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Chemistry in every day life Class - XII

Topic Name : Chemicals in Medicine

Chemicals used in chemotherapy are most commonly classified according to their action. i. Antipyretics The chemicals which bring down the body temperature during fever are known as antipyretics. Some common examples of antipyretics are aspirin, phenacetin and paracetamol.

The most commonly used antipyretic is aspirin. ii. Antimalarials The chemical substances which are used to prevent (or treat) malaria are known antimalarials. Some antimalarials are quinine, chloroquine, paraquine and primaquine. iii. Analgesics The chemical substances used to relieve pain are known as analgesics. Examples of analgesics are brufen, novalgin, aspirin, etc. Certain narcotics such as morphine, marijuana, codine, heroin, etc. are also used as analgesics but they cause unconsciousness and sleep and are also habit forming. Analgesics are classified as follows:

1. Non-narcotic (non-addictive) analgesics – Aspirin and paracetamol belong to the class of non-narcotic analgesics. 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 if its anti blood clotting action, aspirin finds use in prevention of heart attacks.

2. Narcotic analgesics – Morphine, Heroin, Codein 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 child birth.

DAV CENTENARY PUBLIC SCHOOL, PASCHIM ENCLAVE, NEW DELHI-87CHEMISTRY

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iv. Antiseptics and disinfectants The chemical substances used to kill or prevent the growth of micro-organisms in the living tissue are known as antiseptics. They can be safely applied on living tissues such as wounds, cuts, ulcers diseased skin surfaces, etc. They are also used to reduce body odours resulting from bacterial decomposition on the body or in the mouth, so they are added to powders, breath purifiers, deodorants, etc. Some examples of antiseptics are: • Dettol is a mixture of terpeneol and chloroxylenol and is used for cuts, wounds, etc. • Bithional is added to medicated soaps to reduce the odours resulting from bacterial decomposition on the

body. • Tincture iodine, an alcohol-water solution containing 2-3% iodine is used as an antiseptic. • Iodoform (CHI3) is a powerful antiseptic powder which is used for wounds. • Some organic dyes such as gentian violet and methylene blue are also used as antiseptics. • Salol (phenyl salicylate) is used as an internal antiseptic for throat ailments. • Boric acid is used as a mild antiseptic for eye wash. • 0.2% solution of phenol acts as an antiseptic.

Disinfectants are the chemicals used to kill micro-organisms or stop their growth but are harmful when applied to the living tissue. They are used to kill micro-organisms in drains, on tiles, floors, etc. Some examples of disinfectants are: • Chlorine is used at a concentration of 0.2 — 0.4 ppm to make water fit for drinking purpose. • Low concentration of sulphur dioxide is used for sterilizing squashes for preservation. • High concentration of sulphur dioxide (SO2) gas can be used for disinfecting living rooms, which are infected

with disease causing germs. • A solution of cresol in soapy water (called lysol) is used as disinfectant. • 1% solution of phenol acts as a disinfectant.

v. Tranquillisers The drugs which act on the central nervous system and reduce anxiety and mental depression are called tranquillisers. Thus, they are also called psychotherapeutic drugs. They help the patient to control the emotional distress which otherwise interferes with their normal functioning. These drugs induce sleep and hence, are constituents of sleeping pills. They are habit-forming and should be taken on doctor’s advice only. Some examples of transquillriser are equanil, barbituric acid and its derivatives such as veronal, luminal and seconal.

vi. Antidepressants The drugs that cure mental tension are known as antidepressants. For example, tofranil. Tranquillisers relieve while antidepressants cure mental tension. vii. Antibiotics The chemical substances produced by certain microorganism (like bacteria, fungi and moulds) which can inhibit the growth or even destroy the disease causing microbes are known as antibiotics. The first antibiotic produced was penicillin. It was discovered by Alexander Fleming in 1928 from the mould penicillium notatum. Other antibiotics include streptomycin and chloramphenicol. Broad spectrum antibiotics These are the antibiotics which are effective against several types of harmful micro-organisms. Therefore, these are for curing a variety of diseases. The common examples are tetracycline, chloromycetin and chloramphenicol. Narrow spectrum antibiotics Those effective mainly against a specific bacteria are called narrow spectrum antibiotics. If effective against a single organism or disease, they are referred to as limited spectrum antibiotics. Penicillin G has a narrow spectrum.

