • Examples: Artificial sweeteners, food preservatives, antioxidants.

A. Artificial Sweetening Agents:

  • Sweeteners that do not add calories to the body. Useful for diabetic patients and calorie-conscious individuals.
  • Examples:
    1. Saccharin: First popular artificial sweetener. 550 times sweeter than cane sugar. Excreted in urine unchanged.
    2. Aspartame: Most successful and widely used. 100 times sweeter than cane sugar. Used in cold foods and soft drinks (unstable at cooking temperature).
    3. Sucralose: Trichlorogalactosucrose. 600 times sweeter than cane sugar. Stable at cooking temperature. No calories.
    4. Alitame: High potency sweetener (2000 times sweeter than cane sugar). Difficult to control sweetness.
    5. Cyclamates: Now banned in many countries due to potential health risks.

B. Food Preservatives:

  • Prevent spoilage of food due to microbial growth.
  • Examples:
    • Table salt, sugar, vegetable oil, sodium benzoate (C6​H5​COONa).
    • Sodium benzoate is used in small amounts (up to 0.1%) in jams, pickles.
    • Salts of sorbic acid and propanoic acid are also used.

C. Antioxidants in Food:

  • Prevent oxidation of food (rancidity of fats and oils).
  • Examples:
    • Butylated Hydroxytoluene (BHT)
    • Butylated Hydroxyanisole (BHA)
    • These are phenolic compounds. Adding them to food containing fats and oils protects them from oxidation.
    • Citric acid, Ascorbic acid (Vitamin C) are also natural antioxidants.

4. Cleansing Agents

A. Soaps:

  • Definition: Sodium or potassium salts of long-chain fatty acids (e.g., stearic acid, oleic acid, palmitic acid).
  • Preparation: Saponification – heating fats or oils (triglycerides) with aqueous NaOH (or KOH).
    • Glycerol is a byproduct.
    • Fat/Oil+NaOH/KOH→Soap+Glycerol
  • Types:
    • Hard soaps: Sodium salts (for laundry).
    • Soft soaps: Potassium salts (for bathing, produce more lather).
    • Transparent soaps: Made by dissolving soap in ethanol and then evaporating the excess solvent.
    • Medicated soaps: Contain antiseptic agents.
    • Shaving soaps: Contain glycerol (to prevent rapid drying) and rosin gum (lathering agent).
  • Limitations: Soaps do not work effectively in hard water.
    • Hard water: Contains calcium (Ca2+) and magnesium (Mg2+) ions.
    • These ions react with soap to form insoluble precipitates (scum), which stick to clothes/skin and make it difficult to form lather.
    • 2C17​H35​COONa (Soap)+Ca2+→(C17​H35​COO)2​Ca↓ (Scum)+2Na+

B. Synthetic Detergents (Syndets):

  • Definition: Cleansing agents that have all the properties of soap but do not form scum with hard water. They are usually sodium salts of sulphonic acids.
  • Advantages: Work effectively in both soft and hard water, and also in acidic solutions.
  • Types:
    1. Anionic Detergents: Large anionic part. Sodium salts of sulphonated long-chain alcohols or hydrocarbons.
      • Examples: Sodium lauryl sulphate (CH3​(CH2​)11​OSO3−​Na+), Sodium dodecylbenzenesulphonate (SDBS).
      • Preparation: Long-chain alcohol Conc.H2​SO4​​ alkyl hydrogen sulphate NaOH​ sodium alkyl sulphate.
      • Uses: Household uses, laundry detergents, toothpastes.
    2. Cationic Detergents: Large cationic part. Quaternary ammonium salts of amines with acetates, chlorides, or bromides.
      • Example: Cetyltrimethylammonium bromide.
      • Properties: Germicidal properties, more expensive.
      • Uses: Hair conditioners.
    3. Non-ionic Detergents: No ions in their structure. Formed by reaction of stearic acid with poly(ethylene glycol).
      • Examples: Detergents used in dishwashing.
      • Mechanism: Do not contain ionic part. Cleansing action is due to hydrogen bonding and micelle formation.
      • Uses: Liquid dishwashing detergents (lather less).
  • Biodegradability of Detergents:
    • Detergents with highly branched hydrocarbon chains are non-biodegradable (microorganisms cannot degrade them easily), leading to pollution (foaming in rivers, lakes).
    • Detergents with straight (unbranched) hydrocarbon chains are biodegradable (easily degraded by microorganisms), reducing environmental pollution. Current detergents are biodegradable.

