what is the difference b/w chemical composition of soap and detergent ?state in brief the action of soap in removing an oily spot from a shirt .why are soap not considered suitable for washing when water is hard?
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Soaps are sodium and potassium salts of long chain fatty acids. Detergents are the sodium salts of long chain benzene sulphonic acids or long chain alkyl hydrogen sulphates. So the difference is benzene sulphonic acid group is present in detergents in place of fatty acid group of soaps.
Chemical formula of soap: RCOO-Na+ , where R denotes any long chain alkyl group containing 12 to 18 carbon atoms.
Chemical formula of detergents: R SO3-Na+
Cleansing action of Soap:
Soap is broadly divided in two parts : Hydrophilic head(water loving) and Hydrophobic tail(water repelling). The tail is actually a long chain hydrocarbon part and it has attraction for oil and grease on cloth. When we add soap in dirty cloth with oil spots, the tail part of soap get attached to oily spot and head part orient itself to water this is called micelle. And when we wash the cloth with excess of water this micelle is get removed from cloth and goes in water as shown in figure.
Soap is not suitable for washing clothes with hard water because of the following reasons:
Hard water contains salt of Ca and Mg, when soap is added to hard water, Ca and Mg ions of hard water react with soap forming insoluble Ca and Mg salt of fatty acids which sticks of clothes being washed. Therefore it interfere with the cleansing ability of the soap and makes the cleansing process difficult.
Chemical formula of soap: RCOO-Na+ , where R denotes any long chain alkyl group containing 12 to 18 carbon atoms.
Chemical formula of detergents: R SO3-Na+
Cleansing action of Soap:
Soap is broadly divided in two parts : Hydrophilic head(water loving) and Hydrophobic tail(water repelling). The tail is actually a long chain hydrocarbon part and it has attraction for oil and grease on cloth. When we add soap in dirty cloth with oil spots, the tail part of soap get attached to oily spot and head part orient itself to water this is called micelle. And when we wash the cloth with excess of water this micelle is get removed from cloth and goes in water as shown in figure.
Soap is not suitable for washing clothes with hard water because of the following reasons:
Hard water contains salt of Ca and Mg, when soap is added to hard water, Ca and Mg ions of hard water react with soap forming insoluble Ca and Mg salt of fatty acids which sticks of clothes being washed. Therefore it interfere with the cleansing ability of the soap and makes the cleansing process difficult.
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