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ix. Antimicrobials These are the chemical substances used to cure infections due to micro-organisms. The disease in human beings and animals may be caused by a variety of micro-organisms such as bacteria, viruses, etc. the micro-organisms are extremely small organisms which can be seen only with a microscope. These are also called microbes. Any organism which causes disease is called pathogen . The control of microbial diseases can be achieved by the following three ways:

1. by drugs which kill the organism in the body (bactericidal) 2. by drugs which inhibit or arrest the growth of the organism (bacteriostatic) 3. by increasing immunity and resistance to infection of the body (immunity)

x. Antifertility drugs These are the chemical substances used to control the preganancy. These are also called oral contraceptives. The basic aim of antifertility drugs is to prevent conception or fertilization and therefore, these are also known as birth control pills. xi. Antacids Acidic stomach is necessary for good health, but excessive acidity in the stomach can cause discomforts such as acid indigestion, heart burn, irritation or pain of gastric ulcers. The chemical substances which neutralize excess acid in the gastric juices and give relief from acid indigestion, acidity, heart burns and gastric ulcers are called antacids. Thus, antacids remove the excess acid and raise the pH to appropriate level in stomach. Acid gastritis is one of the common ailment associated with digestion. It is caused by excess of HCl in the gastric juice. Baking soda in water is very common antacid. The bases most widely used in antacids are: aluminium hydroxide, magnesium hydroxide, magnesium trisilicate, calcium carbonate, magnesium carbonate, potassium bicarbonate, etc. xii. Antihistamines Antihistamines are chemical substances which diminish or abolish the main actions of histamine released in body and hence prevent the allergic reactions. These drugs are also called antiallergic drugs The common antihistamines drugs are brompheniramine (Dimetapp) and terfenadine (Seldane). Now the question that arises is, “why do above mentioned antihistamines not affect the secretion of acid in stomach?” The reason is that antiallergic and antacid drugs work on different receptors. xiii. Anaesthetics These are the chemical substances which produce general or local insensibility to pains and other sensations. Cocaine, novocaine are local anaesthetics. Chloroform, vinyl ethers, etc. are general anaesthetics. Chemical in food Many chemical are added to food for their preservation and enhancing their appeal. These are called food additives and are:

• flavours and sweeteners • food colours (dyes) • fat emulsifiers and stabilizing agents • flour improvers antistaling agents and bleaches • antioxidants • preservatives • nutritional supplements such as vitamins, minerals and amino acids.

Food preservatives These are the chemical substances which are added to the food materials to prevent their spoilage and to retain their nutritive value for long periods. These preservatives prevent the rancidity of food and inhibit the growth or kill the micro-organisms. The common salt, sugar, oils and spices provide a medium that resists the activity of micro-organisms in food. The preservation of food by adding sufficient amount of salt to it is called salting. It is used for the preservation of raw mango, amla, beans, tamarind, fish, meat, etc. The salt prevents the water from being available for microbial growth. Sugar syrup is used

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for preserving many fruits such as apples, mango, strawberry, carrot, etc. Besides sugar and salts, other substances such as vinegar, oils, spices, citric acid are also used as food preservatives, which are used for pickles, ketchups, jams, squashes, etc. The growth of microbials in food materials can also be prevented by adding certain chemical substances. The most common preservative used is sodium benzoate. Salts of propionic acid, sorbic acid and potassium metabisulphite (source of sulphur dioxide). Certain food preservatives such as butylated hydroxyanisole (BHA) and bytylated hydroxyl toluene (BHT) for edible oils also act as antioxidants. Salts of sorbic acid and propanoic acid are also used as preservatives. Artificial sweetening agents 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. Other artificial sweeteners commercially used in food articles are: Aspartame is the most successful and widely used artificial sweetener. It is roughly 100 times as sweet as cane sugar. It is 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.

Alitame is high potency sweetener, although it is more stable than aspartame, the control of sweetness of food is difficult while using it. Sucrolose is trichloro derivative of sucrose. Its appearance and taste are like sugar. It is stable at cooking temperature. It does not provide calories. Cleansing Agents In this section, we will learn about detergents. Two types of detergents are used as cleansing agents. These are soaps and synthetic detergents. These improve cleansing properties of water. These help in removal of fats which bind other materials to the fabric or skin. Soaps and detergents Detergents Detergents may be described as cleansing agents that are used with water to remove dirt from a surface. A detergent is basically used to remove dirt. Soap has been used as a detergent for more than two thousand years. Soap is made from oils or fats, which are esters of fatty acids or glycerol. Soaps and detergents are sodium salts of different organic acids. For example, sodium stearate, sodium oleate and sodium palmitate are soaps.