NEET Chemistry: Chemistry in Everyday Life – Practice Questions

I. Multiple Choice Questions (MCQs)

  1. Which of the following acts as an antacid?
    a) Aspirin
    b) Paracetamol
    c) Omeprazole
    d) Penicillin
  2. Which one of the following is a narcotic analgesic?
    a) Aspirin
    b) Paracetamol
    c) Morphine
    d) Ibuprofen
  3. Iproniazid is used as a:
    a) Antacid
    b) Antihistamine
    c) Antidepressant
    d) Antibiotic
  4. Which among the following is classified as a broad-spectrum antibiotic?
    a) Penicillin G
    b) Chloramphenicol
    c) Ampicillin
    d) Both (b) and (c)
  5. Which substance is used as an antiseptic?
    a) 1% solution of Phenol
    b) 0.2% solution of Phenol
    c) Chlorine (0.2−0.4 ppm)
    d) Sulphur dioxide
  6. Tincture of iodine is:
    a) 2−3% solution of iodine in water
    b) 2−3% solution of iodine in alcohol-water mixture
    c) 2−3% solution of iodine in chloroform
    d) 2−3% solution of iodine in aqueous KI
  7. Which artificial sweetener is not stable at high cooking temperatures?
    a) Saccharin
    b) Aspartame
    c) Sucralose
    d) Alitame
  8. Which compound is commonly added to soaps for antiseptic action?
    a) Bithional
    b) Dettol
    c) Savlon
    d) Tincture of Iodine
  9. Identify the non-ionic detergent from the following:
    a) Sodium lauryl sulphate
    b) Cetyltrimethylammonium bromide
    c) Polyethylene glycol stearate
    d) Sodium dodecylbenzenesulphonate
  10. Which type of detergent is generally non-biodegradable?
    a) Anionic detergents with straight chains
    b) Cationic detergents with straight chains
    c) Detergents with highly branched hydrocarbon chains
    d) Non-ionic detergents
  11. Which chemical stimulates the release of acid in the stomach?
    a) Serotonin
    b) Dopamine
    c) Histamine
    d) Norepinephrine
  12. Which of the following is classified as a hypnotic drug?
    a) Equanil
    b) Meprobamate
    c) Veronal
    d) Chlordiazepoxide
  13. Aspirin is chemically referred to as:
    a) Acetaminophen
    b) Acetylsalicylic acid
    c) Salicylic acid
    d) Methyl salicylate
  14. Norethindrone is an example of which category of drugs?
    a) Antidepressant
    b) Antifertility drug
    c) Antihistamine
    d) Tranquilizer
  15. Which preservative is commonly found in jams and pickles?
    a) Table salt
    b) Sugar
    c) Sodium benzoate
    d) All of the above

II. Assertion-Reason Type Questions

Directions: In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is NOT the correct explanation of A. c) A is true but R is false. d) A is false but R is true.

16. Assertion (A): Cimetidine and Ranitidine are antacids. Reason (R): They prevent the interaction of histamine with receptors present in the stomach wall.

17. Assertion (A): Soaps do not work effectively in hard water. Reason (R): Calcium and magnesium ions in hard water form insoluble precipitates with soap molecules.

18. Assertion (A): Aspirin is used to prevent heart attacks. Reason (R): Aspirin has anti-blood clotting action.

19. Assertion (A): Drugs interacting with biomolecules like proteins are called molecular targets. Reason (R): These biomolecules perform various functions in the body.

20. Assertion (A): Highly branched chain detergents are non-biodegradable. Reason (R): Microorganisms cannot easily degrade highly branched hydrocarbon chains.

III. Short Answer / Conceptual Questions

21. Question: Differentiate between Antiseptics and Disinfectants. Give one example of each.

22. Question: What are artificial sweeteners? Give two reasons why they are used.

23. Question: Explain why non-biodegradable detergents cause environmental problems.

24. Question: What is the basic difference between narcotic and non-narcotic analgesics? Give one example of each.

25. Question: How do antacids like Omeprazole or Ranitidine differ from simple antacids like Mg(OH)2​?

26. Question: Write the chemical reaction for the preparation of soap (saponification). What is the byproduct?

27. Question: What are tranquilizers? Name two types of tranquilizers based on their usage.

28. Question: Explain why aspirin is not always suitable for people with stomach ulcers.

29. Question: Differentiate between bactericidal and bacteriostatic antibiotics with one example each.

30. Question: What are food antioxidants? Give an example and explain their function.

Answers and Explanations

I. Multiple Choice Questions (MCQs) – Answers

1. Answer: c) Omeprazole Explanation: Omeprazole is a proton pump inhibitor, which is a type of antacid that controls acid secretion. Aspirin and Paracetamol are analgesics/antipyretics. Penicillin is an antibiotic.

