EXAM UNIT 2

Can result in molecules gaining sufficient energy for bonds to be broken - responsible for sunburn and contributes to aging of skin

Cause wrinkles by breaking down collagen, creating substances called free radicals that inhibit the natural repair of the skin

Chemical species that contains one unpaired electron and is highly reactive

Have unpaired electrons and are highly reactive

UV light provides energy for the homolytic fission of halogen into reactive halogen atoms or free radicals

Free radicals collide with other species but the number of free radicals is maintained

Free radical are used up by collision with eachother

• Reaction is initiated by UV and once started can continue in the dark • Other substitution products are made such as Ch2Br2, CHBr3, CBr4, together with longer alkanes

Present in many cosmetic products, they contain molecules which can react with free radicals to form stable molecules and prevent chain reaction. E.g. vitamin E

Volatility of the oil so it is carried by the steam. More water can be added from the funnel. Essential oils collect as a mixture of oil and water, but as the two do not mix, they are easily separated.

Unsaturated compounds formed by joining together isoprene units

Terpenes can be oxidised into terpanoids within plants producing some of the compounds responsible for the distinctive aroma of spices

By the alkaline hydrolysis of edible fats and edible oils, fatty acids produced are neutralised by alkali, forming water-soluble ionic salts called soaps

Produces fatty acids and glycerol (3:1)

Water that contains dissolved metal ions like Ca2+ and Mg2+

An insoluble precipitate formed from the reaction between the soap molecule and the ions in the water

Emulsifying reactants - chemicals that can make oil and water become permanently mixed to produce a stable emulsion

Have long non-polar hydrocarbon chain (which is readily soluble in non-polar compounds) and a polar ionic carboxylate head which is water soluble

• Soaps have a long non-polar hydrocarbon chain (which is readily soluble in non-polar compounds) and a polar ionic carboxylate head which is water soluble • During cleaning, the hydrophobic tails dissolve in the droplet of grease, whilst the hydrophobic heads face out into the surrounding water, resulting in ball like structures • Agitation allows soap to break down grease and form suspended droplets, otherwise known as miscelles

Contains small droplets of one liquid dispersed in another liquid

A reaction of edible oils with glycerol

Commonly made by reacting edible oils with glycerol