CH2 O

O

O C

OC

O

CO

CH

CH2

+ NaOH3

C 17H35

C 17H35

C 17H35

C 17H35COONa3 +

OH

CH

CH2

CH2

OH

OH

Glyceryl ester of stearic acid (fat) Sodium stearate Glycerol

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Saponification The process of making soap by the hydrolysis of fats and oils with alkalies is called saponification. To make soap, mutton fat containing the ester, glyceryl palmitate, is heated with concentrated sodium hydroxide solution. The ester gets hydrolyzed to form sodium palmitate (soap) and glycerol. The soap gets precipitated by the addition of sodium chloride. The soap separates out from the solution in the form of a solid and starts floating on the surface. The soap crust is removed and put into moulds to get soap cakes. The solution left behind is glycerol. Glycerol is used in drugs, cosmetics, explosives and paints. Vegetable oils such as castor oil, cottonseed oil, soyabean oil, linseed oil, coconut oil, palm oil and olive oil are also used while making soaps.

Why do soaps not work in hard water?

If salts of metals (such as bicarbonates, chlorides and sulphates of calcium and magnesium) are present in appreciable amounts, the water is hard. This is because the cations (Ca2+ and Mg2+) present in hard water will react with soap to form insoluble precipitates. Only after all the calcium and magnesium salts are precipitated by soap, will lather be produced. Hence, a large amount of soap will be used up to produce lather. Hence, the water is known as hard water since it does not readily produce lather with soap.

Cleansing action of soap (How does soap work) A soap molecule is made of two components - one part is a hydrocarbon and the other part a - COONa group. Hydrocarbons are water repelling (hydrophobic) while the - COONa groups are ionic and hence, water attracting (hydrophilic). When a dirty cloth is dipped in soap water, the dirt and grease present on the cloth attach themselves to the hydrocarbon component of the soap molecule. The - COONa part attached to water molecules pulls the dirt away from the surface. Removal of dirt, cleans the cloth. Micelle formation of soap When soap is dissolved in water it forms micelles. In a micelle, the soap molecules are arranged radially, with the hydrocarbon directed towards the centre and the water-attracting (hydrophilic) part directed outwards. The dirt and grease particles lying on the surface wetted by soap are thus entrapped by the micelles and removed. Synthetic detergents synthetic detergents 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. As you have already studied, soaps are sodium salts of long chain fatty acids. Now, similar sodium salts of long chain benzene sulphonic acids or sodium salts of long chain alkyl hydrogen sulphates are known as detergents. Similar to soaps, they too have cleansing properties in water, they too have a large non-ionic hydrocarbon group (hydrophobic group) and an ionic group (hydrophilic group). The only difference is that the ionic group is usually a sulphonate group (- SO3Na) rather than a - COONa group (as in case of soaps). Detergents are made from hydrocarbons obtained from coal or petroleum. Synthetic detergents are mainly classified into three categories:

1. anionic detergents: anionic detergents are sodium salts of sulphonated long chain alcohols or hydrocarbons. Alkyl hydrogensulphates formed by treating long chain alcohols with concentrated sulphuric acid are neutralized with alkali to form anionic detergents. Similarly alkyl benzene sulphonic acids with alkali.

CH3(CH2)10CH2OH

H2SO4CH3(CH2)10CH2OSO3H

NaOH(aq)CH3(CH2)10CH2OSO3Na

Lauryl alcohol Lauryl hydrogensulphate Sodium laurylsuphate (Anionic detergent)

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CH3(CH2)11

H2SO4 CH3(CH2)11SO3H

NaOH(aq)

CH3(CH2)11SO3Na

In anionic detergents, the anionic part of the molecule is involved in the cleansing action. Sodium salts of alkylbenzenesulphonates are an important class of anionic detergents. They are mostly used for household work. Anionic detergents are also used in toothpastes. 2. Cationic detergents: Cationic detergents are quarternary ammonium salts of amines with acetates,

chlorides or bromides as anions. Cationic part possess a long hydrocarbon chain and a positive charge on nitrogen atom. Hence, these are called cationic detergents. Cetyltrimetylammonium bromide is a popular cationic detergent and is used in hair conditioners. Cationic detergents have germicidal properties and are expensive, therefore, these are of limited use.