2. Answer: c) Morphine Explanation: Morphine is a narcotic (addictive) analgesic, belonging to the opioid class, used for severe pain relief. Aspirin, Paracetamol, and Ibuprofen are non-narcotic analgesics.

3. Answer: c) Antidepressant Explanation: Iproniazid is an antidepressant drug that works by inhibiting enzymes that degrade neurotransmitters like norepinephrine, thus elevating mood.

4. Answer: d) Both (b) and (c) Explanation: Chloramphenicol and Ampicillin are both examples of broad-spectrum antibiotics, effective against a wide range of bacteria. Penicillin G is a narrow-spectrum antibiotic.

5. Answer: b) 0.2% solution of Phenol Explanation: A 0.2% solution of phenol acts as an antiseptic, applied to living tissues. A 1% solution of phenol acts as a disinfectant (for inanimate objects). Chlorine and sulphur dioxide are disinfectants.

6. Answer: b) 2−3% solution of iodine in alcohol-water mixture Explanation: Tincture of iodine is an antiseptic solution, typically containing 2-3% iodine dissolved in a mixture of alcohol and water.

7. Answer: b) Aspartame Explanation: Aspartame is unstable at cooking temperatures, which limits its use to cold foods and soft drinks. Saccharin and Sucralose are stable at higher temperatures.

8. Question: a) Bithional Explanation: Bithional is a compound commonly added to soaps to impart antiseptic properties. Dettol and Savlon are mixtures used as antiseptics/disinfectants.

9. Answer: c) Polyethylene glycol stearate Explanation: Non-ionic detergents do not contain any ionic groups. Polyethylene glycol stearate is an example of a non-ionic detergent. Sodium lauryl sulphate and sodium dodecylbenzenesulphonate are anionic. Cetyltrimethylammonium bromide is cationic.

10. Answer: c) Detergents with highly branched hydrocarbon chains Explanation: Detergents with highly branched hydrocarbon chains are non-biodegradable because microorganisms cannot easily metabolize and break down these branched structures, leading to environmental pollution (e.g., foaming in rivers).

11. Answer: c) Histamine Explanation: Histamine is a chemical messenger that stimulates the secretion of hydrochloric acid (HCl) in the stomach. Antacids like Ranitidine and Cimetidine block the action of histamine.

12. Answer: c) Veronal Explanation: Veronal is a derivative of barbituric acid and is classified as a hypnotic, meaning it is sleep-inducing. Equanil, Meprobamate, and Chlordiazepoxide are tranquilizers used for anxiety, not primarily as hypnotics.

13. Answer: b) Acetylsalicylic acid Explanation: Aspirin’s chemical name is acetylsalicylic acid. Paracetamol is chemically acetaminophen.

14. Answer: b) Antifertility drug Explanation: Norethindrone is a synthetic progesterone derivative and is a well-known example of an antifertility drug, used in birth control pills.

15. Answer: c) Sodium benzoate Explanation: While table salt and sugar are also food preservatives, sodium benzoate is specifically mentioned as a common chemical food preservative used in jams and pickles (up to 0.1%).

II. Assertion-Reason Type Questions – Answers

16. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Cimetidine and Ranitidine are antacids in the sense that they reduce stomach acidity. Their mechanism is not direct neutralization but by preventing the interaction of histamine with H2 receptors in the stomach wall, thereby controlling the secretion of acid. So, the Reason correctly explains the Assertion’s function in controlling acidity.

17. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Soaps are sodium or potassium salts of long-chain fatty acids. In hard water, calcium (Ca2+) and magnesium (Mg2+) ions react with the soap to form insoluble calcium and magnesium salts of fatty acids (scum), which precipitates out. This leads to inefficient lathering and cleansing, and scum formation.

18. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Aspirin is known for its anti-platelet or anti-blood clotting action. This property is crucial in preventing blood clot formation, which can lead to heart attacks and strokes. Thus, the Reason correctly explains the Assertion.

