2c soaps, fragrances and skin care Flashcards
(23 cards)
Name the process used to make soaps
Alkaline hydrolysis of fats and oils
List the reactants and products of the two steps in alkaline hydrolysis
Step 1: fat/oil + water -> glycerol + fatty acid
Step 2: fatty acid +NaOH -> soap + water
Describe the structure of a soap
Long, non polar hydrocarbon tail (hydrophobic) and ionic carboxylate head (hydrophilic)
Describe how the structure allows grease to be removed from surfaces
The tail dissolved in the grease and the head is repelled from the grease and dissolves in the surrounding water. This creates ball like structures called micelles which are carried away with the water.
What is the difference between a soap and a detergent?
Detergents are made from the kerosene fraction of crude oil.
Where is it advantageous to use detergents and why?
In hard water areas because the ionic head in the detergent does not react with calcium ions in the hard water so does not cause soap scum to form, unlike soap.
What is an emulsion?
When droplets of a liquid are dispersed in another liquid that does not usually mix with it.
How can emulsions be formed?
Using an emulsifier
How do the structure of emulsifiers make them work?
Emulsifiers are monoglycerides or diglycerides. They have hydrophilic OH groups and hydrophilic hydrocarbon chains so dissolve in both oils and water allowing them to mix.
Give a definition of essential oils
Concentrated extracts from plants of volatile, water-insoluble aromatic compounds
Name the process by which essential oils are extracted
Steam distillation
Give 3 uses of essential oils
Cleaning products, perfumes, cooking
What are terpenes?
Compounds made up of isoprene units that are found in essential oils
Give the systematic name and molecular formula for isoprene
2-methylbuta-1,3-diene (C5H8)
What are oxidised terpenes called?
Terpenoids
What are the effects of exposure to UV radiation on skin?
Premature aging and sun burn
Give the 3 stages of the free radical chain reaction
Initiation, propagation and termination
What is a free radical?
Highly reactive atom with unpaired electrons that is formed when UV breaks molecular bonds
Describe the initiation step
UV breaks a stable molecule into 2 free radicals
Describe the propagation step
Free radicals react with stable compounds to form a different free radical and a different stable compound.
Describe the termination step
Two free radicals collide to form a stable compound
How can free radical damage be mitigated?
By free radical scavengers which react with free radicals to form stable compounds
Give 3 examples of free radical scavengers
Vitamin A, Vitamin C and melatonin