CH3(CH2)15 N CH3

CH3mon

CH3 +

Br_

3. Non – ionic detergents have do not contain any ion in their constitution. One such detergents do not contain any ion in their constitution. One such detergent is formed when stearic acid reacts with polyethyleneglycol. Liquid dishwashing detergents are non-ionic type. Mechanism of cleansing action of this type of detergents is the same as that of soaps. These also remove grease and oil by micelle formation.

CH3(CH2)16COOH + OH(CH2CH2O)nCH2CH2OH

- H2O CH3(CH2)16COO(CH2CH2O)nCH2CH2OH

Stearic acid Polyethyleneglycol

Pollution caused by use of synthetic detergents Widespread use of synthetic detergents on a large scale has created some environmental problems. Some detergents are not easily broken down by micro-organisms present in water bodies. Thus, they tend to persist for a long time rendering the water unfit for aquatic life. For example, detergents containing phosphates can cause rapid growth of algae. This depletes the water bodies of life-giving oxygen needed by fish and other animals. Advantages of detergents over soaps Detergents have replaced soap as a washing agent due to the following advantages they have over soap:

• Synthetic detergents can lather well even in hard water, unlike soaps. • They are more soluble in water than soaps. • They have stronger cleansing action than soaps, even in cold water. • Some detergents can be used even in acidic solutions as compared to soaps.

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Chemistry

XII

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Question 16.1:

Why do we need to classify drugs in different ways?

Answer

The classification of drugs and the reasons for classification are as follows:

(i) On the basis of pharmacological effect:

This classification provides doctors the whole range of drugs available for the treatment of

a particular type of problem. Hence, such a classification is very useful to doctors.

(ii) On the basis of drug action:

This classification is based on the action of a drug on a particular biochemical process.

Thus, this classification is important.

(iii) On the basis of chemical structure:

This classification provides the range of drugs sharing common structural features and

often having similar pharmacological activity.

(iv) On the basis of molecular targets:

This classification provides medicinal chemists the drugs having the same mechanism of

action on targets. Hence, it is the most useful to medicinal chemists.

Question 16.2:

Explain the term target molecules or drug targets as used in medicinal chemistry.

Answer

In medicinal chemistry, drug targets refer to the key molecules involved in certain

metabolic pathways that result in specific diseases. Carbohydrates, proteins, lipids, and

nucleic acids are examples of drug targets.

Drugs are chemical agents designed to inhibit these target molecules by binding with the

active sites of the key molecules.

Question 16.3:

Name the macromolecules that are chosen as drug targets.

Answer

The macromolecules chosen as drug targets are carbohydrates, lipids, proteins, and nucleic

acids. Question 16.4:

Why should not medicines be taken without consulting doctors?

Answer

A medicine can bind to more than one receptor site. Thus, a medicine may be toxic for

some receptor sites. Further, in most cases, medicines cause harmful effects when taken

in higher doses than recommended. As a result, medicines may be poisonous in such

cases. Hence, medicines should not be taken without consulting doctors.

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Question 16.5:

Define the term chemotherapy.

Answer

The use of chemicals for therapeutic effect is called chemotherapy. For example: the use

of chemicals in the diagnosis, prevention, and treatment of diseases

Question 16.6:

Which forces are involved in holding the drugs to the active site of enzymes?

Answer

Either of the following forces can be involved in holding drugs to the active sites of

enzymes.

(i) Ionic bonding

(ii) Hydrogen bonding

(iii) Dipole − dipole interaction

(iv) van der Waals force

Question 16.7:

While antacids and antiallergic drugs interfere with the function of histamines, why do

these not interfere with the function of each other?

Answer

Specific drugs affect particular receptors. Antacids and anti-allergic drugs work on different

receptors. This is the reason why antacids and anti-allergic drugs do not interfere with

each other’s functions, but interfere with the functions of histamines.

Question 16.8:

Low level of noradrenaline is the cause of depression. What types of drugs are needed to

cure this problem? Name two drugs.

Answer

Anti-depressant drugs are needed to counteract the effect of depression. These drugs

inhibit enzymes catalysing the degradation of the neurotransmitter, noradrenaline. As a

result, the important neurotransmitter is slowly metabolised and then it can activate its

receptor for longer periods of time.

Two anti-depressant drugs are:

(i) Iproniazid

(ii) Phenelzine

Question 16.9:

What is meant by the term ‘broad spectrum antibiotics’? Explain.

