The soap doesn't work by attaching oil to water, the soap attaches to the water and then the soap is carried away by the water. Oil doesn't dissolve in water, but oil dissolves in soap and soap dissolves in water.

I'm sorry, but that is incorrect. Soap is created as a reaction between fat and an alkaline reagent, often sodium hydroxide. This chemical reaction creates bi-polar molecules, with one side remaining hydrophobic allowing it to bond to other fats, and one side that is hydrophilic and will bond to water.

Oil by itself does not dissolve in soap, it creates a partial emulsification. That partial emulsification will relatively quickly separate back to oil and soap given time, adding water and energy will create a complete emulsion which will hold the water oil and fat together for much longer.

Due to a project at my company, I unfortunately know entirely more about emulsification than I would like.

[–] [email protected] 4 points 2 weeks ago (4 children)

Thank you for the correction on my terminology. Oil doesn't dissolve in soap and soap doesn't dissolve in water, emulsions are not solutions.

However, I think the general point about oil attaching to the soap and the soap attaching to the water still stands. I would still say that "the soap attaches the oil to water" isn't quite right. Per your statement, the soap attaches to both oil and water on opposite sides of the molecule, so the oil isn't really attached to the water - at least not directly. That was the thing I was trying to articulate.

But you also remind me of something a chemistry professor once told me: it's not the soap that cleans, it's not the heat that cleans, it's the physical scrubbing action that cleans. Soap and heat make it much easier, but if you add soap and hot water to a burnt dish and leave it to soak, everything will stay exactly where it is (separated) until you add physical energy to move things.

[–] [email protected] 4 points 2 weeks ago (3 children)

I would still say that "the soap attaches the oil to water" isn't quite right. Per your statement, the soap attaches to both oil and water on opposite sides of the molecule, so the oil isn't really attached to the water - at least not directly. That was the thing I was trying to articulate.

Yeah, it's open to interpretation as we aren't utilizing strict scientific terminology. The reason why i preface it that way is that technically emulsifiers are still oils/fats themselves, they've just undergone a chemical reaction that alters their polarity.

Also, when you are trying to create a proper emulsification the majority of the time you add you emulsifiers to the oils/fats first to create a partial emulsification, and then you add your water and energy to finish it off.

But I understand your reasoning, even the best emulsification is still technically an aided dispersion and will lose its homogenisation over time.

[–] [email protected] 1 points 2 weeks ago (1 children)

And glass is a liquid.

[–] MutilationWave 1 points 2 weeks ago (1 children)

Not below its melting point.

[–] [email protected] 1 points 2 weeks ago

No it is, kind of anyway, there's a whole argument about it. Some argue it's a solid, some argue it's a liquid, some say it's neither but somewhere in between. But, for example, really old glass windows will end up thicker at the bottom. It's basically a highly viscous liquid that takes an extremely long time to flow.

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