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Soap was the first detergentWater dissolves dirt, however oily dirt will not

dissolve in water.

Detergentshelp oil to dissolve in water.Soap was used as the first detergent.

Romans made soap by boiling animal fatwith wood

ash.Now soap is made from oils which smell pleasant

(palm oil) which is boiled with potassium

hydroxide solution.

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Detergent molecules are attracted to both water and oilOil will not dissolvein water.

Oil molecules are hydrophobic water hating.

!etergent molecules are made up of a headand a tail.

"he heads are hydrophilic attracted to water.

"he tails are hydrophobic attracted to oil.

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Detergent molecules are attracted to both waterand oil

"he hydrophobic tails are attracted to oil and bury

themselvesin the oil.

"he hydrophilic heads are attracted to water.

"he detergent molecules pull the oil into a round

droplet which can floatin the water.

"he detergent helps the grease to form an emulsion

a mixtureof tiny droplets of one li#uid in another.

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Many modern detergents are soaplessdetergents

Soaps used to be made of sodium$potassium

hydro%ide and animal$plant oils.

Now most detergents are made using by products of

oil refining.

"hese are called soapless detergents they are betterthan soaps.

Soap forms scum in hard water, which doesn&t

dissolve in water.

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Detergents and pollution"he first soapless detergents caused pollution problems.

'acteria and sewage systems couldnt break them down,

causing foaming in rivers and streams.'iodegradable detergents can now be broen down by

bacteria less liely to cause foaming in rivers.

any detergents contain phosphates a good dirt cleaner.

When they get into rivers, they act as fertilisers, which

encourage the growth of water plants, which use up

the oxygenin the water.