Braingle: 'Immiscible' Brain Teaser

Immiscible

Science brain teasers require understanding of the physical or biological world and the laws that govern it.

Puzzle ID:	#42032
Fun:	(2.75)
Difficulty:	(1.64)
Category:	Science
Submitted By:	tangled_brain
Corrected By:	Winner4600

We all know that oil and water just don't mix.

One thousand years ago, we also knew that everything revolved around the earth, and some people as recently as one hundred years ago knew that the earth was flat!

However, I know that I can get oil and water to mix simply by adding something found in every home.

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Answer

What I add is dishwashing liquid! The reason oil and water don't mix is because oil is nonpolar, while water is polar. The "like dissolves like rule" explains why table salt (NaCl) can be dissolved in water (both are polar), while oil cannot (it's nonpolar).

What's special about the dishwashing liquid is that it is a surfactant, short for SURFace ACTing AgeNT. This gives it the ability to break the surface tension of water. Also, the molecules in the dish soap have one side that is polar and attracted to water and another that is nonpolar and soluble in oil, allowing both the polar water molecules and the nonpolar oil molecules to create a colloid called an emulsion.

There are different kinds of emulsions. Mayonnaise is an emulsion of vinegar and oil, which wouldn't mix if egg yolks weren't added.
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Comments

Radioguy May 24, 2008	Heh heh, I knew the answer, and I'm first to comment! Great teaser, and good explanation.
safire2191 May 24, 2008	nice teaser! I use an agent called tween at work. i think that may be the active ingredient. i could be wrong though
tpg76 May 24, 2008	Good teaser. But - a fairly contorted problem statement! (Flat earth??) I guess it comes with having your screen name!
dogzrok May 24, 2008	Very nice. I knew the answer when I saw it. Very.....long explanation....Great teaser.
kunju May 25, 2008	love it
rt1819 May 28, 2008	What about a blender?? Fun teaser.
tangled_brain May 28, 2008	hehe you could use a blender, but the oil would just clump back together once you turned it off. try it!
yangjun Jun 05, 2008	this is very easy to answer but it is still fun as i LOVE science!!!!(especially chemistry)
drat Jun 09, 2008	yup soap is a simple emulsifier, but there are other things in the kitchen that do the same . love chemistry
unklemyke Aug 19, 2008	And here I thought it was those scrubbing bubbles that did all the work. That'll teach me not to trust commercials. Nice teaser.
Paladin Apr 09, 2009	Fun and interesting.