Answer

Antibiotics that are effective against a wide range of gram-positive and gram-negative

bacteria are known as broad spectrum antibiotics. Chloramphenicol is a broad spectrum

antibiotic.

It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, meningitis,

and certain forms of urinary infections. Two other broad spectrum antibiotics are

vancomycin and ofloxacin. Ampicillin and amoxicillin −synthetically modified from penicillin

− are also broad spectrum antibiotics.

Question 16.10:

How do antiseptics differ from disinfectants? Give one example of each.

Answer

Antiseptics and disinfectants are effective against micro-organisms. However, antiseptics

are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces,

while disinfectants are applied to inanimate objects such as floors, drainage system,

instruments, etc. Disinfectants are harmful to the living tissues.

Iodine is an example of a strong antiseptic. Tincture of iodine (2 − 3 percent of solution of

iodine in alcohol − water mixture) is applied to wounds. 1 percent solution of phenol is

used as a disinfectant.

Question 16.11:

Why are cimetidine and ranitidine better antacids than sodium hydrogen carbonate or

magnesium or aluminium hydroxide?

Answer

Antacids such as sodium hydrogen carbonate, magnesium hydroxide, and aluminium

hydroxide work by neutralising the excess hydrochloric acid present in the stomach.

However, the root cause for the release of excess acid remains untreated.

Cimetidine and rantidine are better antacids as they control the root cause of acidity. These

drugs prevent the interaction of histamine with the receptors present in the stomach walls.

Consequently, there is a decrease in the amount of acid released by the stomach. This is

why cimetidine and rantidine are better antacids than sodium hydrogen carbonate,

magnesium hydroxide, and aluminium hydroxide.

Question 16.12:

Name a substance which can be used as an antiseptic as well as disinfectant.

Answer

Phenol can be used as an antiseptic as well as a disinfectant. 0.2 percent solution of phenol

is used as an antiseptic, while 1 per cent of its solution is used as a disinfectant.

Question 16.13:

What are the main constituents of dettol?

Answer

The main constituents of dettol are chloroxylenol and α-terpineol.

Question 16.14:

What is tincture of iodine? What is its use?

Answer

Tincture of iodine is a 2 − 3 percent solution of iodine in alcohol − water mixture. It is

applied to wounds as an antiseptic.

Question 16.15:

What are food preservatives?

Answer

Food preservatives are chemicals that prevent food from spoilage due to microbial growth.

Table salt, sugar, vegetable oil, sodium benzoate (C6H3COONa), and salts of propanoic

acid are some examples of food preservatives.

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Question 16.16:

Why is use of aspartame limited to cold foods and drinks?

Answer Aspartame becomes unstable at cooking temperature. This is the reason why its use is

limited to cold foods and drinks.

Question 16.17:

What are artificial sweetening agents? Give two examples.

Answer

Artificial sweetening agents are chemicals that sweeten food. However, unlike natural

sweeteners, they do not add calories to our body. They do not harm the human body.

Some artificial sweeteners are aspartame, saccharin, sucrolose, and alitame.

Question 16.18:

Name a sweetening agent used in the preparation of sweets for a diabetic patient.

Answer

Artificial sweetening agents such as saccharin, alitame, and aspartame can be used in

preparing sweets for diabetic patients.

Question 16.19:

What problem arises in using alitame as artificial sweetener?

Answer

Alitame is a high potency sweetener. It is difficult to control the sweetness of food while

using alitame as an artificial sweetener.

Question 16.20:

How are synthetic detergents better than soap?

Answer

Soaps work in soft water. However, they are not effective in hard water. In contrast,

synthetic detergents work both in soft water and hard water.

Question 16.21:

Explain the following terms with suitable examples

(i) Cationic detergents

(ii) Anionic detergents and

(iii) Non-ionic detergents

Answer

(i) Cationic detergent

Cationic detergents are quaternary ammonium salts of acetates, chlorides, or bromides.

These are called cationic detergents because the cationic part of these detergents contains

a long hydrocarbon chain and a positive charge on the N atom.

For example: cetyltrimethylammonium bromide

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(ii) Anionic detergents

Anionic detergents are of two types:

1.Sodium alkyl sulphates: These detergents are sodium salts of long chain alcohols. They

are prepared by first treating these alcohols with concentrated sulphuric acid and then

with sodium hydroxide. Examples of these detergents include sodium lauryl sulphate

(C11H23CH2OSO3−Na+) and sodium stearyl sulphate (C17H35CH2OSO3

−Na+).

