Chemistry in Every Day Life – Part 3

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Chemistry Notes for Neet, Neet Notes for chemistry, chemistry neet notes, neet notes 2018

COSMETICS

The word cosmetics is derived from Greek word kosmetikos. It means decorating or beautifying or improving complexion of skin. Some of the cosmetics which find use in daily life are discussed below

  1. Creams

Creams are used for facial make-up. These are often classified as:
Clearing creams, cold creams, vanishing creams, sunburn creams and bleach creams.

  • Cleansing creams: Remove facial make up, surface grime, lipstick and oil.
  • Cold creams: Lubricate the skin and prevent roughness and chaffing.
  • Vanishing creams: keep the skin cool and oily.
  • Sun burn creams: Save the skin form sun burn in summer
  • Bleach creams: Exert a bleaching effect on dark skin.
  1. Perfumes

Perfumes are the materials used to provide fragrance. Several requirements have to be fulfilled to make a good perfume and any material, which just gives good smell, may not be a perfume. A perfume invariably consists of three ingredients: a vehicle, fixative and odour producing substance.

  • Vehicle or solvent: The role of the solvent is keep the odour producing substances in solution. Ethanol and water mixture is the most common vehicle used in perfumery.
  • Fixative: The function of the fixative is to equalize the rate of evapouration of various odouriferous components of the perfume by suitably adjusting their volatility. Sandal wood oil finds use as fixative benzoin, glyceryl diacetate and esters of cinnamyl alcohol.

Illustration 8: Name that cyclic ketone which is isolated from the musk of a male
musk deer and used as a perfume?

Solution Muskone

Odoriferous substance

Both natural and synethetic substances are used to impart odour to a perfume. For example: terpenoids like linalool occur in essential oils are natural odour producing compounds while anisaldelhyde (p-methoxy benzal dehyde) is a synthetic odour producing compound.

  1. Talcum power

Talcum power is used to reduce irritation of the skin. Talcum powder like face powders contain talc (Mg3(OH)2Si4O10). Chalk zinc oxide, zinc sterate and suitable perfume act as the other main constituents of talcum power. Often specific ingredients like antiseptic and cooling agents are added. The role of the talk is to act as a powder base and to make skin smooth. Chalk absorbs secretion (perspiration) without showing any evidence of such absorption. Zinc oxide makes enlarged pores and mirror blemishes, whereas zinc makes powder adhere to skin. Baby talcum powder contain considerable amounts of zinc sterate for adhesiveness and boric acid, for antiseptic purposes. Talcum powders need to be dusted with care to prevent inhalation of the fine particles which irritate the lungs.

  1. Deodorants

As the name suggests, deodorants are applied primary to mask the body odour. The body odour result from the bacterial action following perspiration. A deodorant must therefore, possess antibacterial properties. Aluminium salt have been found to possess excellent antibacterial properties. In addition to aluminium salt, ZnO and (C17COO)2Zn also find use in deodorants preparation because they are astringents as well as antiseptics.

Illustration 9: Which chemical substance is added to toilet soaps and cosmetics to
impart the fragrance of rose?

Solution   Geraniol

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