19. Answer: b) Both A and R are true but R is NOT the correct explanation of A. Explanation: Assertion (A) is true: biomolecules like proteins (enzymes, receptors) that interact with drugs are indeed called molecular targets. Reason (R) is also true: these biomolecules perform various vital functions in the body. However, the reason doesn’t explain why they are called “molecular targets” (which is due to the drug specifically targeting their function).

20. Answer: a) Both A and R are true and R is the correct explanation of A. Explanation: Detergents with highly branched hydrocarbon chains are indeed non-biodegradable. This is because the enzymes of microorganisms cannot easily attack and degrade the branched structures, leading to their persistence in the environment and causing pollution.

III. Short Answer / Conceptual Questions – Answers

21. Answer:

  • Antiseptics: These are chemical substances that are applied to living tissues (like wounds, cuts, ulcers, diseased skin surfaces) to kill or inhibit the growth of microorganisms. They are relatively mild and do not harm living cells.
    • Example: Dettol (a mixture of chloroxylenol and terpineol), Savlon, Tincture of iodine, diluted boric acid solution (for eyes).
  • Disinfectants: These are chemical substances that are applied to inanimate objects (like floors, drainage systems, instruments, sanitaryware) to kill microorganisms. They are generally much stronger and harsher than antiseptics and are harmful to living tissues.
    • Example: 1% solution of phenol, Chlorine (0.2−0.4ppm in water for sterilization), Sulphur dioxide.
    • (Note: The same chemical can act as an antiseptic or disinfectant depending on its concentration, e.g., phenol).

22. Answer:

  • Artificial sweeteners: These are chemical compounds that are used as sugar substitutes to provide sweetness to food without adding significant calories.
  • Two reasons for their use:
    1. For Diabetic Patients: Artificial sweeteners do not raise blood glucose levels, making them suitable for diabetic individuals who need to restrict their sugar intake.
    2. For Calorie-Conscious Individuals: They provide sweetness without contributing to caloric intake, aiding in weight management. They are used in diet foods and beverages.

23. Answer: Non-biodegradable detergents cause significant environmental problems, primarily water pollution. Explanation: Non-biodegradable detergents typically have highly branched hydrocarbon chains. Microorganisms present in sewage treatment plants and natural water bodies (like rivers and lakes) cannot easily degrade or break down these branched structures. As a result, these detergents persist in water bodies for a long time. Their presence leads to:

  1. Foaming: They cause persistent foaming in rivers and lakes, affecting aquatic life.
  2. Eutrophication: The phosphate builders often used in detergents can act as nutrients for algae, leading to excessive algal growth (algal bloom). This algal bloom consumes dissolved oxygen, harming fish and other aquatic organisms.
  3. Aesthetic Problems: The foam and accumulation of detergents make water bodies unsightly. Due to these issues, detergents with straight hydrocarbon chains (which are biodegradable) are now preferred and widely used.

24. Answer: The basic difference between narcotic and non-narcotic analgesics lies in their mechanism of action, addictive potential, and typical uses:

  • Non-narcotic (Non-addictive) Analgesics:
    • Mechanism: Primarily inhibit the synthesis of prostaglandins (chemicals responsible for pain, fever, and inflammation).
    • Addictive Potential: Not addictive.
    • Uses: Used for general pain relief (headache, muscle pain, dental pain), fever reduction, and anti-inflammatory action.
    • Examples: Aspirin, Paracetamol.
  • Narcotic (Addictive) Analgesics:
    • Mechanism: Act on opioid receptors in the central nervous system and gastrointestinal tract. They mimic the body’s natural pain-relieving chemicals (endorphins).
    • Addictive Potential: Highly addictive and can lead to physical dependence and tolerance.
    • Uses: Used for severe pain (post-operative pain, cardiac pain, terminal cancer pain) and to induce sleep.
    • Examples: Morphine, Codeine, Heroin.

25. Answer: Antacids like Omeprazole or Ranitidine differ significantly from simple antacids like Magnesium hydroxide (Mg(OH)2​) in their mechanism of action:

  • Simple Antacids (e.g., Mg(OH)2​, Al(OH)3​, Sodium bicarbonate):
    • Mechanism: These are basic compounds that work by directly neutralizing the excess hydrochloric acid (HCl) already present in the stomach. They provide immediate, but temporary, relief from acidity.
    • Limitation: They only treat the symptom (excess acid) and not the underlying cause of acid production.
  • Omeprazole or Ranitidine (H2-receptor antagonists / Proton Pump Inhibitors):
    • Mechanism: These drugs do not neutralize acid directly. Instead, they work by reducing or preventing the production of acid by the stomach lining.
      • Ranitidine (Zantac): Is an H2-receptor antagonist. It blocks the binding of histamine (a chemical messenger that stimulates acid secretion) to the H2-receptors present in the stomach wall, thereby inhibiting HCl secretion.
      • Omeprazole: Is a proton pump inhibitor (PPI). It directly inhibits the proton pump (H+/K+-ATPase) in the stomach lining cells, which is responsible for pumping out H+ ions (acid).
    • Advantage: They are more effective and provide longer-lasting relief by controlling the actual production of acid, addressing the cause of acidity rather than just the symptom.

