By Two Lab Coats
Apr 01, 2019

How Does Soap Work?

Nexus Health

@twolabcoats

How does soap work? Well, here at twolabcoats we’re all about saving the planet and if we can help you save some water by shaving some time of your daily ‘pondering random thoughts in shower time’, we’re happy to help.
 
We’re almost 100% sure at some time in your life you’ve done the oil and water experiment. This experiment consists of pouring some oil followed by some water into a glass. The oil floats in a separate layer above the water. When we add soap to this mixture these layers disappear and we are left with one liquid. To fully understand why this happens, we first have to understand some terms - hydrophobic, hydrophilic, polar and non-polar.
 
Hydrophobic means water-hating and hydrophilic means water-loving. Molecules can either be completely one or the other, or made up of both hydrophilic and hydrophobic parts. With polar and non-polar we are, for the sake of this article, only concerned with one rule - like likes like. This means that polar molecules like polar molecules, and vice versa with non-polar molecules.
 
Water is polar and oil is non-polar. As like likes like, when the water and oil are in the glass together, they don’t like it. To summarise, they’re actually pretty full of themselves and only want their own company; hence, we see the two layers. We can think of the oil like our skin, which is naturally oily to protect us from the environment and, I’m sure no explanation is needed here, the water is like the water coming out of the shower head.
 
We shower because our skin gets dirty, but just standing under water doesn’t necessarily work because the polar water does not mix with the non-polar oil on our skin, and hence we aren’t actually getting clean. This is where soap comes in. Soap molecules have both a hydrophobic and a hydrophilic end so one end hates water and the other doesn’t. The hydrophobic ends of the soap molecule attach to the oil in our skin that gets dirty, while the hydrophilic end attaches to the water coming from the showerhead, allowing us to successfully lift the dirt and wash it down the drain. And just like that, you’re a clean bean again.

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