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Asked by ellen123 to Jess, Christina on 19 Jun 2013.
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Christina Pagel answered on 19 Jun 2013:
ooh that’s quite a complicated question! but here goes…
Imagine that a water particle is like a narrow body with a big head… the particles like to arrange themselves so that all the heads are far apart and all their feet are together…
But this means that there is no room for oil particles to get inside the happy circle of water particles and so they stick together with other oil particles…
The ultimate effect is that oil and water don’t mix. I don’t know if that helps answer your question but it’s quite complicated chemistry (and chemistry is not my strong point anyway!)
But that’s we use detergent to wash dishes – because it stops the water particles sticking together and so oil and water can mix (and we cna wash our dirty plates better!)
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Jess Bean answered on 20 Jun 2013:
As the token chemist here, I think I might be able to explain it a bit clearer.
Water molecules are charged, which means they like to stick to each other – they have a positive and a negative end and so ‘stick’ together just like a magnet (north sticks to south etc..).
With oil particles, the particles have no charge, and so chemicals think of them as long greasy chains that just sit there. When you mix water with oil the water prefers to stay with itself, as they can stick together. With the oil it also likes to stay with itself as because it is charge-less.
Comments
Christina commented on :
thanks Jess – much better explanation than mine! can you tell i gave up chemistry after GCSE? 😀
spacenut1982 commented on :
Also, to make them stick together you would need an emulsifier, which has a hydrophilic head and hydrophobic tail (I may have got that the wrong way round!). And the oil bonds with the hydrophobic end, and the water to the hydrophilic end. Hope this helps!