Chemistry in Everyday Life

16.21 

At elevated temperatures, aspartame is unstable and break down to give a tasteless compound because of which aspartame is limited to cold foods and drinks.

Aspartame is methyl ester of the dipeptide obtained from phenylalanine and aspartic acid. It is about 180 times as sweet as cane sugar. The structure of aspartame is as follows:

16.20 

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 acids are some common examples of food preservatives.

16.19

Iodine is a powerful antiseptic. It is employed as tincture of iodine which is an alcohol-water solution containing 2-3 percent of iodine. Iodine is widely used in healing and treatment of wounds as it kills all the microbes present in the wounded region.

16.18

Dettol is a well known antiseptic. It is a mixture or combination of chloroxylenol and terpineol in a suitable solvent.

The structure of chloroxylenol is as follows:

The structure of terpineol is as follows:

16.17

Phenol is one such particular substance that can act both as an antiseptic as well as a disinfectant depending upon the concentration of the solution used. An antiseptic is used to prevent the growth of germs in cuts and wounds.

For instance, a phenol of 0.2% concentration acts as antiseptic and phenol of concentration 1% acts as a disinfectant.

16.16 

Magnesium or Aluminium hydroxides do not tackle with the root cause of acidity that is they reduce the acidity by reacting with excess acid present in the stomach [neutralization reaction].

On the other hand cimetidine and ranitidine relieve acidity by preventing interaction of histamine with receptors of stomach walls and hence release of excess acid by stomach walls is stopped. So the root cause of acidity is totally eliminated.

Therefore cimetidine and ranitidine relieve the acidity by tackling the root cause whereas magnesium or aluminum hydroxide just relieves by healing only the mere cause of acidity.

16.15 

Antiseptics and disinfectants are effective against micro-organisms. Antiseptics are applied to the living tissues such as wounds, cuts, ulcers, and diseased skin surfaces, while disinfectants are applied only 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.

16.14 

Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad spectrum antibiotics. Chloramphenicol is an example of a broad spectrum antibiotic. It has the following structure: -

It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, meningitis, and certain forms of urinary infections. Two other examples of broad spectrum antibiotics are vancomycin and ofloxacin. Ampicillin and amoxicillin? synthetically modified from penicillin are also broad spectrum antibiotics.

16.13 

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

16.12

Specific drugs affect only some specific or 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.