NCERT Solutions for Class 12 Chemistry Chapter 16 Chemistry in Every Day Life are part of NCERT Solutions for Class 12 Chemistry. Here we have given NCERT Solutions for Class 12 Chemistry Chapter 16 Chemistry in Every Day Life.
|Chapter Name||Chemistry in Every Day Life|
|Number of Questions Solved||37|
NCERT Solutions for Class 12 Chemistry Chapter 16 Chemistry in Every Day Life
NCERT INTEXT QUESTIONS
Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take their doses without consultation with the doctor. Why ?
Sleeping pills contain drugs which may be tranquilizers or antidepressants. They affect the nervous system and induce sleep. However, if these doses are not properly controlled, they may create havoc. They even adversely affect the vital organs of the body. It is advisable to take these sleeping pills under the strict supervision of a doctor.
“Ranitidine is an antacid” With reference to which classification, has this statement been given ?
Ranitidine is labelled as antacid since it is quite effective in neutralising the excess of acidity in the stomach. It is sold in the market under the trade name Zintac.
Why do we require artificial sweetening agents ?
The commonly used sweetening agent i.e., sucrose is a carbohydrate with molecular formula C12H22O11. Since it has high calorific value, it is not recommended to the patients, diabetics in particular which require low calorie diet. Most of the artificial sweeteners are better than sucrose but hardly provide any calories to the body. These are being used as substitutes of sugar.
Write chemical equations for preparing sodium soap from glyceryl oleate and glyceryl palmitate. Structural formulas of these compounds are given :
(i) (C15H31COO)3C3H5 (Glyceryl palmitate)
(ii) (C17H33COO)3 C3H5 (Glyceryl oleate)
Label the hydrophilic and hydrophobic parts in the following molecule which is a detergent. Also identify the functional group(s) present.
Why do we need to classify the drugs in different ways ?
Drugs are to attack different targets which are the biomolecules from which our body is made. Moreover, the drugs also differ in action. Therefore, there is a genuine necessity to classify the drugs in different ways.
Explain the following as used in medicinal chemistry
(a) Lead compounds
(b) Target molecules or drug targets.
(a) Lead compounds are the compounds which are effective in different drugs. They have specific chemical formulas and may be extracted either from natural sources (plants and animals) or may be synthesised in the laboratory.
(b) Target molecules or drug targets. An enzyme (E) functions by combining with the reactant (called substrate) denoted as ‘S’ to form an activated complex known as enzyme-substrate complex (E-S). The complex dissociates to form product and releases the enzyme for carrying out further activity.
Name the macromolecules that are chosen as drug targets.
The different macromolecules or biomolecules which are used as drug targets are carbohydrates, proteins, enzymes, nucleic acids. Out of these, enzymes are the most significant because their deficiency leads to many disorders in the body.
Why the medicines should not be taken without consulting doctors ?
No doubt medicines are panacea for most of the body ailments. But their wrong choice and overdose can cause havoc and may even prove to be fatal. Therefore, it is of utmost importance that the medicines should not be given without consulting doctors.
Define the term chemotherapy. (C.B.S.E. Delhi 2008)
Chemotherapy means the treatment of the disease by means of chemicals that have specific effect upon the disease causing micro-organisms without harming the friendly micro-organisms or bacterias which the body needs.
Which forces are involved in holding the drugs to the active sites of enzymes ?
These are different inter-molecular forces like dipolar forces, hydrogen bonding, van der Waals’ forces etc. The receptor targets have specific roles to perform. They help in transferring message from messengers to the cell. The messengers are in fact chemical compounds which are received by the active sites of the receptor proteins that project out of the surface. In order to accommodate these, the receptors may undergo a change in shape. The receptors are held by the active sites also called binding sites. Once the message is transferred to the cells.
Antacids and antiallergic drugs interfere with the function of histamines but do not interfere with the function of each other. Explain.
They donot interfere with the functioning of each other because they work on different receptors in the body.Histamine stimulates the secretion of pepsin and hydrochloric acid in the stomach. The drug cimetidine (antacid) was designed to prevent the interaction of histamine with the receptors present in the stomach wall. This resulted in release of lesser amount of acid. Antacid and antiallergic drugs work on different receptors.
Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem ? Name two drugs (C.B.S.E. Outside Delhi 2008 Supp.)
Low level of noradrenaline which acts as a neurotransmitter reduces the signal sending ability to the nerves and the patient suffers from depression. Antidepressants are needed to give relief from depression. These are also called tranquilizers or neurologically active drugs. The two specific drugs are iproniazid and phenelzine.
What is meant by the term ‘broad spectrum antibiotic ? Explain.
Broad spectrum antibiotics are the drugs which are effective against a large number of harmful micro-organisms causing diseases.
Chloramphenicol It is a broad spectrum antibiotic, isolated in 1947. It is rapidly absorbed from the gastro intestinal tract and hence can be given orally. It is very effective against typhoid, dysentery, acute fever, certain form of urinary infections, meningitis and pneumonia.
Chioramphenicol is quite easy to synthesise. Therefore, most of the chioramphenicol available in the market is synthetic.