2.Sodium alkylbenzenesulphonates: These detergents are sodium salts of long chain

alkylbenzenesulphonic acids. They are prepared by Friedel-Crafts alkylation of benzene

with long chain alkyl halides or alkenes. The obtained product is first treated with

concentrated sulphuric acid and then with sodium hydroxide. Sodium 4-(1-dodecy)

benzenesulphonate (SDS) is an example of anionic detergents.

(iii) Non-ionic detergents

Molecules of these detergents do not contain any ions. These detergents are esters of

alcohols having high molecular mass. They are obtained by reacting polyethylene glycol

and stearic acid.

Question 16.22:

What are biodegradable and non-biodegradable detergents? Give one example of each.

Answer

Detergents that can be degraded by bacteria are called biodegradable detergents. Such

detergents have straight hydrocarbon chains. For example: sodium lauryl sulphate

Detergents that cannot be degraded by bacteria are called non-biodegradable detergents.

Such detergents have highly-branched hydrocarbon chains. For example:

sodium -4- (1, 3, 5, 7- tetra methyl octyl) benzene sulphonate

Question 16.23:

Why do soaps not work in hard water?

Answer

Soaps are sodium or potassium salts of long-chain fatty acids. Hard water contains calcium

and magnesium ions. When soaps are dissolved in hard water, these ions displace sodium

or potassium from their salts and form insoluble calcium or magnesium salts of fatty acids.

These insoluble salts separate as scum.

This is the reason why soaps do not work in hard water.

Question 16.24:

Can you use soaps and synthetic detergents to check the hardness of water?

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Answer

Soaps get precipitated in hard water, but not in soft water. Therefore, soaps can be used

for checking the hardness of water.

However, synthetic detergents do not get precipitated either in hard water or in soft water.

Therefore, synthetic detergents cannot be used for checking the hardness of water.

Question 16.25:

Explain the cleansing action of soaps.

Answer

Soap molecules form micelles around an oil droplet (dirt) in such a way that the

hydrophobic parts of the stearate ions attach themselves to the oil droplet and the

hydrophilic parts project outside the oil droplet. Due to the polar nature of the hydrophilic

parts, the stearate ions (along with the dirt) are pulled into water, thereby removing the

dirt from the cloth.

Question 16.26:

If water contains dissolved calcium hydrogen carbonate, out of soaps and synthetic

detergents which one will you use for cleaning clothes?

Answer

Synthetic detergents are preferred for cleaning clothes. When soaps are dissolved in water

containing calcium ions, these ions form insoluble salts that are of no further use. However,

when synthetic detergents are dissolved in water containing calcium ions, these ions form

soluble salts that act as cleansing agents.

Question 16.27:

Label the hydrophilic and hydrophobic parts in the following compounds.

(i) (ii)

(iii)

Answer

(i)

(ii)

(iii)

Chemistry

XII

Intext Questions

Question 16.1:

Sleeping pills are recommended by doctors to the patients suffering from sleeplessness

but it is not advisable to take its doses without consultation with the doctor, Why?

Answer

Most drugs when taken in doses higher than recommended may cause harmful effects and

sometimes, may even lead to death. Hence, a doctor should always be consulted before

taking any medicine.

Question 16.2:

With reference to which classification has the statement, ‘ranitidine is an antacid” been

given?

Answer

The given statement refers to the classification of pharmacological effects of the drug. This

is because any drug that is used to counteract the effects of excess acid in the stomach is

called an antacid.

Question 16.3:

Why do we require artificial sweetening agents?

Answer

A large number of people are suffering from diseases such as diabetes and obesity. These

people cannot take normal sugar i.e., sucrose as it is harmful for them. Therefore, artificial

sweetening agents that do not add to the calorie intake of a person are required. Saccharin,

aspartame, and alitame are a few examples of artificial sweeteners.

Question 16.4:

Write the chemical equation for preparing sodium soap from glyceryl oleate and glyceryl

palmitate. Structural formulae of these compounds are given below.

(i)

(ii)

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Answer

(i)

(ii)

Question 16.5:

Following type of nom-ionic detergents are present in liquid detergents, emulsifying agents

and wetting agents. Label the hydrophilic and hydrophobic parts in the molecule.

Identify the functional group (s) present in the molecule.

Answer

Functional groups present in the molecule are:

(i) Ether, and

(ii) primary alcoholic group

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