soap (1 Viewer)

[jmcloon]

can someone please in simple terms tell me how soap works and the difference to detergent with chemical matter please

 

[nesstar]

Soap is made up of a metal cation (usually sodium) and a sufactant anion. The cation has nothing to do with the cleaning process. When in water, the ions dissociate. The surfactant anion has a long hydrocarbon tail which is hydrophobic (water hating) and a polar anionic end which is hydrophilic (water loving). The hydrophobic end forms dispersion forces with oily substances while the hydrophilic end forms hydrogen bonds with water, hence soap acts as a bridge between dirt/oil and water.

Theres a table on HSC online that compares detergents and soaps:
www.hsc.csu.edu.au/chemistry/options/industrial

hope that helps!

 

[utopia_parkway]

but what is the different between a soap and a anionic detergent

 

[nesstar]

In terms of structure, anionic detergents usually contain a benzene ring and either a sulfate or sulfanoate ion. Anionic detergents are therefore more effective in hard water than soap, as sulfates/sulfanoates don't ppt out with Ca and Mg ions like surfactant anions in soap do. There are also differences regarding environmental issues: soap is biodegradable while detergent is not; detergent often contains phosphate 'builders' which cause algal blooms.
What else did u want to know?

 

[jmcloon]

thanks nesstar that is a bit better now that the soap the polar end it attaches to the dirt and the nonpolar attches to the water and is pulls the dirt off the surface is that right

 

[nesstar]

other way!
For soap:
the polar end is the ionic end, which is negatively charged and hydrophilic - attaches to water
the non-polar end (made of hydrocarbons) is hdrophobic - attaches to dirt
Hope that clarifies it!!

 

[mervvyn]

It's not always negatively charged though, you can have cationic (with a +ve head) or non ionic (with some Os at one end to make it slightly negative) detergents with their own uses. The reason i say that is because it was in the NEAP trial, where you had to distinguish them and their uses/properties so it might be worth knowing the differences.

 

[utopia_parkway]

but soaps are always negativly charged

 

[nesstar]

It's not always negatively charged though, you can have cationic (with a +ve head) or non ionic (with some Os at one end to make it slightly negative) detergents with their own uses. The reason i say that is because it was in the NEAP trial, where you had to distinguish them and their uses/properties so it might be worth knowing the differences.

there are different types of detergents, but not soaps

someone asked the difference between anionic detergent and soap, that's why i didn't mention the others...

Soap will dissociate in water; the cation won't do a thing and the sufactant anion does the cleaning

 

[mervvyn]

can someone please in simple terms tell me how soap works and the difference to detergent with chemical matter please

I thought they were asking about detergents in general, doesn't matter...