How do antiseptics differ from disinfectants ? Give one example of each.
Many times, the same substance can act as an antiseptic as well as disinfectant by changing the concentration of the solution used. For example, a 0.2 per cent solution of phenol acts as an antiseptic and its 1 percent solution is a disinfectant. Chlorine is used in India for making water fit for drinking at a concentration of 0.2 to 0.4 ppm (parts per million). Low concentration of sulphur dioxide is used for sterilizing squashes for preservation. A few points of distinction between antiseptics and disinfectants are listed.
|1. Can kill or prevent the growth of micro-organisms.||1.Can kill micro-organisms.|
|2. Do not harm the living tissues. Therefore, these can be applied to the skin.||2. Toxic to the living tissues. Therefore, these cannot be applied to the skin.|
|3. These are used for the dressing of wounds, ulcers and in the treatment of diseased skin.||3. These are used for disinfecting floors, toilets, drains, instruments etc.|
Why are cimetidine and ranitidine better antacids than sodium bicarbonate or magnesium or aluminium hydroxides ?
Both sodium bicarbonate and hydroxides of magnesium or aluminium are very good antacids since they neutralise the acidity in the stomach. But their prolong use can cause the secretion of excessive acid in the stomach. This may be quite harmful and may lead to the formation of ulcers. Both cimetidine and ranitidine are better salts without any side effect.
Name a substance which can be used as an antiseptic as well as disinfectant.
About 0.2 per cent solution of phenol can act as antiseptic whereas about 1.0 per cent solution of the same can act as disinfectant.
What are the main constituents of dettol ?
The main constituents of antiseptic dettol are chloroxylenol and terpenol.
What is tincture of iodine ? What is its use ?
Tincture of iodine is a dilute solution of iodine (2 to 3 per cent) prepared in ethanol.
It is a powerful antiseptic particularly in case of fresh wounds.
What are food preservatives ?
Preservation has a major role in the food products. Chemically preserved squashes and crushes can be kept for a fairly long time even after opening the seal of bottle.
A preservative may be defined as the substance which is capable of inhibiting or arresting the process of fermentation, acidification or any other decomposition of food. Salting i.e. addition of table salt is a well known method for food preservation and was applied in ancient times for preserving raw mangoes, tamarind, meat, fish etc. Sugar syrup can also act as a preservative. Vinegar is a useful preservative for pickles. Apart from these, sulphur dioxide and benzoic acid can be employed for the preservation of food. The major source of sulphur dioxide is potassium metabisulphite (K2S2O5). It is fairly stable in neutral and alkaline medium but gets decomposed by weak acids such as carbonic, citric, tartane and malic acids. Benzoic acid is used either as such or in the form of sodium benzoate. However, sulphur dioxide has a better preservative action than sodium benzoate against bacteria and moulds. It also retards the development of yeast in juice but fails to arrest their multiplication once the number has reached a high value. Sorne salts of sorbic acid and propionic acid are also being used these days for the preservation of the food.
The use of preservatives must be properly controlled as their indiscriminate use is likely to be harmful. The preservative should not be injurious to health and should be also non-irritant.
Why is use of aspartame restricted to cold foods and drinks ?
Aspartame is a very good sweetener for foods and drinks. But its use is restricted to cold stuff only. In case these are hot, the sweetener may decompose and it may not be effective any more. It is a very successful and commonly used artificial sweetener. As stated above, it is nearly 100 times as sweet as cane sugar. However, it can be used in soft drinks and cold foods only since it decomposes upon heating. Chemically aspartame is the methyl ester of dipcptide formed by the action of aspartic acid with phenylalanine.
What are artificial sweetening agents ? Give two examples.
Carbohydrates in the form of sugar (sucrose) are the traditional sweeteners and are the essential constituents of our diet. In the present life style, people lack physical activities and exercise and it becomes rather difficult to burn the extra calones that are produced by the carbohydrates. Chemists have provided certain chemicals known as artificial sweeteners which provide the desired sweet taste io the food articles but hardly affect the calorie intake by the body. The most popular among the artificial sweeteners is saccharin which is nearly 550 times more sweet than the cane sugar. It is a boon for the diabetic patients who donot want to take carbohydrates (sugar) which is likely to increase the calories. It is infact, a life saviour for these patients and is in the form of sodium or calcium salt which is water soluble. These days, a number of other sweeteners are also available, e.g.. Aspartame, Alitame, Sucrolose etc.
(a) Aspartame: It is a very successful and commonly used artiticial sweetener. As stated above, it is nearly 100 times as
sweet as cane sugar. However, it can be used in soft drinks and cold foods only since it decomposes upon heating. Chemically
aspartame is the methyl ester of dipeptide formed by the action of aspartic acid with phenylalanine.
(b) Sucrolose: The artificial sweetener as the name suggests is a trichioroderivative of sucrose. It is better, than
aspartame in the sense that it can be used in hot food at the cooking temperature, since it does not decompose on heating.
Moreover, it does not provide calories.
Name the sweetening agent used in the preparation of sweets for a diabetic patient.