26. Answer: The chemical reaction for the preparation of soap is called saponification. It involves the hydrolysis of an ester (fat or oil, which are triglycerides) with an alkali (like NaOH or KOH) to form soap and glycerol. Chemical Reaction (using a generic fat/oil):

  CH₂-O-CO-R₁
  |
  CH -O-CO-R₂   + 3 NaOH (aq)  Heat  →   CH₂-OH
  |                                        |
  CH₂-O-CO-R₃                             CH -OH   +   R₁-COONa
                                         |               R₂-COONa
                                        CH₂-OH           R₃-COONa
(Fat/Oil - Triglyceride)               (Glycerol)       (Soap - Sodium salts of fatty acids)

Where R1​,R2​,R3​ are long alkyl chains.

Byproduct: The main byproduct of the saponification reaction is Glycerol (also known as propane-1,2,3-triol).

27. Answer:

  • Tranquilizers: These are a class of neurologically active drugs that are used to treat mental diseases and disorders such as anxiety, stress, irritability, excitement, and mild to severe depression. They help to induce a sense of well-being, calm the patient, and reduce anxiety without causing sleep in mild cases.
  • Two types of tranquilizers based on their usage:
    1. Mild Tranquilizers: Used for alleviating anxiety, tension, and mild depression. They have a calming effect without necessarily inducing sleep.
      • Examples: Chlordiazepoxide, Meprobamate, Equanil.
    2. Hypnotics (Sleep-inducing): These are stronger tranquilizers that induce sleep. They are used for insomnia or severe anxiety where sedation is required. Barbiturates fall into this category.
      • Examples: Veronal, Amytal, Nembutal, Luminal, Seconal (all barbiturates).

28. Answer: Aspirin (acetylsalicylic acid) is an effective non-narcotic analgesic and anti-inflammatory drug. However, it is not always suitable for people with stomach ulcers because:

  1. Stomach Irritation: Aspirin is acidic and can directly irritate the lining of the stomach.
  2. Inhibition of Prostaglandins: Aspirin works by inhibiting the synthesis of prostaglandins. While this reduces pain and inflammation, some prostaglandins have a protective role in the stomach lining (e.g., by increasing mucus secretion and blood flow). By inhibiting these protective prostaglandins, aspirin can worsen existing ulcers or even cause new ones by making the stomach lining more vulnerable to acid.
  3. Anti-clotting Effect: Aspirin’s anti-blood clotting action, while beneficial for heart health, can exacerbate bleeding in individuals with ulcers.

29. Answer: Antibiotics can be classified based on their action on bacteria:

  1. Bactericidal Antibiotics: These are antibiotics that kill the bacteria. They directly cause the death of microbial cells.
    • Example: Penicillin (interferes with bacterial cell wall synthesis), Aminoglycosides, Ofloxacin.
  2. Bacteriostatic Antibiotics: These are antibiotics that inhibit the growth or multiplication of bacteria. They do not directly kill the bacteria, but they stop their reproduction, allowing the host’s immune system to clear the infection.
    • Example: Erythromycin, Tetracycline, Chloramphenicol (interfere with bacterial protein synthesis).

30. Question:

  • Food Antioxidants: These are chemical substances that are added to food items to prevent their oxidation, especially fats and oils. Oxidation leads to spoilage, rancidity (unpleasant smell and taste), and loss of nutritional value.
  • Example: Butylated Hydroxyanisole (BHA) or Butylated Hydroxytoluene (BHT). (Others include Ascorbic acid/Vitamin C, Citric acid).
  • Function: Antioxidants act as sacrificial agents. They preferentially react with free radicals (which initiate the oxidation process of fats and oils) before the free radicals can attack the food components. By doing so, they terminate the chain reactions of oxidation, thus protecting the food from degradation and increasing its shelf life. They essentially “scavenge” free radicals.

Leave a Reply