Chemistry in Everyday Life
Topic – Drugs and Medicines
Drugs are chemical substances of low molecular mass which interact with molecular targets and produce biological responses. When the biological response is therapeutic and useful, these chemicals are called medicines. Thus medicines are used in diagnosis, prevention and cure of diseases.
Drugs can be classified into different groups on different basis. On the basis of pharmacological effect drugs can be classified as Analgesics, Antipyretics, Antiseptics, and Antidepressants. Drugs can also be classified on the basis of their action, on the basis of their chemical structure and on the basis of molecular targets.
Drugs are designed to interact with specific targets so as to minimize the side effects and to localize the action of the drug.
Different types of drugs are used for the treatment of different types of diseases. These are antipyretics (used to lower the temperature of the body), analgesics (used to relieve pains), non-narcotic drugs (non addictive analgesics) , narcotic drugs (habit forming analgesics), tranquillizers(used for mental diseases), antiseptics (used to either kill or prevent the growth of microorganisms), disinfectants (used to kill microorganisms but they cannot be applied on living tissues), antimalarials (used to treat malaria), antimicrobial (used to cure infection caused by microorganisms), antifertility drugs (used to control the pregnancy), antacids (used to neutralize excess acid in the gastric juices), antihistamines (used to diminish the main actions of histamine released in the body), anaesthetics (used to produce general or local insensibility to pains and other sensations).
Topic – Chemicals in Food
The chemicals which are added to food to improve its shelf-life, taste, odour and appearance are called food additives.
Food preservatives are the chemical substances that are added to the food materials to prevent their spoilage and to retain their nutritive value for long periods. They check the growth of micro-organisms in food. The most common preservative is sodium benzoate.
Artificial sweetening agents are the chemical substances, which give sweetening effect to the food and enhance its odour and flavour.
Some most commonly used artificial sweetening agents are saccharin (life saver for people suffering from diabetes), aspartame (used as a sugar substitute in cold drinks and cold food), alitame and sucrose.
Antioxidants are the compounds which retard the action of oxygen on food thus reducing its speed of decomposition by oxidation. They help in the preservation of food. They are more reactive towards oxygen as compared to the material they are protecting.
Topic – Soaps and Detergents
Soaps and synthetic detergents are the substances, which are used as cleansing agents. Soap is the sodium (or potassium) salt of a long chain fatty acid which has cleansing properties in water.
The alkaline hydrolysis of the fats and oils yields glycerol and soap. This reaction is known as saponification.
There are many types of soaps such as Toilet soaps, medicated soaps, transparent soaps and soap chips.
Soaps and detergents consist of two parts: hydrophobic part (which dissolves in oil, dirt or grease) and hydrophilic part (which dissolves in water).
Soaps cannot be used in hard water as they form a curd white precipitate with calcium and magnesium ions present in the hard water.
Synthetic detergents are cleansing agents, which have all the properties of soaps, but actually do not contain any soap. These can be used both in soft and hard water as they give foam even in hard water.
Depending upon the nature of the surface of the active groups, synthetic detergents are classified into anionic detergents (sodium salt of sulphonated long chain alcohols or hydrocarbons), cationic detergents (quaternary ammonium salt of amines with acetates, chlorides or bromides as anions) and non-ionic detergents (formed when stearic acid reacts with polyethylene glycol).
Cationic detergents are more expensive than anionic detergents. They possess germicidal properties.
Liquid dishwashing detergents are of non-ionic type. Mechanism of cleansing action of this type of detergents is same as that of soaps. These also remove grease and oil by micelle formation.
Detergents with straight chain of hydrocarbons are preferred over branched chain as the latter are non-biodegradable and cause environmental pollution.