Saccharine is the well known sweetening agent which is more than 550 times sweet as compared to sucrose (or sugar). It is commonly used in the preparation of sweets for diabetic patients. Actually, it is not a carbohydrate. Now better sweetening agents are also available.
What problem arises by using alitame as artificial sweetener ?
Alitame is no doubt, a very potent sweetener. Its sweetening capacity is more than 2000 times as compared to ordinary cane sugar or sucrose. But sometimes, it becomes quite difficult to control the sweetness level in the food which is actually desired.
Why are detergents called soapless soaps ?
Detergents are called soapless soaps because they resemble soaps in their cleansing action but they donot contain the usual chemical contents of soaps i.e., sodium or potassium salts of long chain fatty acids. In other words, we can say that they behave as soaps without being actually soaps.
Explain the following terms with suitable examples.
(a) Cationic detergents
(b) Anionic detergents
(c) Neutral detergents.
1. Anionic Detergents: These detergents contain anionic hydrophilic groups. These are generally made from long-chain alcohols which are reacted with concentrated sulphuric acid to form alkyl hydrogen suiphates. These are then neutralised with alkali to give water soluble salts.
A few examples are listed below :
Sodium Alkyl Suiphates: These are the sodium salts of suiphonic acid esters of long chain aliphatic alcohols which normally contain 10 to 15 carbon atoms. The alcohols are formed from fats and oils as a result of hydrogenolysis.
Sodium Alkyl Benzene Suiphonates: A common detergent belonging to this class is Sod – p – dodecyl benzene sulphonate. It is obtained from benzene by reacting with dodecyl chloride in the presence of anhydrous AlCl3 acting as catalyst.
The different steps involved are as follows :
2. Cationic Detergents: In these detergents, the hydrophilic group is of cationic nature. These are generally acetates, chlorides or bromides of quaternary ammonium CH CH CH B salts. The cationic part enclosed in bracket contains long hydrocarbon chain. These detergents have germicidal qualities and are quite expensive as well, The cationic CH3 detergents are present in hair conditioners. Cetyltrimethyl ammonium bromide
3. Non-ionic or neutral Detergent: These detergents are simply long chain organic compounds and are esters in nature. For example, stearic acid and polyethylene glycol react to form a non-ionic detergent.
Non-ionic detergents contain polar groups and form hydrogen bonds with water. Some dishwashing liquids contain non-ionic detergents.
The field of detergents is very vast because of their immense utility. Companies engaged in their manufacture are spending huge amount of money to bring products of better quality.
What are biodegradable and non-biodegradable detergents ? Give an example of each. (C.B.S.E. Delhi 2008, 2009)
Detergents are non-biodegradable in the sense that they cannot be degraded or decomposed by the micro-organisms. They mix with water present in rivers, ponds, lakes etc. as such without getting decomposed and thus cause pollution problems. The biodegradable detergents are the ones which can be degraded. These are being synthesised by reducing the branching of the chain. Sodium n-dodecylbenzene sulphonate is a biodegradable detergent. Even soaps act as biodegradable detergents.
Why do soaps not work in hard water ? (C.B.S.E. Outside Delhi 2009, 2011)
Soaps are water soluble sodium or potassium salts of higher fatty acids like palmitic acid (C15H31COOH), oleic acid (C17H33COOH) and stearic acid (C17H35COOH). Hard water contains certain calcium and magnesium salts which combine with soaps to form corresponding magnesium compounds. These being insoluble, get separated as curdy white precipitates resulting in wastage of soap.
Can you use soaps and synthetic detergents to check the hardness of water ?
Soaps can be used to check hardness of water as they will form insoluble precipitates of calcium and magnesium salts on reacting with hard water. Since detergents do not form any precipitate, they cannot check hardness of water.
Explain the cleansing action of soaps.
In order to understand the cleansing action of soaps let us try to analyse how the clothes become dirty. They first become oily because of the perspiration coming out of the skin and also from the organic matter dispersed in the atmosphere. Dust particles stick to oil drops and the clothes become dirty. In order to wash these, they are dipped in water and soap is applied.
In solution, it dissociates to give carboxylate ions (RCOO–) and the cations (Na+). The alkyl portion which contains a long chain of hydrocarbons is a tail pointing towards the oil drops while the COO portion is the head directed towards water. This is quite evident from the figure where the solid circles (.) represent the polar groups and the wavy lines represent the alkyl portions. This formation is known as micelle and helps in forming a stable emulsion of oil and water by acting as a bridge between the two. The oil droplets along with the particles of the dirt get detached from the fibres of the clothes and pass into the emulsion. In this manner, the clothes become free from dust or dirt. The cleansing action of the soap is depicted in the Fig. 5.15.
If water contains dissolved calcium bicarbonate, out of soaps and synthetic detergents, which one will you use for cleansing clothes ?
Calcium bicarbonate makes water hard. Soap (RCOONa) will react with the salt to form corresponding calcium salt which will be precipitated and wasted. The synthetic detergents are chemically different from soaps. They will not react with the calcium bicarbonate and can be used for cleansing dirty clothes without being precipitated. In other words, there will be no wastage when the detergents are used.
Label the hydrophilic and hydrophobic parts in the following compounds.
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